RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1720367449   1 MINLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSF 48
Cdd:cd12535    39 MINLYTDKETGKLKGEATVSFDDPPSAKAAIDWFDGKEFSGNPIKVSF 86

RNA recognition motif (RRM) found in vertebrate fused in Ewing's sarcoma protein (FUS), TATA-binding protein-associated factor 15 (TAF15) and similar proteins; This subgroup corresponds to the RRM of FUS and TAF15. FUS (TLS or Pigpen or hnRNP P2), also termed 75 kDa DNA-pairing protein (POMp75), or oncoprotein TLS (Translocated in liposarcoma), is a member of the FET (previously TET) (FUS/TLS, EWS, TAF15) family of RNA- and DNA-binding proteins whose expression is altered in cancer. It is a multi-functional protein and has been implicated in pre-mRNA splicing, chromosome stability, cell spreading, and transcription. FUS was originally identified in human myxoid and round cell liposarcomas as an oncogenic fusion with the stress-induced DNA-binding transcription factor CHOP (CCAAT enhancer-binding homologous protein) and later as hnRNP P2, a component of hnRNP H complex assembled on pre-mRNA. It can form ternary complexes with hnRNP A1 and hnRNP C1/C2. Additional research indicates that FUS binds preferentially to GGUG-containing RNAs. In the presence of Mg2+, it can bind both single- and double-stranded DNA (ssDNA/dsDNA) and promote ATP-independent annealing of complementary ssDNA and D-loop formation in superhelical dsDNA. FUS has been shown to be recruited by single stranded noncoding RNAs to the regulatory regions of target genes such as cyclin D1, where it represses transcription by disrupting complex formation. TAF15 (TAFII68), also termed TATA-binding protein-associated factor 2N (TAF2N), or RNA-binding protein 56 (RBP56), originally identified as a TAF in the general transcription initiation TFIID complex, is a novel RNA/ssDNA-binding protein with homology to the proto-oncoproteins FUS and EWS (also termed EWSR1), belonging to the FET family as well. TAF15 likely functions in RNA polymerase II (RNAP II) transcription by interacting with TFIID and subunits of RNAP II itself. TAF15 is also associated with U1 snRNA, chromatin and RNA, in a complex distinct from the Sm-containing U1 snRNP that functions in splicing. Like other members in the FET family, both FUS and TAF15 contain an N-terminal Ser, Gly, Gln and Tyr-rich region composed of multiple copies of a degenerate hexapeptide repeat motif. The C-terminal region consists of a conserved nuclear import and retention signal (C-NLS), a C2/C2 zinc-finger motif, a conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and at least 1 arginine-glycine-glycine (RGG)-repeat region.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1720367449   1 MINLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSF 48
Cdd:cd12535    39 MINLYTDKETGKLKGEATVSFDDPPSAKAAIDWFDGKEFSGNPIKVSF 86

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

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1720367449   6 TDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFATRRPE 54
Cdd:COG0724    35 TDRETGRSRGFGFVEMPDDEEAQAAIEALNGAELMGRTLKVNEARPREE 83

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.

                          10        20        30
                  ....*....|....*....|....*....|....*...
gi 1720367449   8 KDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIK 45
Cdd:pfam00076  33 DETGRSKGFAFVEFEDEEDAEKAIEALNGKELGGRELK 70

Zinc finger domain; Zinc finger domain in Ran-binding proteins (RanBPs), and other proteins. In RanBPs, this domain binds RanGDP.

                           10        20
                   ....*....|....*....|....*..
gi 1720367449   87 GDWVCPnpSCGNMNFARRNSCNQCNEP 113
Cdd:smart00547   1 GDWECP--ACTFLNFASRSKCFACGAP 25

RNA recognition motif (RRM) found in vertebrate fused in Ewing's sarcoma protein (FUS), TATA-binding protein-associated factor 15 (TAF15) and similar proteins; This subgroup corresponds to the RRM of FUS and TAF15. FUS (TLS or Pigpen or hnRNP P2), also termed 75 kDa DNA-pairing protein (POMp75), or oncoprotein TLS (Translocated in liposarcoma), is a member of the FET (previously TET) (FUS/TLS, EWS, TAF15) family of RNA- and DNA-binding proteins whose expression is altered in cancer. It is a multi-functional protein and has been implicated in pre-mRNA splicing, chromosome stability, cell spreading, and transcription. FUS was originally identified in human myxoid and round cell liposarcomas as an oncogenic fusion with the stress-induced DNA-binding transcription factor CHOP (CCAAT enhancer-binding homologous protein) and later as hnRNP P2, a component of hnRNP H complex assembled on pre-mRNA. It can form ternary complexes with hnRNP A1 and hnRNP C1/C2. Additional research indicates that FUS binds preferentially to GGUG-containing RNAs. In the presence of Mg2+, it can bind both single- and double-stranded DNA (ssDNA/dsDNA) and promote ATP-independent annealing of complementary ssDNA and D-loop formation in superhelical dsDNA. FUS has been shown to be recruited by single stranded noncoding RNAs to the regulatory regions of target genes such as cyclin D1, where it represses transcription by disrupting complex formation. TAF15 (TAFII68), also termed TATA-binding protein-associated factor 2N (TAF2N), or RNA-binding protein 56 (RBP56), originally identified as a TAF in the general transcription initiation TFIID complex, is a novel RNA/ssDNA-binding protein with homology to the proto-oncoproteins FUS and EWS (also termed EWSR1), belonging to the FET family as well. TAF15 likely functions in RNA polymerase II (RNAP II) transcription by interacting with TFIID and subunits of RNAP II itself. TAF15 is also associated with U1 snRNA, chromatin and RNA, in a complex distinct from the Sm-containing U1 snRNP that functions in splicing. Like other members in the FET family, both FUS and TAF15 contain an N-terminal Ser, Gly, Gln and Tyr-rich region composed of multiple copies of a degenerate hexapeptide repeat motif. The C-terminal region consists of a conserved nuclear import and retention signal (C-NLS), a C2/C2 zinc-finger motif, a conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and at least 1 arginine-glycine-glycine (RGG)-repeat region.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1720367449   1 MINLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSF 48
Cdd:cd12535    39 MINLYTDKETGKLKGEATVSFDDPPSAKAAIDWFDGKEFSGNPIKVSF 86

RNA recognition motif (RRM) found in vertebrate Ewing Sarcoma Protein (EWS); This subgroup corresponds to the RRM of EWS, also termed Ewing sarcoma breakpoint region 1 protein, a member of the FET (previously TET) (FUS/TLS, EWS, TAF15) family of RNA- and DNA-binding proteins whose expression is altered in cancer. It is a multifunctional protein and may play roles in transcription and RNA processing. EWS is involved in transcriptional regulation by interacting with the preinitiation complex TFIID and the RNA polymerase II (RNAPII) complexes. It is also associated with splicing factors, such as the U1 snRNP protein U1C, suggesting its implication in pre-mRNA splicing. Additionally, EWS has been shown to regulate DNA damage-induced alternative splicing (AS). Like other members in the FET family, EWS contains an N-terminal Ser, Gly, Gln and Tyr-rich region composed of multiple copies of a degenerate hexapeptide repeat motif. The C-terminal region consists of a conserved nuclear import and retention signal (C-NLS), a C2/C2 zinc-finger motif, a conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and at least 1 arginine-glycine-glycine (RGG)-repeat region. EWS specifically binds to poly G and poly U RNA. It also binds to the proximal-element DNA of the macrophage-specific promoter of the CSF-1 receptor gene.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 1720367449   1 MINLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVS 47
Cdd:cd12533    37 MINIYTDKETGKPKGDATVSYEDPPAAKAAVEWFDGKDFQGNKLKVS 83

RNA recognition motif;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*
gi 1720367449    2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKV 46
Cdd:smart00360  29 VRLVRDKETGKSKGFAFVEFESEEDAEKALEALNGKELDGRPLKV 73

RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1720367449   2 INLYTDKDtGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVS 47
Cdd:cd00590    28 VRIVRDRD-GKSKGFAFVEFESPEDAEKALEALNGTELGGRPLKVS 72

RNA recognition motif (RRM) found in heterogeneous nuclear ribonucleoprotein G (hnRNP G), Y chromosome RNA recognition motif 1 (hRBMY), testis-specific heterogeneous nuclear ribonucleoprotein G-T (hnRNP G-T) and similar proteins; This subfamily corresponds to the RRM domain of hnRNP G, also termed glycoprotein p43 or RBMX, an RNA-binding motif protein located on the X chromosome. It is expressed ubiquitously and has been implicated in the splicing control of several pre-mRNAs. Moreover, hnRNP G may function as a regulator of transcription for SREBP-1c and GnRH1. Research has shown that hnRNP G may also act as a tumor-suppressor since it upregulates the Txnip gene and promotes the fidelity of DNA end-joining activity. In addition, hnRNP G appears to play a critical role in proper neural development of zebrafish and frog embryos. The family also includes several paralogs of hnRNP G, such as hRBMY and hnRNP G-T (also termed RNA-binding motif protein, X-linked-like-2). Both, hRBMY and hnRNP G-T, are exclusively expressed in testis and critical for male fertility. Like hnRNP G, hRBMY and hnRNP G-T interact with factors implicated in the regulation of pre-mRNA splicing, such as hTra2-beta1 and T-STAR. Although members in this family share a high conserved N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), they appear to recognize different RNA targets. For instance, hRBMY interacts specifically with a stem-loop structure in which the loop is formed by the sequence CA/UCAA. In contrast, hnRNP G associates with single stranded RNA sequences containing a CCA/C motif. In addition to the RRM, hnRNP G contains a nascent transcripts targeting domain (NTD) in the middle region and a novel auxiliary RNA-binding domain (RBD) in its C-terminal region. The C-terminal RBD exhibits distinct RNA binding specificity, and would play a critical role in the regulation of alternative splicing by hnRNP G.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1720367449   4 LYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFATR 51
Cdd:cd12382    33 LMKDRETNKSRGFAFVTFESPADAKDAARDMNGKELDGKAIKVEQATK 80

RNA recognition motif (RRM) found in Helicobacter pylori HP0827 protein and similar proteins; This subfamily corresponds to the RRM of H. pylori HP0827, a putative ssDNA-binding protein 12rnp2 precursor, containing one RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). The ssDNA binding may be important in activation of HP0827.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1720367449   7 DKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd12399    33 DRETKRPRGFGFVELQEEESAEKAIAKLDGTDFMGRTIRVNEA 75

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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd12347    28 IQIPLDYETEKHRGFAFVEFEEAEDAAAAIDNMNESELFGRTIRVNLA 75

RNA recognition motif (RRM) found in ist3 family; This subfamily corresponds to the RRM of the ist3 family that includes fungal U2 small nuclear ribonucleoprotein (snRNP) component increased sodium tolerance protein 3 (ist3), X-linked 2 RNA-binding motif proteins (RBMX2) found in Metazoa and plants, and similar proteins. Gene IST3 encoding ist3, also termed U2 snRNP protein SNU17 (Snu17p), is a novel yeast Saccharomyces cerevisiae protein required for the first catalytic step of splicing and for progression of spliceosome assembly. It binds specifically to the U2 snRNP and is an intrinsic component of prespliceosomes and spliceosomes. Yeast ist3 contains an atypical RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). In the yeast pre-mRNA retention and splicing complex, the atypical RRM of ist3 functions as a scaffold that organizes the other two constituents, Bud13p (bud site selection 13) and Pml1p (pre-mRNA leakage 1). Fission yeast Schizosaccharomyces pombe gene cwf29 encoding ist3, also termed cell cycle control protein cwf29, is an RNA-binding protein complexed with cdc5 protein 29. It also contains one RRM. The biological function of RBMX2 remains unclear. It shows high sequence similarity to yeast ist3 protein and harbors one RRM as well.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKV 46
Cdd:cd12411    39 INLVRDKKTGKSKGFAFLAYEDQRSTILAVDNLNGIKLLGRTIRV 83

RNA recognition motif 2 (RRM2) found in yeast protein gar2 and similar proteins; This subfamily corresponds to the RRM2 of yeast protein gar2, a novel nucleolar protein required for 18S rRNA and 40S ribosomal subunit accumulation. It shares similar domain architecture with nucleolin from vertebrates and NSR1 from Saccharomyces cerevisiae. The highly phosphorylated N-terminal domain of gar2 is made up of highly acidic regions separated from each other by basic sequences, and contains multiple phosphorylation sites. The central domain of gar2 contains two closely adjacent N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The C-terminal RGG (or GAR) domain of gar2 is rich in glycine, arginine and phenylalanine residues.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVS 47
Cdd:cd12448    28 VRLPTDRETGQPKGFGYVDFSTIDSAEAAIDALGGEYIDGRPIRLD 73

RNA recognition motif 2 (RRM2) found in Nicotiana sylvestris chloroplastic 33 kDa ribonucleoprotein (NsCP33) and similar proteins; The family includes NsCP33, Arabidopsis thaliana chloroplastic 31 kDa ribonucleoprotein (CP31A) and mitochondrial glycine-rich RNA-binding protein 2 (AtGR-RBP2). NsCP33 may be involved in splicing and/or processing of chloroplast RNA's. AtCP31A, also called RNA-binding protein 1/2/3 (AtRBP33), or RNA-binding protein CP31A, or RNA-binding protein RNP-T, or RNA-binding protein cp31, is required for specific RNA editing events in chloroplasts and stabilizes specific chloroplast mRNAs, as well as for normal chloroplast development under cold stress conditions by stabilizing transcripts of numerous mRNAs under these conditions. CP31A may modulate telomere replication through RNA binding domains. AtGR-RBP2, also called AtRBG2, or glycine-rich protein 2 (AtGRP2), or mitochondrial RNA-binding protein 1a (At-mRBP1a), plays a role in RNA transcription or processing during stress. It binds RNAs and DNAs sequence with a preference to single-stranded nucleic acids. AtGR-RBP2 displays strong affinity to poly(U) sequence. It exerts cold and freezing tolerance, probably by exhibiting an RNA chaperone activity during the cold and freezing adaptation process. Some members in this family contain two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The model corresponds to the second RRM motif.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 1720367449   3 NLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd21608    30 KVITDRETGRSRGFGFVTFSTAEAAEAAIDALNGKELDGRSIVVNEA 76

RNA recognition motif 1 (RRM1) found in RNA-binding protein 28 (RBM28) and similar proteins; This subfamily corresponds to the RRM1 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 1720367449   6 TDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFATRR 52
Cdd:cd12413    33 KDKGKDKCRGFGYVTFALAEDAQRALEEVKGKKFGGRKIKVELAKKK 79

RNA recognition motif in type II polyadenylate-binding proteins; This subfamily corresponds to the RRM of type II polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 2 (PABP-2 or PABPN1), embryonic polyadenylate-binding protein 2 (ePABP-2 or PABPN1L) and similar proteins. PABPs are highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in the 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. ePABP-2 is predominantly located in the cytoplasm and PABP-2 is located in the nucleus. In contrast to the type I PABPs containing four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), the type II PABPs contains a single highly-conserved RRM. This subfamily also includes Saccharomyces cerevisiae RBP29 (SGN1, YIR001C) gene encoding cytoplasmic mRNA-binding protein Rbp29 that binds preferentially to poly(A). Although not essential for cell viability, Rbp29 plays a role in modulating the expression of cytoplasmic mRNA. Like other type II PABPs, Rbp29 contains one RRM only.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDwFDGKEFHGNIIKVS 47
Cdd:cd12306    29 VTILCDKFTGQPKGFAYIEFVDKSSVENALL-LNESEFRGRQIKVT 73

RNA recognition motif (RRM) found in eukaryotic translation initiation factor 4H (eIF-4H) and similar proteins; This subfamily corresponds to the RRM of eIF-4H, also termed Williams-Beuren syndrome chromosomal region 1 protein, which, together with elf-4B/eIF-4G, serves as the accessory protein of RNA helicase eIF-4A. eIF-4H contains a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It stimulates protein synthesis by enhancing the helicase activity of eIF-4A in the initiation step of mRNA translation.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDwFDGKEFHGNIIKVSFATRR 52
Cdd:cd12401    34 VRLVRDRETDKFKGFCYVEFEDLESLKEALE-YDGALFEDRPLRVDIAEGR 83

RNA recognition motif 3 (RRM3) found in RNA-binding protein 19 (RBM19) and RNA recognition motif 2 found in multiple RNA-binding domain-containing protein 1 (MRD1); This subfamily corresponds to the RRM3 of RBM19 and RRM2 of MRD1. RBM19, also termed RNA-binding domain-1 (RBD-1), is a nucleolar protein conserved in eukaryotes involved in ribosome biogenesis by processing rRNA and is essential for preimplantation development. It has a unique domain organization containing 6 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). MRD1 is encoded by a novel yeast gene MRD1 (multiple RNA-binding domain). It is well conserved in yeast and its homologs exist in all eukaryotes. MRD1 is present in the nucleolus and the nucleoplasm. It interacts with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs (snoRNAs). It is essential for the initial processing at the A0-A2 cleavage sites in the 35 S pre-rRNA. MRD1 contains 5 conserved RRMs, which may play an important structural role in organizing specific rRNA processing events.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 1720367449   7 DKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKV 46
Cdd:cd12316    34 DKQTKRSKGFAFVLFVIPEDAVKAYQELDGSIFQGRLLHV 73

RNA recognition motif 2 (RRM2) found in yeast multiple RNA-binding domain-containing protein 1 (MRD1) and similar proteins; This subgroup corresponds to the RRM2 of MRD1 which is encoded by a novel yeast gene MRD1 (multiple RNA-binding domain). It is well-conserved in yeast and its homologs exist in all eukaryotes. MRD1 is present in the nucleolus and the nucleoplasm. It interacts with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs (snoRNAs). It is essential for the initial processing at the A0-A2 cleavage sites in the 35 S pre-rRNA. MRD1 contains 5 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), which may play an important structural role in organizing specific rRNA processing events.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKV 46
Cdd:cd12566    32 VHVPIDKKTKKSKGFAYVLFLDPEDAVQAYNELDGKVFQGRLIHI 76

RNA recognition motif 1 (RRM1) found in the c-myc gene single-strand binding proteins (MSSP) family; This subfamily corresponds to the RRM1 of c-myc gene single-strand binding proteins (MSSP) family, including single-stranded DNA-binding protein MSSP-1 (also termed RBMS1 or SCR2) and MSSP-2 (also termed RBMS2 or SCR3). All MSSP family members contain two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), both of which are responsible for the specific DNA binding activity. Both, MSSP-1 and -2, have been identified as protein factors binding to a putative DNA replication origin/transcriptional enhancer sequence present upstream from the human c-myc gene in both single- and double-stranded forms. Thus, they have been implied in regulating DNA replication, transcription, apoptosis induction, and cell-cycle movement, via the interaction with c-MYC, the product of protooncogene c-myc. Moreover, the family includes a new member termed RNA-binding motif, single-stranded-interacting protein 3 (RBMS3), which is not a transcriptional regulator. RBMS3 binds with high affinity to A/U-rich stretches of RNA, and to A/T-rich DNA sequences, and functions as a regulator of cytoplasmic activity. In addition, a putative meiosis-specific RNA-binding protein termed sporulation-specific protein 5 (SPO5, or meiotic RNA-binding protein 1, or meiotically up-regulated gene 12 protein), encoded by Schizosaccharomyces pombe Spo5/Mug12 gene, is also included in this family. SPO5 is a novel meiosis I regulator that may function in the vicinity of the Mei2 dot.

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1720367449   6 TDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHG 41
Cdd:cd12243    34 IDKQTNKCKGYGFVDFDSPEAALKAIEGLNGRGVQA 69

RNA recognition motif 1 (RRM1) found in HIV Tat-specific factor 1 (Tat-SF1) and similar proteins; This subfamily corresponds to the RRM1 of Tat-SF1 and CUS2. Tat-SF1 is the cofactor for stimulation of transcriptional elongation by human immunodeficiency virus-type 1 (HIV-1) Tat. It is a substrate of an associated cellular kinase. Tat-SF1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a highly acidic carboxyl-terminal half. The family also includes CUS2, a yeast homolog of human Tat-SF1. CUS2 interacts with U2 RNA in splicing extracts and functions as a splicing factor that aids assembly of the splicing-competent U2 snRNP in vivo. CUS2 also associates with PRP11 that is a subunit of the conserved splicing factor SF3a. Like Tat-SF1, CUS2 contains two RRMs as well.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1720367449   2 INLYTDKDtGKPKGEATVSFDDPPSAKAAIDWFDGKE-FHGNIIKVSFAT 50
Cdd:cd12281    39 IKLYRDEN-GNLKGDALCCYLKEESVELALQLLDGTEiGRGYKIHVERAK 87

RNA recognition motif 2 (RRM2) found in squamous cell carcinoma antigen recognized by T-cells 3 (SART3) and similar proteins; This subfamily corresponds to the RRM2 of SART3, also termed Tat-interacting protein of 110 kDa (Tip110), is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. It is involved in the regulation of mRNA splicing probably via its complex formation with RNA-binding protein with a serine-rich domain (RNPS1), a pre-mRNA-splicing factor. SART3 has also been identified as a nuclear Tat-interacting protein that regulates Tat transactivation activity through direct interaction and functions as an important cellular factor for HIV-1 gene expression and viral replication. In addition, SART3 is required for U6 snRNP targeting to Cajal bodies. It binds specifically and directly to the U6 snRNA, interacts transiently with the U6 and U4/U6 snRNPs, and promotes the reassembly of U4/U6 snRNPs after splicing in vitro. SART3 contains an N-terminal half-a-tetratricopeptide repeat (HAT)-rich domain, a nuclearlocalization signal (NLS) domain, and two C-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                          10        20        30
                  ....*....|....*....|....*....|....*..
gi 1720367449  11 GKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVS 47
Cdd:cd12392    40 GKPKGLAYVEYENEADASQAVLKTDGTEIKDHTISVA 76

RNA recognition motif 4 (RRM4) found in vertebrate nucleolin; This subfamily corresponds to the RRM4 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1720367449   6 TDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd12406    31 TDRDTGSSKGFGFVDFSSEEDAKAAKEAMEDGEIDGNKVTLDFA 74

RNA recognition motif 2 (RRM2) found in Arabidopsis thaliana phragmoplastin interacting protein 1 (PHIP1) and similar proteins; The CD corresponds to the RRM2 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDwFDGKEFHGNIIKVS 47
Cdd:cd12272    29 VRLHTDKETGEFKGYGHVEFADEESLDAALK-LAGTKLCGRPIRVD 73

RNA recognition motif (RRM) found in cold inducible RNA binding protein (CIRBP), RNA binding motif protein 3 (RBM3) and similar proteins; This subfamily corresponds to the RRM domain of two structurally related heterogenous nuclear ribonucleoproteins, CIRBP (also termed CIRP or A18 hnRNP) and RBM3 (also termed RNPL), both of which belong to a highly conserved cold shock proteins family. The cold shock proteins can be induced after exposure to a moderate cold-shock and other cellular stresses such as UV radiation and hypoxia. CIRBP and RBM3 may function in posttranscriptional regulation of gene expression by binding to different transcripts, thus allowing the cell to response rapidly to environmental signals. However, the kinetics and degree of cold induction are different between CIRBP and RBM3. Tissue distribution of their expression is different. CIRBP and RBM3 may be differentially regulated under physiological and stress conditions and may play distinct roles in cold responses of cells. CIRBP, also termed glycine-rich RNA-binding protein CIRP, is localized in the nucleus and mediates the cold-induced suppression of cell cycle progression. CIRBP also binds DNA and possibly serves as a chaperone that assists in the folding/unfolding, assembly/disassembly and transport of various proteins. RBM3 may enhance global protein synthesis and the formation of active polysomes while reducing the levels of ribonucleoprotein complexes containing microRNAs. RBM3 may also serve to prevent the loss of muscle mass by its ability to decrease cell death. Furthermore, RBM3 may be essential for cell proliferation and mitosis. Both, CIRBP and RBM3, contain an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), that is involved in RNA binding, and C-terminal glycine-rich domain (RGG motif) that probably enhances RNA-binding via protein-protein and/or protein-RNA interactions. Like CIRBP, RBM3 can also bind to both RNA and DNA via its RRM domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1720367449   7 DKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd12449    35 DRETQRSRGFGFVTFENPDDAKDAMMAMNGKSLDGRQIRVDQA 77

RNA recognition motif 3 (RRM3) found found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM3 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 the 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. 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1720367449   9 DTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFATRR 52
Cdd:cd12380    37 DSGKSKGFGFVNFENHEAAQKAVEELNGKELNGKKLYVGRAQKK 80

RNA recognition motif in nucleolar protein interacting with the FHA domain of pKI-67 (NIFK) and similar proteins; This subgroup corresponds to the RRM of NIFK and Nop15p. NIFK, also termed MKI67 FHA domain-interacting nucleolar phosphoprotein, or nucleolar phosphoprotein Nopp34, is a putative RNA-binding protein interacting with the forkhead associated (FHA) domain of pKi-67 antigen in a mitosis-specific and phosphorylation-dependent manner. It is nucleolar in interphase but associates with condensed mitotic chromosomes. This family also includes Saccharomyces cerevisiae YNL110C gene encoding ribosome biogenesis protein 15 (Nop15p), also termed nucleolar protein 15. Both, NIFK and Nop15p, contain an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 1720367449   8 KDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVS 47
Cdd:cd12307    35 KKTGKSKGYAFVEFEDPEVAKIVAETMNNYLLFERLLKCK 74

RNA recognition motif 1 (RRM1) found in chloroplastic plastid-specific 30S ribosomal protein 2 (PSRP-2) and similar proteins; PSRP-2, also called chloroplastic 30S ribosomal protein 2, or chloroplastic small ribosomal subunit protein cS22, is a component of the chloroplast ribosome (chloro-ribosome), a dedicated translation machinery responsible for the synthesis of chloroplast genome-encoded proteins, including proteins of the transcription and translation machinery and components of the photosynthetic apparatus. It binds single strand DNA (ssDNA) and RNA in vitro. It exhibits RNA chaperone activity and regulates negatively resistance responses to abiotic stresses during seed germination (e.g. salt, dehydration, and low temperature) and seedling growth (e.g. salt). The family also includes Nicotiana sylvestris chloroplastic 33 kDa ribonucleoprotein (NsCP33) and Arabidopsis thaliana chloroplastic 31 kDa ribonucleoprotein (AtCP31A). NsCP33 may be involved in splicing and/or processing of chloroplast RNA's. AtCP31A, also called RNA-binding protein 1/2/3 (AtRBP33), or RNA-binding protein CP31A, or RNA-binding protein RNP-T, or RNA-binding protein cp31, is required for specific RNA editing events in chloroplasts and stabilizes specific chloroplast mRNAs, as well as for normal chloroplast development under cold stress conditions by stabilizing transcripts of numerous mRNAs under these conditions. CP31A may modulate telomere replication through RNA binding domains. Members in this family contain two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The model corresponds to the first RRM motif.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1720367449   7 DKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd21609    34 DRYTGRSRGFGFVTMGSVEDAKAAIEKLNGTEVGGREIKVNIT 76

RNA recognition motif 1 (RRM1) found in nucleolin-like proteins mainly from plants; This subfamily corresponds to the RRM1 of a group of plant nucleolin-like proteins, including nucleolin 1 (also termed protein nucleolin like 1) and nucleolin 2 (also termed protein nucleolin like 2, or protein parallel like 1). They play roles in the regulation of ribosome synthesis and in the growth and development of plants. Like yeast nucleolin, nucleolin-like proteins possess two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 1720367449   6 TDKDTGKPKGEATVSFDDPPSAKAAIDwFDGKEFHGNIIKVSFATRR 52
Cdd:cd12450    33 MDRDDGRSKGFGHVEFASAESAQKALE-KSGQDLGGREIRLDLANER 78

RNA recognition motif (RRM) found in transformer-2 protein homolog TRA2-alpha, TRA2-beta and similar proteins; This subfamily corresponds to the RRM of two mammalian homologs of Drosophila transformer-2 (Tra2), TRA2-alpha, TRA2-beta (also termed SFRS10), and similar proteins found in eukaryotes. TRA2-alpha is a 40-kDa serine/arginine-rich (SR) protein that specifically binds to gonadotropin-releasing hormone (GnRH) exonic splicing enhancer on exon 4 (ESE4) and is necessary for enhanced GnRH pre-mRNA splicing. It strongly stimulates GnRH intron A excision in a dose-dependent manner. In addition, TRA2-alpha can interact with either 9G8 or SRp30c, which may also be crucial for ESE-dependent GnRH pre-mRNA splicing. 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. Both, TRA2-alpha and TRA2-beta, 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSFA 49
Cdd:cd12363    31 VQVVYDQQTGRSRGFGFVYFESVEDAKEAKERLNGQEIDGRRIRVDYS 78

RNA recognition motif 2 (RRM2) found in HIV Tat-specific factor 1 (Tat-SF1) and similar proteins; This subfamily corresponds to the RRM2 of Tat-SF1 and CUS2. Tat-SF1 is the cofactor for stimulation of transcriptional elongation by human immunodeficiency virus-type 1 (HIV-1) Tat. It is a substrate of an associated cellular kinase. Tat-SF1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a highly acidic carboxyl-terminal half. The family also includes CUS2, a yeast homolog of human Tat-SF1. CUS2 interacts with U2 RNA in splicing extracts and functions as a splicing factor that aids assembly of the splicing-competent U2 snRNP in vivo. CUS2 also associates with PRP11 that is a subunit of the conserved splicing factor SF3a. Like Tat-SF1, CUS2 contains two RRMs as well.

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1720367449  13 PKGEATVSFDDPPSAKAAIDWFDGKEFHGNIIKVSF 48
Cdd:cd12282    49 PDGVASVKFKEPEEADKCIQALNGRWFAGRKLEAET 84

RNA recognition motif (RRM) found in Saccharomyces cerevisiae nucleolar protein 6 (Nop6) and similar proteins; This subfamily corresponds to the RRM of Nop6, also known as Ydl213c, a component of 90S pre-ribosomal particles in yeast S. cerevisiae. It is enriched in the nucleolus and is required for 40S ribosomal subunit biogenesis. Nop6 is a non-essential putative RNA-binding protein with two N-terminal putative nuclear localisation sequences (NLS-1 and NLS-2) and an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It binds to the pre-rRNA early during transcription and plays an essential role in pre-rRNA processing.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1720367449   2 INLYTDKDTGKPKGEATVSFDDPPSAKAAIDwFDGKEFHGNIIKV 46
Cdd:cd12400    30 VRLLTDKKTGKSKGCAFVEFDNQKALQKALK-LHHTSLGGRKINV 73