Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  19 PNLAVREEIDGQWGDSGIIPCTYAPSPEYVEETVVW-----YFSGNAILRlvDSV-PHTLVNKYRGRISLSRSHPGDVSL 92
Cdd:cd16089     1 PILEGPESITGPWKGSVNLPCTYVPEEGYTQVLVKWlvqrdSDPVTIFLR--DSSgDHIQQAKYRGRLEVSKDTPGDVSL 78

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1694576069  93 RINDLQMMDKGQYTCEVVWRSkQSNDKIHEDAITKLNVIK 132
Cdd:cd16089    79 QLDTLEMDDRGHYTCQVTWQT-PDGNLIVREKTTELRVQK 117

Immunoglobulin variable (IgV)-like domain in complement receptor of the immunoglobulin superfamily (CRIg); The members here are composed of the immunoglobulin variable (IgV) region of the complement receptor of the immunoglobulin superfamily (CRIg). The N-terminal domain of CRIg (also known as Z39Ig and V-set and Ig domain-containing 4 (VSIG4) belongs to the IgV family of immunoglobulin-like domains while the C-terminal domain of CRIg belongs to the IgC family of immunoglobulin-like domains. Like all members of this family, the CRIg domain contains two beta-sheets: one composed of strands A', G, F, C, C' and C", and the other of strands B, E and D. The complement system is an important part of the innate immune system and is required for removal of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitment of factor B, initiates formation of the alternative pathway convertases. CRIg, a complement receptor expressed on macrophages, binds to C3b and iC3b mediating phagocytosis of the particles. It is also a potent inhibitor of the alternative pathway convertases and a negative regulator of T cell activation. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, such as, T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, such as, butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  19 PNLAVREEIDGQWGDSGIIPCTYAPSPEYVEETVVW-----YFSGNAILRlvDSV-PHTLVNKYRGRISLSRSHPGDVSL 92
Cdd:cd16089     1 PILEGPESITGPWKGSVNLPCTYVPEEGYTQVLVKWlvqrdSDPVTIFLR--DSSgDHIQQAKYRGRLEVSKDTPGDVSL 78

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1694576069  93 RINDLQMMDKGQYTCEVVWRSkQSNDKIHEDAITKLNVIK 132
Cdd:cd16089    79 QLDTLEMDDRGHYTCQVTWQT-PDGNLIVREKTTELRVQK 117

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  157 PNLVVREeidgqwGDSGIIPCTYAPSPEYveeTVVWYFSGKAilrlvdsvphtlVIKYRGRISLSRSHpGDVSLRINDLQ 236
Cdd:smart00410   2 PSVTVKE------GESVTLSCEASGSPPP---EVTWYKQGGK------------LLAESGRFSVSRSG-STSTLTISNVT 59

                           90       100       110
                   ....*....|....*....|....*....|..
gi 1694576069  237 MMDKGQYTCEVvwrskqSNDQIHEDAITKLNV 268
Cdd:smart00410  60 PEDSGTYTCAA------TNSSGSASSGTTLTV 85

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  25 EEIDGQWGDSGIIPCTYAPSPEYVEETVVWYF--SGNAILRLVD-SVPHTLVNKYRGRISLSRSHP-GDVSLRINDLQMM 100
Cdd:pfam07686   4 REVTVALGGSVTLPCTYSSSMSEASTSVYWYRqpPGKGPTFLIAyYSNGSEEGVKKGRFSGRGDPSnGDGSLTIQNLTLS 83

                          90       100       110
                  ....*....|....*....|....*....|
gi 1694576069 101 DKGQYTCEVVwrskqSNDKIHEDAITKLNV 130
Cdd:pfam07686  84 DSGTYTCAVI-----PSGEGVFGKGTRLTV 108

Immunoglobulin variable (IgV)-like domain in complement receptor of the immunoglobulin superfamily (CRIg); The members here are composed of the immunoglobulin variable (IgV) region of the complement receptor of the immunoglobulin superfamily (CRIg). The N-terminal domain of CRIg (also known as Z39Ig and V-set and Ig domain-containing 4 (VSIG4) belongs to the IgV family of immunoglobulin-like domains while the C-terminal domain of CRIg belongs to the IgC family of immunoglobulin-like domains. Like all members of this family, the CRIg domain contains two beta-sheets: one composed of strands A', G, F, C, C' and C", and the other of strands B, E and D. The complement system is an important part of the innate immune system and is required for removal of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitment of factor B, initiates formation of the alternative pathway convertases. CRIg, a complement receptor expressed on macrophages, binds to C3b and iC3b mediating phagocytosis of the particles. It is also a potent inhibitor of the alternative pathway convertases and a negative regulator of T cell activation. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, such as, T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, such as, butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  19 PNLAVREEIDGQWGDSGIIPCTYAPSPEYVEETVVW-----YFSGNAILRlvDSV-PHTLVNKYRGRISLSRSHPGDVSL 92
Cdd:cd16089     1 PILEGPESITGPWKGSVNLPCTYVPEEGYTQVLVKWlvqrdSDPVTIFLR--DSSgDHIQQAKYRGRLEVSKDTPGDVSL 78

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1694576069  93 RINDLQMMDKGQYTCEVVWRSkQSNDKIHEDAITKLNVIK 132
Cdd:cd16089    79 QLDTLEMDDRGHYTCQVTWQT-PDGNLIVREKTTELRVQK 117

Immunoglobulin (Ig)-like domain of human cartilage link protein (LP), and similar domains; The members here are composed of the immunoglobulin (Ig)-like domain similar to that found in human cartilage link protein (LP; also called hyaluronan and proteoglycan link protein). In cartilage, chondroitin-keratan sulfate proteoglycan (CSPG), aggrecan, forms cartilage link protein stabilized aggregates with hyaluronan (HA). These aggregates contribute to the tissue's load bearing properties. Aggregates having other CSPGs substituting for aggrecan may contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  22 AVREEIDGQWGDSGIIPCTY-------APS----------PEYVEETVVWYFSGNAilrlvdsvpHTLVNKYRGRISLSR 84
Cdd:cd05877     2 TVQAKVFSHRGGNVTLPCRYhyepelsAPRkirvkwtkleVDYAKEEDVLVAIGTR---------HKSYGSYQGRVFLRR 72

                          90       100
                  ....*....|....*....|....*.
gi 1694576069  85 SHPGDVSLRINDLQMMDKGQYTCEVV 110
Cdd:cd05877    73 ADDLDASLVITDLRLEDYGRYRCEVI 98

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  157 PNLVVREeidgqwGDSGIIPCTYAPSPEYveeTVVWYFSGKAilrlvdsvphtlVIKYRGRISLSRSHpGDVSLRINDLQ 236
Cdd:smart00410   2 PSVTVKE------GESVTLSCEASGSPPP---EVTWYKQGGK------------LLAESGRFSVSRSG-STSTLTISNVT 59

                           90       100       110
                   ....*....|....*....|....*....|..
gi 1694576069  237 MMDKGQYTCEVvwrskqSNDQIHEDAITKLNV 268
Cdd:smart00410  60 PEDSGTYTCAA------TNSSGSASSGTTLTV 85

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  25 EEIDGQWGDSGIIPCTYAPSPEYVEETVVWYF--SGNAILRLVD-SVPHTLVNKYRGRISLSRSHP-GDVSLRINDLQMM 100
Cdd:pfam07686   4 REVTVALGGSVTLPCTYSSSMSEASTSVYWYRqpPGKGPTFLIAyYSNGSEEGVKKGRFSGRGDPSnGDGSLTIQNLTLS 83

                          90       100       110
                  ....*....|....*....|....*....|
gi 1694576069 101 DKGQYTCEVVwrskqSNDKIHEDAITKLNV 130
Cdd:pfam07686  84 DSGTYTCAVI-----PSGEGVFGKGTRLTV 108

First immunoglobulin variable (IgV) domain of poliovirus receptor (PVR, also known as CD155 and necl-5), and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of poliovirus receptor (PVR, also known as CD155 and nectin-like protein 5 (necl-5)). Poliovirus (PV) binds to its cellular receptor (PVR/CD155) to initiate infection. CD155 is a membrane-anchored, single-span glycoprotein; its extracellular region has three Ig-like domains. There are four different isotypes of CD155 (referred to as alpha, beta, gamma, and delta), that result from alternate splicing of the CD155 mRNA, and have identical extracellular domains. CD155-beta and CD155-gamma are secreted; CD155-alpha and CD155-delta are membrane-bound and function as PV receptors. The virus recognition site is contained in the amino-terminal domain, D1. Having the virus attachment site on the receptor distal from the plasma membrane may be important for successful initiation of infection of cells by the virus. CD155 binds in the poliovirus "canyon" with a footprint similar to that of the intercellular adhesion molecule-1 receptor on human rhinoviruses. This group also includes the first Ig-like domain of nectin-1 (also known as poliovirus receptor related protein(PVRL)1; CD111), nectin-3 (also known as PVRL 3), nectin-4 (also known as PVRL4; LNIR receptor)and DNAX accessory molecule 1 (DNAM-1; CD226).

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  23 VREEIDGQWGDSGIIPCTYAPS-PEYVEEtVVWYFSGNAILRLVD--------SVPhtlvNKYRGRISLSRSHPG--DVS 91
Cdd:cd05718     5 VPTEVTGFLGGSVTLPCSLTSPgTTKITQ-VTWMKIGAGSSQNVAvfhpqygpSVP----NPYAERVEFLAARLGlrNAT 79

                          90
                  ....*....|....*....
gi 1694576069  92 LRINDLQMMDKGQYTCEVV 110
Cdd:cd05718    80 LRIRNLRVEDEGNYICEFA 98

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069 163 EEIDGQWGDSGIIPCTYAPSPEYVEETVVWYF--SGKAILRLVD-SVPHTLVIKYRGRISLSRSHP-GDVSLRINDLQMM 238
Cdd:pfam07686   4 REVTVALGGSVTLPCTYSSSMSEASTSVYWYRqpPGKGPTFLIAyYSNGSEEGVKKGRFSGRGDPSnGDGSLTIQNLTLS 83

                          90       100       110
                  ....*....|....*....|....*....|
gi 1694576069 239 DKGQYTCEVVwrskqSNDQIHEDAITKLNV 268
Cdd:pfam07686  84 DSGTYTCAVI-----PSGEGVFGKGTRLTV 108

Immunoglobulin Variable (IgV) domain of B7-H4; The members here are composed of the immunoglobulin variable (IgV) domain of B7-H4 (also known as B7-S1, B7x, or Vtcn1). B7-H4 is one of the B7 family of immune-regulatory ligands that act as negative regulators of T cell function; it contains one IgV domain and one IgC domain. The B7-family consists of structurally related cell-surface protein ligands, which bind to receptors on lymphocytes that regulate immune responses. The binding of B7-H4 to unidentified receptors results in the inhibition of TCR-mediated T cell proliferation, cell-cycle progression and IL-2 production. As a co-inhibitory molecule, B7-H4 is widely expressed in tumor tissues and its expression is significantly associated with poor prognosis in human cancers such as glioma, pancreatic cancer, oral squamous cell carcinoma, renal cell carcinoma, and lung cancer.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069 167 GQWGDSGIIPCTYAPSPEYVEETVVW-----------YFSGKAilRLVDSVPhtlviKYRGRISL--SRSHPGDVSLRIN 233
Cdd:cd20984     9 GNIGEDGILSCTFTPDIKLSDIVIQWlkegdsglvheFKEGKD--ELSRQSP-----MFRGRTSLfaDQVHVGNASLRLK 81

                          90
                  ....*....|....
gi 1694576069 234 DLQMMDKGQYTCEV 247
Cdd:cd20984    82 NVQLTDAGTYLCII 95

Immunoglobulin Variable (IgV) domain in HERV-H LTR-associating 2 (HHLA2); The members here are composed of the immunoglobulin variable (IgV) region in HERV-H LTR-associating 2 (HHLA2; also known as B7-H7/B7 homolog 7). HHLA2 is a member of the B7 family of immune regulatory proteins. Mature human HHLA2 consists of an extracellular domain (ECD) with three immunoglobulin-like domains, a transmembrane segment, and a cytoplasmic domain. HHLA2 is widely expressed in human cancers including non-small cell lung carcinoma (NSCLS), triple negative breast cancer (TNBC), and melanoma, but has limited expression on normal tissues. Interestingly, unlike other members of B7 family, HHLA2 is not expressed in mice or rats. HHLA2 functions as a T cell coinhibitory molecules as it inhibits the proliferation of activated CD4(+) and CD8(+) T cells and their cytokine production. Furthermore, HHLA2 is constitutively expressed on the surface of human monocytes and is induced on B cells after stimulation, however it is not inducible on T cells.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  26 EIDGQWGDSGIIPCTYAPSPEYVeetVVWYfSGNAILRLvdsvpHTLV----------NKYRGRISLSRSH--PGDVSLR 93
Cdd:cd16091     6 IVVCLLSEDCILPCSFTPGSEVV---IHWY-KQDSDIKV-----HSYYygkdqlesqdQRYRNRTSLFKDQisNGNASLL 76

                          90       100       110
                  ....*....|....*....|....*....|....*..
gi 1694576069  94 INDLQMMDKGQYTCEVvwrskqSNDKIHEDAITKLNV 130
Cdd:cd16091    77 LRRVQLQDEGRYKCYT------STIIGNQESFVNLKV 107

Immunoglobulin Variable (IgV) domain in HERV-H LTR-associating 2 (HHLA2); The members here are composed of the immunoglobulin variable (IgV) region in HERV-H LTR-associating 2 (HHLA2; also known as B7-H7/B7 homolog 7). HHLA2 is a member of the B7 family of immune regulatory proteins. Mature human HHLA2 consists of an extracellular domain (ECD) with three immunoglobulin-like domains, a transmembrane segment, and a cytoplasmic domain. HHLA2 is widely expressed in human cancers including non-small cell lung carcinoma (NSCLS), triple negative breast cancer (TNBC), and melanoma, but has limited expression on normal tissues. Interestingly, unlike other members of B7 family, HHLA2 is not expressed in mice or rats. HHLA2 functions as a T cell coinhibitory molecules as it inhibits the proliferation of activated CD4(+) and CD8(+) T cells and their cytokine production. Furthermore, HHLA2 is constitutively expressed on the surface of human monocytes and is induced on B cells after stimulation, however it is not inducible on T cells.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069 164 EIDGQWGDSGIIPCTYAPSPEYVeetVVW-----------YFSGKAILRLVDSvphtlviKYRGRISLSRSH--PGDVSL 230
Cdd:cd16091     6 IVVCLLSEDCILPCSFTPGSEVV---IHWykqdsdikvhsYYYGKDQLESQDQ-------RYRNRTSLFKDQisNGNASL 75

                          90       100       110
                  ....*....|....*....|....*....|....*...
gi 1694576069 231 RINDLQMMDKGQYTCEVvwrskqSNDQIHEDAITKLNV 268
Cdd:cd16091    76 LLRRVQLQDEGRYKCYT------STIIGNQESFVNLKV 107

Immunoglobulin (Ig)-like domain of myelin oligodendrocyte glycoprotein (MOG); The members here are composed of the immunoglobulin (Ig)-like domain of myelin oligodendrocyte glycoprotein (MOG). MOG, a minor component of the myelin sheath, is an important CNS-specific autoantigen, linked to the pathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). It is a transmembrane protein having an extracellular Ig domain. MOG is expressed in the CNS on the outermost lamellae of the myelin sheath, and on the surface of oligodendrocytes, and may participate in the completion, compaction, and/or maintenance of myelin. This group also includes butyrophilin (BTN). BTN is the most abundant protein in bovine milk-fat globule membrane (MFGM).

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069 213 KYRGRISLSR---SHpGDVSLRINDLQMMDKGQYTCevVWRSkqsnDQIHEDAITKLNVI 269
Cdd:cd05713    62 EYRGRTELLKdaiAE-GSVALRIHNVRPSDEGQYTC--FFRS----GSFYEEATLELKVA 114

Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1694576069 175 IPCTYAPSPEYveeTVVWYFSGKAILRlvdsvphtlvikyrGRISLSRSHPGDVSLRINDLQMMDKGQYTCEV 247
Cdd:cd00096     3 LTCSASGNPPP---TITWYKNGKPLPP--------------SSRDSRRSELGNGTLTISNVTLEDSGTYTCVA 58

Immunoglobulin Variable region-containing chitin-binding proteins; an immunoglobulin V-set domain; The members here are composed of the immunoglobulin variable (IgV) region-containing chitin-binding proteins (VCBPs). VCBPs are secreted, immune-type molecules that have been identified in both amphioxus and sea squirt (Ciona intestinalis). VCBPs, which consist of a leader peptide, two tandem N-terminal immunoglobulin V-type domains and a single C-terminal chitin-binding domain, belong to a multigene family encoding secreted proteins. The VCBPs were identified first in the cephalochordate Branchiostoma floridae and show structural similarities with V-type domains of immunoglobulins and T cell receptors, suggesting that VCBPs represent a unique gut-associated form of innate immune proteins. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, such as, T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, such as, butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. This group belongs to the V-set of IgSF domains, having A, B, E and D strands in one beta-sheet and A', G, F, C, C' and C" in the other.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069 164 EIDGQWGDSGIIPCTYAPSPEYVEETVVW-----------YFSGKAILRLVDSVPHTLVIKYRGRISL-SRSHPgdvSLR 231
Cdd:cd20963    11 RTDPTWGNRVELPCSYTISPAAQPPTITWlkgisvdraevVFKGFKYWNETSSSGEVYFGDYAGRASVaSLTQP---TLV 87

                          90
                  ....*....|....*.
gi 1694576069 232 INDLQMMDKGQYTCEV 247
Cdd:cd20963    88 LTDLKFDDWGRYWCRV 103

Immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), versican; The members here are composed of the immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), versican. In CSPGs, the Ig-like domain is followed by hyaluronan (HA)-binding tandem repeats, and a C-terminal region with epidermal growth factor-like, lectin-like, and complement regulatory protein-like domains. Separating these N- and C-terminal regions is a nonhomologous glycosaminoglycan attachment region. In cartilage, the CSPG aggrecan (not included in this group) forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Like aggrecan, versican has a wide distribution in connective tissue and extracellular matrices. Aggregates having other CSPGs substituting for aggrecan may contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 1694576069 214 YRGRISLSrSHP---GDVSLRINDLQMMDKGQYTCEVVWRSKQSNDQIHED 261
Cdd:cd05901    73 YMGRVSVP-SHPedqGDASLTIVKLRASDAGVYRCEVMHGIEDTQDTVSLD 122

Immunoglobulin Variable (IgV) domain at the N-terminus of CD33 and related Siglecs (sialic acid-binding Ig-like lectins); The members here are composed of the immunoglobulin (Ig) domain at the N-terminus of Cluster of Differentiation (CD) 33 and related Siglecs (sialic acid-binding Ig-like lectins). Siglec refers to a structurally related protein family that specifically recognizes sialic acid in oligosaccharide chains of glycoproteins and glycolipids. Siglecs are type I transmembrane proteins, organized as an extracellular module composed of Ig-like domains, an N-terminal variable set of Ig-like carbohydrate recognition domains, and 1 to 16 constant Ig-like domains, followed by transmembrane and short cytoplasmic domains. Human Siglecs are classified into two subgroups, one subgroup is comprised of sialoadhesin (Siglec-1), CD22 (Siglec-2), and MAG, the other subgroup is comprised of CD33-related Siglecs which include CD33 (Siglec-3) and human Siglecs 5-11.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069  20 NLAVREEIDGQWGDSGIIPCTY---APSPEYVEETVVWYFSGNAILR---LVDSVPHTLVNK-YRGRISLSrshpGDV-- 90
Cdd:cd05712     2 GLQMPKSVTVQEGLCVLIPCSFsypADYWVSNPVHGYWYRGGPYPKYrppVATNNRTREVHEsTQGRFRLL----GDPgk 77

                          90
                  ....*....|....*...
gi 1694576069  91 ---SLRINDLQMMDKGQY 105
Cdd:cd05712    78 kncSLSISDARPEDSGKY 95

Immunoglobulin variable domain (IgV) in Cluster of Differentiation (CD) 86; The members here are composed of the immunoglobulin variable region (IgV) in the Cluster of Differentiation (CD) 86). Glycoproteins B7-1 (also known as cluster of differentiation (CD) 80) and B7-2 (also known as CD86) are expressed on antigen-presenting cells and deliver the co-stimulatory signal through CD28 and CTLA-4 (also known as CD152) on T cells. signaling through CD28 augments the T-cell response, whereas CTLA-4 signaling attenuates it. The CTLA-4 and B7-2 monomers are both two-layer beta-sandwiches that display the chain topology characteristic of the immunoglobulin variable (V-type) domains present in antigen receptors. The front and back sheets of B7-2 are composed of AGFCC'C" and BED strands, respectively. Members of the IgV family are components of immunoglobulin (Ig) and T cell receptors. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. In Ig, each chain is composed of one variable domain (IgV) and one or more constant domains (IgC); these names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. Within the variable domain, there are regions of even more variability called the hypervariable or complementarity-determining regions (CDRs) which are responsible for antigen binding. A predominant feature of most Ig domains is the disulfide bridge connecting 2 beta-sheets with a tryptophan residue packed against the disulfide bond.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1694576069 170 GDSGIIPCTYaPSPE--YVEETVVWY-----------FSGKAILRLVDSvphtlviKYRGRISLSRshpGDVSLRINDLQ 236
Cdd:cd16087     8 NETAYLPCQF-KNPQniSLSELVVFWqdqkklvlyelYLGKEKLDNVNS-------KYIGRTSFDQ---ENWTLQLHNVQ 76

                          90       100       110
                  ....*....|....*....|....*....|...
gi 1694576069 237 MMDKGQYTCEVVWRSKQSNDQIHeDAITKLNVI 269
Cdd:cd16087    77 IKDQGTYQCFIHHKSPKGLVLIH-QMSSELSVI 108