RNA recognition motif;

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                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 2020930303  211 VLYLKNLSPRVTERDLVSLFARFqekkGPPIQFRMM----TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVI 283
Cdd:smart00360   1 TLFVGNLPPDTTEEELRELFSKF----GKVESVRLVrdkeTGKSKGFAFVEFESEEDAEKALEALNGKELDGRPLKV 73

RNA recognition motif (RRM) domain [Translation, ribosomal structure and biogenesis];

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2020930303 210 MVLYLKNLSPRVTERDLVSLFARFqekkGPPIQFRMM----TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:COG0724     2 MKIYVGNLPYSVTEEDLRELFSEY----GEVTSVKLItdreTGRSRGFGFVEMPDDEEAQAAIEALNGAELMGRTLKVNE 77

                  ....*...
gi 2020930303 286 GKNKKQRS 293
Cdd:COG0724    78 ARPREERP 85

RNA recognition motif;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 2020930303  211 VLYLKNLSPRVTERDLVSLFARFqekkGPPIQFRMM----TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVI 283
Cdd:smart00360   1 TLFVGNLPPDTTEEELRELFSKF----GKVESVRLVrdkeTGKSKGFAFVEFESEEDAEKALEALNGKELDGRPLKV 73

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFqekkGPPIQFRMM---TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKIL 281
Cdd:pfam00076   1 LFVGNLPPDTTEEDLKDLFSKF----GPIKSIRLVrdeTGRSKGFAFVEFEDEEDAEKAIEALNGKELGGREL 69

RNA recognition motif 1 (RRM1) found in the U1A/U2B"/SNF protein family; This subfamily corresponds to the RRM1 of U1A/U2B"/SNF protein family which contains Drosophila sex determination protein SNF and its two mammalian counterparts, U1 small nuclear ribonucleoprotein A (U1 snRNP A or U1-A or U1A) and U2 small nuclear ribonucleoprotein B" (U2 snRNP B" or U2B"), all of which consist of two RNA recognition motifs (RRMs), connected by a variable, flexible linker. SNF is an RNA-binding protein found in the U1 and U2 snRNPs of Drosophila where it is essential in sex determination and possesses a novel dual RNA binding specificity. SNF binds with high affinity to both Drosophila U1 snRNA stem-loop II (SLII) and U2 snRNA stem-loop IV (SLIV). It can also bind to poly(U) RNA tracts flanking the alternatively spliced Sex-lethal (Sxl) exon, as does Drosophila Sex-lethal protein (SXL). U1A is an RNA-binding protein associated with the U1 snRNP, a small RNA-protein complex involved in pre-mRNA splicing. U1A binds with high affinity and specificity to stem-loop II (SLII) of U1 snRNA. It is predominantly a nuclear protein that shuttles between the nucleus and the cytoplasm independently of interactions with U1 snRNA. Moreover, U1A may be involved in RNA 3'-end processing, specifically cleavage, splicing and polyadenylation, through interacting with a large number of non-snRNP proteins. U2B", initially identified to bind to stem-loop IV (SLIV) at the 3' end of U2 snRNA, is a unique protein that comprises of the U2 snRNP. Additional research indicates U2B" binds to U1 snRNA stem-loop II (SLII) as well and shows no preference for SLIV or SLII on the basis of binding affinity. Moreover, U2B" does not require an auxiliary protein for binding to RNA, and its nuclear transport is independent of U2 snRNA binding.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 2020930303 212 LYLKNLSPRVTERDL-VSLFARFQeKKGPPIQFRMM-TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEFGK 287
Cdd:cd12246     2 LYINNLNEKIKKDELkRSLYALFS-QFGPVLDIVASkSLKMRGQAFVVFKDVESATNALRALQGFPFYGKPMRIQYAK 78

RNA recognition motif (RRM) found in eukaryotic translation initiation factor 3 subunit G (eIF-3G) and similar proteins; This subfamily corresponds to the RRM of eIF-3G and similar proteins. eIF-3G, also termed eIF-3 subunit 4, or eIF-3-delta, or eIF3-p42, or eIF3-p44, is the RNA-binding subunit of eIF3, a large multisubunit complex that plays a central role in the initiation of translation by binding to the 40 S ribosomal subunit and promoting the binding of methionyl-tRNAi and mRNA. eIF-3G binds 18 S rRNA and beta-globin mRNA, and therefore appears to be a nonspecific RNA-binding protein. eIF-3G is one of the cytosolic targets and interacts with mature apoptosis-inducing factor (AIF). eIF-3G contains one RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). This family also includes yeast eIF3-p33, a homolog of vertebrate eIF-3G, plays an important role in the initiation phase of protein synthesis in yeast. It binds both, mRNA and rRNA, fragments due to an RRM near its C-terminus.

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gi 2020930303 216 NLSPRVTERDLVSLFARFQekkgpPIQfRMM------TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:cd12408     6 NLSEDATEEDLRELFRPFG-----PIS-RVYlakdkeTGQSKGFAFVTFETREDAERAIEKLNGFGYDNLILSVEW 75

RNA recognition motif 1 (RRM1) found in the VICKZ family proteins; Thid subfamily corresponds to the RRM1 of IGF2BPs (or IMPs) found in the VICKZ family that have been implicated in the post-transcriptional regulation of several different RNAs and in subcytoplasmic localization of mRNAs during embryogenesis. IGF2BPs are composed of two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and four hnRNP K homology (KH) domains.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFarfQEKKGPPIQFRMMTGrmrGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEFGKNKK 290
Cdd:cd12358     1 LYIGNLSSDVNESDLRQLF---EEHKIPVSSVLVKKG---GYAFVDCPDQSWADKAIEKLNGKILQGKVIEVEHSVPKK 73

RNA recognition motif 1 (RRM1) found in vertebrate insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2); This subgroup corresponds to the RRM1 of IGF2BP2 (IGF2 mRNA-binding protein 2 or IMP-2), also termed hepatocellular carcinoma autoantigen p62, or VICKZ family member 2, which is a ubiquitously expressed RNA-binding protein involved in the stimulation of insulin action. It is predominantly nuclear. SNPs in IGF2BP2 gene are implicated in susceptibility to type 2 diabetes. IGF2BP2 plays an important role in cellular motility; it regulates the expression of PINCH-2, an important mediator of cell adhesion and motility, and MURF-3, a microtubule-stabilizing protein, through direct binding to their mRNAs. IGF2BP2 may be involved in the regulation of mRNA stability through the interaction with the AU-rich element-binding factor AUF1. IGF2BP2 binds initially to nascent beta-actin transcripts and facilitates the subsequent binding of the shuttling IGF2BP1. IGF2BP2 contains four hnRNP K-homology (KH) domains, two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a RGG RNA-binding domain.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFArfqEKKGPpiqfrmMTGRM---RGQAFITFPNKEIAWQALHLVNG-YKLHGKILVIEFGK 287
Cdd:cd12626     4 LYIGNLSPAVTAEDLRQLFG---DRKLP------LTGQVllkSGYAFVDYPDQNWAIRAIETLSGkVELHGKVMEVDYSV 74

                  ...
gi 2020930303 288 NKK 290
Cdd:cd12626    75 PKK 77

RNA recognition motif (RRM) found in cleavage stimulation factor subunit 2 (CSTF2), yeast ortholog mRNA 3'-end-processing protein RNA15 and similar proteins; This subfamily corresponds to the RRM domain of CSTF2, its tau variant and eukaryotic homologs. CSTF2, also termed cleavage stimulation factor 64 kDa subunit (CstF64), is the vertebrate conterpart of yeast mRNA 3'-end-processing protein RNA15. It is expressed in all somatic tissues and is one of three cleavage stimulatory factor (CstF) subunits required for polyadenylation. CstF64 contains an N-terminal RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), a CstF77-binding domain, a repeated MEARA helical region and a conserved C-terminal domain reported to bind the transcription factor PC-4. During polyadenylation, CstF interacts with the pre-mRNA through the RRM of CstF64 at U- or GU-rich sequences within 10 to 30 nucleotides downstream of the cleavage site. CSTF2T, also termed tauCstF64, is a paralog of the X-linked cleavage stimulation factor CstF64 protein that supports polyadenylation in most somatic cells. It is expressed during meiosis and subsequent haploid differentiation in a more limited set of tissues and cell types, largely in meiotic and postmeiotic male germ cells, and to a lesser extent in brain. The loss of CSTF2T will cause male infertility, as it is necessary for spermatogenesis and fertilization. Moreover, CSTF2T is required for expression of genes involved in morphological differentiation of spermatids, as well as for genes having products that function during interaction of motile spermatozoa with eggs. It promotes germ cell-specific patterns of polyadenylation by using its RRM to bind to different sequence elements downstream of polyadenylation sites than does CstF64. The family also includes yeast ortholog mRNA 3'-end-processing protein RNA15 and similar proteins. RNA15 is a core subunit of cleavage factor IA (CFIA), an essential transcriptional 3'-end processing factor from Saccharomyces cerevisiae. RNA recognition by CFIA is mediated by an N-terminal RRM, which is contained in the RNA15 subunit of the complex. The RRM of RNA15 has a strong preference for GU-rich RNAs, mediated by a binding pocket that is entirely conserved in both yeast and vertebrate RNA15 orthologs.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 2020930303 211 VLYLKNLSPRVTERDLVSLFarfqEKKGPPIQFRMM----TGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:cd12398     2 SVFVGNIPYDATEEQLKEIF----SEVGPVVSFRLVtdreTGKPKGYGFCEFRDAETALSAVRNLNGYELNGRPLRVDF 76

RNA recognition motif 3 (RRM3) found in the Hu proteins family; This subfamily corresponds to the RRM3 of the Hu proteins family which represent a group of RNA-binding proteins involved in diverse biological processes. Since the Hu proteins share high homology with the Drosophila embryonic lethal abnormal vision (ELAV) protein, the Hu family is sometimes referred to as the ELAV family. Drosophila ELAV is exclusively expressed in neurons and is required for the correct differentiation and survival of neurons in flies. The neuronal members of the Hu family include Hu-antigen B (HuB or ELAV-2 or Hel-N1), Hu-antigen C (HuC or ELAV-3 or PLE21), and Hu-antigen D (HuD or ELAV-4), which play important roles in neuronal differentiation, plasticity and memory. HuB is also expressed in gonads. Hu-antigen R (HuR or ELAV-1 or HuA) is the ubiquitously expressed Hu family member. It has a variety of biological functions mostly related to the regulation of cellular response to DNA damage and other types of stress. Hu proteins perform their cytoplasmic and nuclear molecular functions by coordinately regulating functionally related mRNAs. In the cytoplasm, Hu proteins recognize and bind to AU-rich RNA elements (AREs) in the 3' untranslated regions (UTRs) of certain target mRNAs, such as GAP-43, vascular epithelial growth factor (VEGF), the glucose transporter GLUT1, eotaxin and c-fos, and stabilize those ARE-containing mRNAs. They also bind and regulate the translation of some target mRNAs, such as neurofilament M, GLUT1, and p27. In the nucleus, Hu proteins function as regulators of polyadenylation and alternative splicing. Each Hu protein contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an ARE. RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:cd12377     2 IFVYNLAPDADESLLWQLFGPFGAVQNVKIIRDFTTNKCKGYGFVTMTNYDEAAVAIASLNGYRLGGRVLQVSF 75

RNA recognition motif (RRM) found in serine/arginine-rich splicing factor SRSF10, SRSF12 and similar proteins; This subfamily corresponds to the RRM of SRSF10 and SRSF12. SRSF10, also termed 40 kDa SR-repressor protein (SRrp40), or FUS-interacting serine-arginine-rich protein 1 (FUSIP1), or splicing factor SRp38, or splicing factor, arginine/serine-rich 13A (SFRS13A), or TLS-associated protein with Ser-Arg repeats (TASR). It is a serine-arginine (SR) protein that acts as a potent and general splicing repressor when dephosphorylated. It mediates global inhibition of splicing both in M phase of the cell cycle and in response to heat shock. SRSF10 emerges as a modulator of cholesterol homeostasis through the regulation of low-density lipoprotein receptor (LDLR) splicing efficiency. It also regulates cardiac-specific alternative splicing of triadin pre-mRNA and is required for proper Ca2+ handling during embryonic heart development. In contrast, the phosphorylated SRSF10 functions as a sequence-specific splicing activator in the presence of a nuclear cofactor. It activates distal alternative 5' splice site of adenovirus E1A pre-mRNA in vivo. Moreover, SRSF10 strengthens pre-mRNA recognition by U1 and U2 snRNPs. SRSF10 localizes to the nuclear speckles and can shuttle between nucleus and cytoplasm. SRSF12, also termed 35 kDa SR repressor protein (SRrp35), or splicing factor, arginine/serine-rich 13B (SFRS13B), or splicing factor, arginine/serine-rich 19 (SFRS19), is a serine/arginine (SR) protein-like alternative splicing regulator that antagonizes authentic SR proteins in the modulation of alternative 5' splice site choice. For instance, it activates distal alternative 5' splice site of the adenovirus E1A pre-mRNA in vivo. Both, SRSF10 and SRSF12, contain a single N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), followed by a C-terminal RS domain rich in serine-arginine dipeptides.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFqekkGP------PIQFRmmTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:cd12312     3 LFVRNVADDTRPDDLRREFGRY----GPivdvyiPLDFY--TRRPRGFAYIQFEDVRDAEDALYYLDRTRFLGREIEIQF 76

RNA recognition motif 2 (RRM2) found in vertebrate RNA-binding protein RBM23, RBM39 and similar proteins; This subfamily corresponds to the RRM2 of RBM39 (also termed HCC1), a nuclear autoantigen that contains an N-terminal arginine/serine rich (RS) motif and three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). An octapeptide sequence called the RS-ERK motif is repeated six times in the RS region of RBM39. Although the cellular function of RBM23 remains unclear, it shows high sequence homology to RBM39 and contains two RRMs. It may possibly function as a pre-mRNA splicing factor.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGK 279
Cdd:cd12284     1 LYVGSLHFNITEDMLRGIFEPFGKIEFVQLQKDPETGRSKGYGFIQFRDAEDAKKALEQLNGFELAGR 68

RNA recognition motif 2 (RRM2) found in RNA-binding protein 28 (RBM28) and similar proteins; This subfamily corresponds to the RRM2 of RBM28 and Nop4p. RBM28 is a specific nucleolar component of the spliceosomal small nuclear ribonucleoproteins (snRNPs), possibly coordinating their transition through the nucleolus. It specifically associates with U1, U2, U4, U5, and U6 small nuclear RNAs (snRNAs), and may play a role in the maturation of both small nuclear and ribosomal RNAs. RBM28 has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an extremely acidic region between RRM2 and RRM3. The family also includes nucleolar protein 4 (Nop4p or Nop77p) encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p also contains four RRMs.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARF---QEKKGPpiqfRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHG 278
Cdd:cd12414     2 LIVRNLPFKCTEDDLKKLFSKFgkvLEVTIP----KKPDGKLRGFAFVQFTNVADAAKAIKGMNGKKIKG 67

RNA recognition motif 1 (RRM1) found in RNA-binding protein 40 (RBM40) and similar proteins; This subfamily corresponds to the RRM1 of RBM40, also known as RNA-binding region-containing protein 3 (RNPC3) or U11/U12 small nuclear ribonucleoprotein 65 kDa protein (U11/U12-65K protein), It serves as a bridging factor between the U11 and U12 snRNPs. It contains two repeats of RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), connected by a linker that includes a proline-rich region. It binds to the U11-associated 59K protein via its RRM1 and employs the RRM2 to bind hairpin III of the U12 small nuclear RNA (snRNA). The proline-rich region might be involved in protein-protein interactions.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRmmtGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:cd12238     2 LLVRHLPPELSEDDKEDLLKHFGATSVRVMKRR---GKLKHTAFATFDNEQAASKALSRLHQLKILGKRLVVEY 72

heterogeneous nuclear ribonucleoprotein R, Q family; Sequences in this subfamily include the human heterogeneous nuclear ribonucleoproteins (hnRNP) R, Q, and APOBEC-1 complementation factor (aka APOBEC-1 stimulating protein). These proteins contain three RNA recognition domains (rrm: pfam00076) and a somewhat variable C-terminal domain.

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gi 2020930303 219 PR-VTERDLVSLFarfqEKKGPPIQFRMM---TGRMRGQAFITFPNKEIAWQALHLVNGYKLH-GKIL 281
Cdd:TIGR01648  67 PRdLYEDELVPLF----EKAGPIYELRLMmdfSGQNRGYAFVTFCGKEEAKEAVKLLNNYEIRpGRLL 130

RNA recognition motif (RRM) found in pre-mRNA branch site protein p14 (SF3B14) and similar proteins; This subfamily corresponds to the RRM of SF3B14 (also termed p14), a 14 kDa protein subunit of SF3B which is a multiprotein complex that is an integral part of the U2 small nuclear ribonucleoprotein (snRNP) and the U11/U12 di-snRNP. SF3B is essential for the accurate excision of introns from pre-messenger RNA and has been involved in the recognition of the pre-mRNA's branch site within the major and minor spliceosomes. SF3B14 associates directly with another SF3B subunit called SF3B155. It is also present in both U2- and U12-dependent spliceosomes and may contribute to branch site positioning in both the major and minor spliceosome. Moreover, SF3B14 interacts directly with the pre-mRNA branch adenosine early in spliceosome assembly and within the fully assembled spliceosome. SF3B14 contains one well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

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gi 2020930303 211 VLYLKNLSPRVTERDLVSLFARFqekkGPPIQFRM-MTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVI 283
Cdd:cd12241     4 ILYVRNLPYKISSEELYDLFGKY----GAIRQIRIgNTKETRGTAFVVYEDIFDAKNACDHLSGFNVCNRYLVV 73

RNA recognition motif 2 (RRM2) found in nucleolysin TIA-1 isoform p40 (p40-TIA-1) and similar proteins; This subgroup corresponds to the RRM2 of p40-TIA-1, the 40-kDa isoform of T-cell-restricted intracellular antigen-1 (TIA-1), and a cytotoxic granule-associated RNA-binding protein mainly found in the granules of cytotoxic lymphocytes. TIA-1 can be phosphorylated by a serine/threonine kinase that is activated during Fas-mediated apoptosis, and function as the granule component responsible for inducing apoptosis in cytolytic lymphocyte (CTL) targets. It is composed of three N-terminal highly homologous RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a glutamine-rich C-terminal auxiliary domain containing a lysosome-targeting motif. TIA-1 interacts with RNAs containing short stretches of uridylates and its RRM2 can mediate the specific binding to uridylate-rich RNAs.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 2020930303 209 HMVLYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGK 279
Cdd:cd12618     2 HFHVFVGDLSPEITTEDIKAAFAPFGRISDARVVKDMATGKSKGYGFVSFFNKWDAENAIQQMGGQWLGGR 72

RNA recognition motif (RRM) found in RNA-binding protein 7 (RBM7) and similar proteins; This subfamily corresponds to the RRM of RBM7, RBM11 and their eukaryotic homologous. RBM7 is an ubiquitously expressed pre-mRNA splicing factor that enhances messenger RNA (mRNA) splicing in a cell-specific manner or in a certain developmental process, such as spermatogenesis. It interacts with splicing factors SAP145 (the spliceosomal splicing factor 3b subunit 2) and SRp20, and may play a more specific role in meiosis entry and progression. Together with additional testis-specific RNA-binding proteins, RBM7 may regulate the splicing of specific pre-mRNA species that are important in the meiotic cell cycle. RBM11 is a novel tissue-specific splicing regulator that is selectively expressed in brain, cerebellum and testis, and to a lower extent in kidney. It is localized in the nucleoplasm and enriched in SRSF2-containing splicing speckles. It may play a role in the modulation of alternative splicing during neuron and germ cell differentiation. Both, RBM7 and RBM11, contain an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a region lacking known homology at the C-terminus. The RRM is responsible for RNA binding, whereas the C-terminal region permits nuclear localization and homodimerization.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFArfqeKKGPPIQFRMMT---GRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIE 284
Cdd:cd12336     4 LFVGNLDPRVTEEILYELFL----QAGPLEGVKIPKdpnGKPKNFAFVTFKHEVSVPYAIQLLNGIRLFGREIRIK 75

RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein R (hnRNP R) and similar proteins; This subfamily corresponds to the RRM1 in hnRNP R, hnRNP Q, APOBEC-1 complementation factor (ACF), and dead end protein homolog 1 (DND1). hnRNP R is a ubiquitously expressed nuclear RNA-binding protein that specifically binds mRNAs with a preference for poly(U) stretches. It has been implicated in mRNA processing and mRNA transport, and also acts as a regulator to modify binding to ribosomes and RNA translation. hnRNP Q is also a ubiquitously expressed nuclear RNA-binding protein. It has been identified as a component of the spliceosome complex, as well as a component of the apobec-1 editosome, and has been implicated in the regulation of specific mRNA transport. ACF is an RNA-binding subunit of a core complex that interacts with apoB mRNA to facilitate C to U RNA editing. It may also act as an apoB mRNA recognition factor and chaperone, and play a key role in cell growth and differentiation. DND1 is essential for maintaining viable germ cells in vertebrates. It interacts with the 3'-untranslated region (3'-UTR) of multiple messenger RNAs (mRNAs) and prevents micro-RNA (miRNA) mediated repression of mRNA. This family also includes two functionally unknown RNA-binding proteins, RBM46 and RBM47. All members in this family, except for DND1, contain three conserved RNA recognition motifs (RRMs); DND1 harbors only two RRMs.

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gi 2020930303 212 LYLKNLsPR-VTERDLVSLFarfqEKKGPPIQFRMM---TGRMRGQAFITFPNKEIAWQALHLVNGYKL 276
Cdd:cd12249     4 VFVGKI-PRdVFEDELVPLF----EKCGKIYELRLMmdfSGLNRGYAFVTYTNKEAAQRAVKTLNNYEI 67

RNA recognition motif 3 (RRM3) found in vertebrate Hu-antigen D (HuD); This subgroup corresponds to the RRM3 of HuD, also termed ELAV-like protein 4 (ELAV-4), or paraneoplastic encephalomyelitis antigen HuD, one of the neuronal members of the Hu family. The neuronal Hu proteins play important roles in neuronal differentiation, plasticity and memory. HuD has been implicated in various aspects of neuronal function, such as the commitment and differentiation of neuronal precursors as well as synaptic remodeling in mature neurons. HuD also functions as an important regulator of mRNA expression in neurons by interacting with AU-rich RNA element (ARE) and stabilizing multiple transcripts. Moreover, HuD regulates the nuclear processing/stability of N-myc pre-mRNA in neuroblastoma cells. And it also regulates the neurite elongation and morphological differentiation. HuD specifically bound poly(A) RNA. Like other Hu proteins, HuD contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an ARE. RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEFGKNKKQ 291
Cdd:cd12656     6 IFVYNLSPDSDESVLWQLFGPFGAVNNVKVIRDFNTNKCKGFGFVTMTNYDEAAMAIASLNGYRLGDRVLQVSFKTNKTH 85

                  .
gi 2020930303 292 R 292
Cdd:cd12656    86 K 86

RNA recognition motif (RRM) found in vertebrate RNA-binding protein 7 (RBM7); This subfamily corresponds to the RRM of RBM7, a ubiquitously expressed pre-mRNA splicing factor that enhances messenger RNA (mRNA) splicing in a cell-specific manner or in a certain developmental process, such as spermatogenesis. RBM7 interacts with splicing factors SAP145 (the spliceosomal splicing factor 3b subunit 2) and SRp20. It may play a more specific role in meiosis entry and progression. Together with additional testis-specific RNA-binding proteins, RBM7 may regulate the splicing of specific pre-mRNA species that are important in the meiotic cell cycle. RBM7 contains an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a region lacking known homology at the C-terminus.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFArfqeKKGPPIQFRM---MTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIE 284
Cdd:cd12592     4 LFVGNLDTKVTEELLFELFL----QAGPVIKVKIpkdKDGKPKQFAFVNFKHEVSVPYAMNLLNGIKLYGRPLKIQ 75

RNA recognition motif 1 (RRM1) found in Arabidopsis thaliana phragmoplastin interacting protein 1 (PHIP1) and similar proteins; This subfamily corresponds to the RRM1 of PHIP1. A. thaliana PHIP1 and its homologs represent a novel class of plant-specific RNA-binding proteins that may play a unique role in the polarized mRNA transport to the vicinity of the cell plate. The family members consist of multiple functional domains, including a lysine-rich domain (KRD domain) that contains three nuclear localization motifs (KKKR/NK), two RNA recognition motifs (RRMs), and three CCHC-type zinc fingers. PHIP1 is a peripheral membrane protein and is localized at the cell plate during cytokinesis in plants. In addition to phragmoplastin, PHIP1 interacts with two Arabidopsis small GTP-binding proteins, Rop1 and Ran2. However, PHIP1 interacted only with the GTP-bound form of Rop1 but not the GDP-bound form. It also binds specifically to Ran2 mRNA.

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gi 2020930303 222 TERDLVSLFARFqekkGPPIQFRMMT----GRMRGQAFITFPNKEIAWQALHLvNGYKLHGKILVIE 284
Cdd:cd12271    11 TEAEIRSYFSSC----GEVRSVDLMRfpdsGNFRGIAFITFKTEEAAKRALAL-DGEMLGNRFLKVE 72

RNA recognition motif 2 (RRM2) found in nucleolysin TIAR and similar proteins; This subgroup corresponds to the RRM2 of nucleolysin TIAR, also termed TIA-1-related protein, a cytotoxic granule-associated RNA-binding protein that shows high sequence similarity with 40-kDa isoform of T-cell-restricted intracellular antigen-1 (p40-TIA-1). TIAR is mainly localized in the nucleus of hematopoietic and nonhematopoietic cells. It is translocated from the nucleus to the cytoplasm in response to exogenous triggers of apoptosis. TIAR possesses nucleolytic activity against cytolytic lymphocyte (CTL) target cells. It can trigger DNA fragmentation in permeabilized thymocytes, and thus may function as an effector responsible for inducing apoptosis. TIAR is composed of three N-terminal, highly homologous RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a glutamine-rich C-terminal auxiliary domain containing a lysosome-targeting motif. It interacts with RNAs containing short stretches of uridylates and its RRM2 can mediate the specific binding to uridylate-rich RNAs.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 2020930303 209 HMVLYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGK 279
Cdd:cd12617     1 HFHVFVGDLSPEITTEDIKSAFAPFGKISDARVVKDMATGKSKGYGFVSFYNKLDAENAIVHMGGQWLGGR 71

RNA recognition motif (RRM) found in Transformer-2 protein homolog beta (TRA-2 beta) and similar proteins; This subgroup corresponds to the RRM of TRA2-beta or TRA-2-beta, also termed splicing factor, arginine/serine-rich 10 (SFRS10), or transformer-2 protein homolog B, a mammalian homolog of Drosophila transformer-2 (Tra2). TRA2-beta is a serine/arginine-rich (SR) protein that controls the pre-mRNA alternative splicing of the calcitonin/calcitonin gene-related peptide (CGRP), the survival motor neuron 1 (SMN1) protein and the tau protein. It contains a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), flanked by the N- and C-terminal arginine/serine (RS)-rich regions. TRA2-beta specifically binds to two types of RNA sequences, the CAA and (GAA)2 sequences, through the RRMs in different RNA binding modes.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 2020930303 217 LSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEFGKNK 289
Cdd:cd12641    15 LSLYTTERDLREVFSKYGPIADVSIVYDQQSRRSRGFAFVYFENVDDAKEAKERANGMELDGRRIRVDFSITK 87

RNA recognition motif (RRM) found in the FET family of RNA-binding proteins; This subfamily corresponds to the RRM of FET (previously TET) (FUS/TLS, EWS, TAF15) family of RNA-binding proteins. This ubiquitously expressed family of similarly structured proteins predominantly localizing to the nuclear, includes FUS (also known as TLS or Pigpen or hnRNP P2), EWS (also known as EWSR1), TAF15 (also known as hTAFII68 or TAF2N or RPB56), and Drosophila Cabeza (also known as SARFH). The corresponding coding genes of these proteins are involved in deleterious genomic rearrangements with transcription factor genes in a variety of human sarcomas and acute leukemias. All FET proteins interact with each other and are therefore likely to be part of the very same protein complexes, which suggests a general bridging role for FET proteins coupling RNA transcription, processing, transport, and DNA repair. The FET proteins contain multiple copies of a degenerate hexapeptide repeat motif at the N-terminus. The C-terminal region consists of a conserved nuclear import and retention signal (C-NLS), a putative zinc-finger domain, and a conserved RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), which is flanked by 3 arginine-glycine-glycine (RGG) boxes. FUS and EWS might have similar sequence specificity; both bind preferentially to GGUG-containing RNAs. FUS has also been shown to bind strongly to human telomeric RNA and to small low-copy-number RNAs tethered to the promoter of cyclin D1. To date, nothing is known about the RNA binding specificity of TAF15.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2020930303 212 LYLKNLSPRVTERDLVSLF------ARFQEKKGPPIQFRM--MTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVI 283
Cdd:cd12280     1 IFVSGLPPDVTIDELADLFgqigiiKRYKDTWPPKIKIYTdkETGKPKGEATLTYEDPSAAKAAIEWFNGKEFRGNKIKV 80

                  ..
gi 2020930303 284 EF 285
Cdd:cd12280    81 SL 82

RNA recognition motif 1 (RRM1) found in plant polypyrimidine tract-binding protein homolog 1 and 2 (PTBPH1 and PTBPH2); This subfamily corresponds to the RRM1 of PTBPH1 and PTBPH2. Although their biological roles remain unclear, PTBPH1 and PTBPH2 show significant sequence similarity to polypyrimidine tract binding protein (PTB) that is an important negative regulator of alternative splicing in mammalian cells and also functions at several other aspects of mRNA metabolism, including mRNA localization, stabilization, polyadenylation, and translation. Both, PTBPH1 and PTBPH2, contain three RNA recognition motifs (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

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gi 2020930303 211 VLYLKNLSPRVTERDLVSLFARFqekkGPPIQFRMMTGRMRGQAFITFPNKEiawQALHLVNGY 274
Cdd:cd12686     4 VLHLRNLPWECTEEELIELCKPF----GTVVNTKCNVGANKNQAFVEFADLN---QAISMVSYY 60

RNA recognition motif 3 (RRM3) found in vertebrate nucleolin; This subfamily corresponds to the RRM3 of ubiquitously expressed protein nucleolin, also termed protein C23, is a multifunctional major nucleolar phosphoprotein that has been implicated in various metabolic processes, such as ribosome biogenesis, cytokinesis, nucleogenesis, cell proliferation and growth, cytoplasmic-nucleolar transport of ribosomal components, transcriptional repression, replication, signal transduction, inducing chromatin decondensation, etc. Nucleolin exhibits intrinsic self-cleaving, DNA helicase, RNA helicase and DNA-dependent ATPase activities. It can be phosphorylated by many protein kinases, such as the major mitotic kinase Cdc2, casein kinase 2 (CK2), and protein kinase C-zeta. Nucleolin shares similar domain architecture with gar2 from Schizosaccharomyces pombe and NSR1 from Saccharomyces cerevisiae. The highly phosphorylated N-terminal domain of nucleolin is made up of highly acidic regions separated from each other by basic sequences, and contains multiple phosphorylation sites. The central domain of nucleolin contains four closely adjacent N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), which suggests that nucleolin is potentially able to interact with multiple RNA targets. The C-terminal RGG (or GAR) domain of nucleolin is rich in glycine, arginine and phenylalanine residues, and contains high levels of NG,NG-dimethylarginines.

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gi 2020930303 211 VLYLKNLSPRVTERDLVSLFarfqeKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEF 285
Cdd:cd12405     3 TLVVNNLSYSATEESLQSVF-----EKATSIRIPQNNGRPKGYAFVEFESVEDAKEALESCNNTEIEGRSIRLEF 72

RNA recognition motif 1 (RRM1) found in vertebrate insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1); This subgroup corresponds to the RRM1 of IGF2BP1 (IGF2 mRNA-binding protein 1 or IMP-1), also termed coding region determinant-binding protein (CRD-BP), or VICKZ family member 1, or zipcode-binding protein 1 (ZBP-1). IGF2BP1 is a multi-functional regulator of RNA metabolism that has been implicated in the control of aspects of localization, stability, and translation for many mRNAs. It is predominantly located in cytoplasm and was initially identified as a trans-acting factor that interacts with the zipcode in the 3'- untranslated region (UTR) of the beta-actin mRNA, which is important for its localization and translational regulation. It inhibits IGF-II mRNA translation through binding to the 5'-UTR of the transcript. IGF2BP1 also acts as human immunodeficiency virus type 1 (HIV-1) Gag-binding factor that interacts with HIV-1 Gag protein and blocks the formation of infectious HIV-1 particles. IGF2BP1 promotes mRNA stabilization; it functions as a coding region determinant (CRD)-binding protein that binds to the coding region of betaTrCP1 mRNA and prevents miR-183-mediated degradation of betaTrCP1 mRNA. It also promotes c-myc mRNA stability by associating with the CRD and stabilizes CD44 mRNA via interaction with the 3'-UTR of the transcript. In addition, IGF2BP1 specifically interacts with both Hepatitis C virus (HCV) 5'-UTR and 3'-UTR, further recruiting eIF3 and enhancing HCV internal ribosome entry site (IRES)-mediated translation initiation via the 3'-UTR. IGF2BP1 contains four hnRNP K-homology (KH) domains, two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a RGG RNA-binding domain. It also contains two putative nuclear export signals (NESs) and a putative nuclear localization signal (NLS).

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFArfQEKKGPPIQFRMMTgrmrGQAFITFPNKEIAWQALHLVNG-YKLHGKILVIEFGKNKK 290
Cdd:cd12625     4 LYIGNLNESVTPADLEKVFE--DHKISYSGQFLVKS----GYAFVDCPDEQWAMKAIETFSGkVELHGKRLEIEHSVPKK 77

RNA recognition motif (RRM) found in the scaffold attachment factor (SAFB) family; This subfamily corresponds to the RRM domain of the SAFB family, including scaffold attachment factor B1 (SAFB1), scaffold attachment factor B2 (SAFB2), SAFB-like transcriptional modulator (SLTM), and similar proteins, which are ubiquitously expressed. SAFB1, SAFB2 and SLTM have been implicated in many diverse cellular processes including cell growth and transformation, stress response, and apoptosis. They share high sequence similarities and all contain a scaffold attachment factor-box (SAF-box, also known as SAP domain) DNA-binding motif, an RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a region rich in glutamine and arginine residues. SAFB1 is a nuclear protein with a distribution similar to that of SLTM, but unlike that of SAFB2, which is also found in the cytoplasm. To a large extent, SAFB1 and SLTM might share similar functions, such as the inhibition of an oestrogen reporter gene. The additional cytoplasmic localization of SAFB2 implies that it could play additional roles in the cytoplasmic compartment which are distinct from the nuclear functions shared with SAFB1 and SLTM.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIE 284
Cdd:cd12417     2 LWISGLSDTTKAADLKKIFSKYGKVVSAKVVTSARTPGSRCYGYVTMASVEEADLCIKSLNKTELHGRVITVE 74

RNA recognition motif 2 (RRM2) found in granule-associated RNA binding proteins (p40-TIA-1 and TIAR), and yeast nuclear and cytoplasmic polyadenylated RNA-binding protein PUB1; This subfamily corresponds to the RRM3 of TIA-1, TIAR, and PUB1. Nucleolysin TIA-1 isoform p40 (p40-TIA-1 or TIA-1) and nucleolysin TIA-1-related protein (TIAR) are granule-associated RNA binding proteins involved in inducing apoptosis in cytotoxic lymphocyte (CTL) target cells. They share high sequence similarity and are expressed in a wide variety of cell types. TIA-1 can be phosphorylated by a serine/threonine kinase that is activated during Fas-mediated apoptosis.TIAR is mainly localized in the nucleus of hematopoietic and nonhematopoietic cells. It is translocated from the nucleus to the cytoplasm in response to exogenous triggers of apoptosis. Both TIA-1 and TIAR bind specifically to poly(A) but not to poly(C) homopolymers. They are composed of three N-terminal highly homologous RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a glutamine-rich C-terminal auxiliary domain containing a lysosome-targeting motif. TIA-1 and TIAR interact with RNAs containing short stretches of uridylates and their RRM2 can mediate the specific binding to uridylate-rich RNAs. The C-terminal auxiliary domain may be responsible for interacting with other proteins. In addition, TIA-1 and TIAR share a potential serine protease-cleavage site (Phe-Val-Arg) localized at the junction between their RNA binding domains and their C-terminal auxiliary domains. This subfamily also includes a yeast nuclear and cytoplasmic polyadenylated RNA-binding protein PUB1, termed ARS consensus-binding protein ACBP-60, or poly uridylate-binding protein, or poly(U)-binding protein, which has been identified as both a heterogeneous nuclear RNA-binding protein (hnRNP) and a cytoplasmic mRNA-binding protein (mRNP). It may be stably bound to a translationally inactive subpopulation of mRNAs within the cytoplasm. PUB1 is distributed in both, the nucleus and the cytoplasm, and binds to poly(A)+ RNA (mRNA or pre-mRNA). Although it is one of the major cellular proteins cross-linked by UV light to polyadenylated RNAs in vivo, PUB1 is nonessential for cell growth in yeast. PUB1 also binds to T-rich single stranded DNA (ssDNA); however, there is no strong evidence implicating PUB1 in the mechanism of DNA replication. PUB1 contains three RRMs, and a GAR motif (glycine and arginine rich stretch) that is located between RRM2 and RRM3.

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gi 2020930303 213 YLKNLSPRVTERDLVSLFARFqekkGPPIQFRMMtgRMRGQAFITFPNKEIAWQALHLVNGYKLHGKIL 281
Cdd:cd12354     4 YVGNITKGLTEALLQQTFSPF----GQILEVRVF--PDKGYAFIRFDSHEAATHAIVSVNGTIINGQAV 66

RNA recognition motif (RRM) found in cyclophilin-33 (Cyp33) and similar proteins; This subfamily corresponds to the RRM of Cyp33, also termed peptidyl-prolyl cis-trans isomerase E (PPIase E), or cyclophilin E, or rotamase E. Cyp33 is a nuclear RNA-binding cyclophilin with an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal PPIase domain. Cyp33 possesses RNA-binding activity and preferentially binds to polyribonucleotide polyA and polyU, but hardly to polyG and polyC. It binds specifically to mRNA, which can stimulate its PPIase activity. Moreover, Cyp33 interacts with the third plant homeodomain (PHD3) zinc finger cassette of the mixed lineage leukemia (MLL) proto-oncoprotein and a poly-A RNA sequence through its RRM domain. It further mediates downregulation of the expression of MLL target genes HOXC8, HOXA9, CDKN1B, and C-MYC, in a proline isomerase-dependent manner. Cyp33 also possesses a PPIase activity that catalyzes cis-trans isomerization of the peptide bond preceding a proline, which has been implicated in the stimulation of folding and conformational changes in folded and unfolded proteins. The PPIase activity can be inhibited by the immunosuppressive drug cyclosporin A.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKIL 281
Cdd:cd12347     1 LYVGGLAEEVDEKVLHAAFIPFGDIVDIQIPLDYETEKHRGFAFVEFEEAEDAAAAIDNMNESELFGRTI 70

RNA recognition motif 4 (RRM4) found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM4 of type I poly(A)-binding proteins (PABPs), highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in theThe CD corresponds to the RRM. regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. The family represents type I polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 1 (PABP-1 or PABPC1), polyadenylate-binding protein 3 (PABP-3 or PABPC3), polyadenylate-binding protein 4 (PABP-4 or APP-1 or iPABP), polyadenylate-binding protein 5 (PABP-5 or PABPC5), polyadenylate-binding protein 1-like (PABP-1-like or PABPC1L), polyadenylate-binding protein 1-like 2 (PABPC1L2 or RBM32), polyadenylate-binding protein 4-like (PABP-4-like or PABPC4L), yeast polyadenylate-binding protein, cytoplasmic and nuclear (PABP or ACBP-67), and similar proteins. PABP-1 is an ubiquitously expressed multifunctional protein that may play a role in 3' end formation of mRNA, translation initiation, mRNA stabilization, protection of poly(A) from nuclease activity, mRNA deadenylation, inhibition of mRNA decapping, and mRNP maturation. Although PABP-1 is thought to be a cytoplasmic protein, it is also found in the nucleus. PABP-1 may be involved in nucleocytoplasmic trafficking and utilization of mRNP particles. PABP-1 contains four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), a less well conserved linker region, and a proline-rich C-terminal conserved domain (CTD). PABP-3 is a testis-specific poly(A)-binding protein specifically expressed in round spermatids. It is mainly found in mammalian and may play an important role in the testis-specific regulation of mRNA homeostasis. PABP-3 shows significant sequence similarity to PABP-1. However, it binds to poly(A) with a lower affinity than PABP-1. Moreover, PABP-1 possesses an A-rich sequence in its 5'-UTR and allows binding of PABP and blockage of translation of its own mRNA. In contrast, PABP-3 lacks the A-rich sequence in its 5'-UTR. PABP-4 is an inducible poly(A)-binding protein (iPABP) that is primarily localized to the cytoplasm. It shows significant sequence similarity to PABP-1 as well. The RNA binding properties of PABP-1 and PABP-4 appear to be identical. PABP-5 is encoded by PABPC5 gene within the X-specific subinterval, and expressed in fetal brain and in a range of adult tissues in mammalian, such as ovary and testis. It may play an important role in germ cell development. Moreover, unlike other PABPs, PABP-5 contains only four RRMs, but lacks both the linker region and the CTD. PABP-1-like and PABP-1-like 2 are the orthologs of PABP-1. PABP-4-like is the ortholog of PABP-5. Their cellular functions remain unclear. The family also includes the yeast PABP, a conserved poly(A) binding protein containing poly(A) tails that can be attached to the 3'-ends of mRNAs. The yeast PABP and its homologs may play important roles in the initiation of translation and in mRNA decay. Like vertebrate PABP-1, the yeast PABP contains four RRMs, a linker region, and a proline-rich CTD as well. The first two RRMs are mainly responsible for specific binding to poly(A). The proline-rich region may be involved in protein-protein interactions.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFqekkGPPIQFRMMT---GRMRGQAFITFPNKEIAWQALHLVNGYKLHGKIL 281
Cdd:cd12381     4 LYVKNLDDTIDDEKLREEFSPF----GTITSAKVMTdegGRSKGFGFVCFSSPEEATKAVTEMNGRIIGGKPL 72

RNA recognition motif 1 (RRM1) found in vertebrate RNA-binding protein 39 (RBM39) and similar proteins; This subfamily corresponds to the RRM1 of RNA-binding protein 39 (RBM39), RNA-binding protein 23 (RBM23) and similar proteins. RBM39 (also termed HCC1) is a nuclear autoantigen that contains an N-terminal arginine/serine rich (RS) motif and three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). An octapeptide sequence called the RS-ERK motif is repeated six times in the RS region of RBM39. Although the cellular function of RBM23 remains unclear, it shows high sequence homology to RBM39 and contains two RRMs. It may possibly function as a pre-mRNA splicing factor.

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gi 2020930303 216 NLSPRVTERDLVSLFarfqEKKGPPIQFRMM----TGRMRGQAFITFPNKEIAWQALHLvNGYKLHGKILVI 283
Cdd:cd12283     6 QLSLKARERDLYEFF----SKAGKVRDVRLImdrnSRRSKGVAYVEFYDVESVPLALAL-TGQRLLGQPIMV 72

RNA recognition motif 3 (RRM3) found in vertebrate Hu-antigen R (HuR); This subgroup corresponds to the RRM3 of HuR, also termed ELAV-like protein 1 (ELAV-1), the ubiquitously expressed Hu family member. It has a variety of biological functions mostly related to the regulation of cellular response to DNA damage and other types of stress. HuR has an anti-apoptotic function during early cell stress response. It binds to mRNAs and enhances the expression of several anti-apoptotic proteins, such as p21waf1, p53, and prothymosin alpha. HuR also has pro-apoptotic function by promoting apoptosis when cell death is unavoidable. Furthermore, HuR may be important in muscle differentiation, adipogenesis, suppression of inflammatory response and modulation of gene expression in response to chronic ethanol exposure and amino acid starvation. Like other Hu proteins, HuR contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an AU-rich RNA element (ARE). RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

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gi 2020930303 212 LYLKNLSPRVTERDLVSLFARFQEKKGPPIQFRMMTGRMRGQAFITFPNKEIAWQALHLVNGYKLHGKILVIEFGKNKKQ 291
Cdd:cd12653     5 IFIYNLGQDADEGILWQMFGPFGAVTNVKVIRDFNTNKCKGFGFVTMTNYEEAAMAIASLNGYRLGDKILQVSFKTNKSH 84

                  .
gi 2020930303 292 R 292
Cdd:cd12653    85 K 85