Immunoglobulin variable domain (IgV) in Cluster of Differentiation (CD) 80; The members here are composed of the immunoglobulin variable region (IgV) in the Cluster of Differentiation (CD) 80). 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 cluster of differentiation 152/CD152) on T cells. signaling through CD28 augments the T-cell response, whereas CTLA-4 signaling attenuates it. CD80 contains two Ig-like domains, an amino-terminal immunoglobulin variable (IgV)-like domain characteristic of adhesion molecules and a membrane proximal immunoglobulin constant (IgC)-like domain similar to the constant domains of antigen receptors. Members of the Ig family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and Major Histocompatibility Complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, and the IgC domain is involved in oligomerization and molecular interactions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437  35 VIHVTKEVKEVATLSCGHNVSVEELAQTRIYWQKEKKMVLTMMSGDMNIWPEYKNRTIFDITNNLSIVILALRPSDEGTY 114
Cdd:cd16086    1 IIQVTKSVKEKALLSCDYNVSVDELAQVRIYWQKDDKMVLTIISGDVKVWPEYKNRTLFDITNNLSIVILALRLSDRGTY 80

                         90       100
                 ....*....|....*....|....*
gi 544416437 115 ECVVLKYEKDAFKREHLAEVMLSVK 139
Cdd:cd16086   81 TCVVQKKERGAYKREHLASVTLSVR 105

Immunoglobulin variable domain (IgV) in Cluster of Differentiation (CD) 80; The members here are composed of the immunoglobulin variable region (IgV) in the Cluster of Differentiation (CD) 80). 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 cluster of differentiation 152/CD152) on T cells. signaling through CD28 augments the T-cell response, whereas CTLA-4 signaling attenuates it. CD80 contains two Ig-like domains, an amino-terminal immunoglobulin variable (IgV)-like domain characteristic of adhesion molecules and a membrane proximal immunoglobulin constant (IgC)-like domain similar to the constant domains of antigen receptors. Members of the Ig family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and Major Histocompatibility Complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, and the IgC domain is involved in oligomerization and molecular interactions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437  35 VIHVTKEVKEVATLSCGHNVSVEELAQTRIYWQKEKKMVLTMMSGDMNIWPEYKNRTIFDITNNLSIVILALRPSDEGTY 114
Cdd:cd16086    1 IIQVTKSVKEKALLSCDYNVSVDELAQVRIYWQKDDKMVLTIISGDVKVWPEYKNRTLFDITNNLSIVILALRLSDRGTY 80

                         90       100
                 ....*....|....*....|....*
gi 544416437 115 ECVVLKYEKDAFKREHLAEVMLSVK 139
Cdd:cd16086   81 TCVVQKKERGAYKREHLASVTLSVR 105

CD80-like C2-set immunoglobulin domain; These domains belong to the immunoglobulin superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437  141 DFPTPSITDFEIPPSNiRRIICSTSGGFPEPHLSWLENGEELNAISTTVSQDPETELYTVSSKLDFNMT---TNHSFMCL 217
Cdd:pfam08205   1 PTIEPPASLLEGEGPE-VVATCSSAGGKPAPRITWYLDGKPLEAAETSSEQDPESGLVTVTSELKLVPSrsdHGQSLTCQ 79

                          90
                  ....*....|
gi 544416437  218 IKYGHLRVNQ 227
Cdd:pfam08205  80 VSYGALRGSI 89

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 544416437   38 VTKEVKEVATLSCgHNVSVEELAQTRIYW-----QKEKKMVLTMMSGDMNIwPEYKNR---TIFDITNNLSIVILALRPS 109
Cdd:pfam07686   6 VTVALGGSVTLPC-TYSSSMSEASTSVYWyrqppGKGPTFLIAYYSNGSEE-GVKKGRfsgRGDPSNGDGSLTIQNLTLS 83

                          90       100
                  ....*....|....*....|....*
gi 544416437  110 DEGTYECVVLKYEKDAFKREHLAEV 134
Cdd:pfam07686  84 DSGTYTCAVIPSGEGVFGKGTRLTV 108

Immunoglobulin variable domain (IgV) in Cluster of Differentiation (CD) 80; The members here are composed of the immunoglobulin variable region (IgV) in the Cluster of Differentiation (CD) 80). 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 cluster of differentiation 152/CD152) on T cells. signaling through CD28 augments the T-cell response, whereas CTLA-4 signaling attenuates it. CD80 contains two Ig-like domains, an amino-terminal immunoglobulin variable (IgV)-like domain characteristic of adhesion molecules and a membrane proximal immunoglobulin constant (IgC)-like domain similar to the constant domains of antigen receptors. Members of the Ig family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and Major Histocompatibility Complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, and the IgC domain is involved in oligomerization and molecular interactions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437  35 VIHVTKEVKEVATLSCGHNVSVEELAQTRIYWQKEKKMVLTMMSGDMNIWPEYKNRTIFDITNNLSIVILALRPSDEGTY 114
Cdd:cd16086    1 IIQVTKSVKEKALLSCDYNVSVDELAQVRIYWQKDDKMVLTIISGDVKVWPEYKNRTLFDITNNLSIVILALRLSDRGTY 80

                         90       100
                 ....*....|....*....|....*
gi 544416437 115 ECVVLKYEKDAFKREHLAEVMLSVK 139
Cdd:cd16086   81 TCVVQKKERGAYKREHLASVTLSVR 105

CD80-like C2-set immunoglobulin domain; These domains belong to the immunoglobulin superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437  141 DFPTPSITDFEIPPSNiRRIICSTSGGFPEPHLSWLENGEELNAISTTVSQDPETELYTVSSKLDFNMT---TNHSFMCL 217
Cdd:pfam08205   1 PTIEPPASLLEGEGPE-VVATCSSAGGKPAPRITWYLDGKPLEAAETSSEQDPESGLVTVTSELKLVPSrsdHGQSLTCQ 79

                          90
                  ....*....|
gi 544416437  218 IKYGHLRVNQ 227
Cdd:pfam08205  80 VSYGALRGSI 89

Second immunoglobulin (Ig)-like domain of nectin-like molcule-1 (Necl-1); member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin (Ig)-like domain of nectin-like molcule-1 (Necl-1; also known as cell adhesion molecule3 (CADM3)). These nectin-like molecules have similar domain structures to those of nectins. At least five nectin-like molecules have been identified (Necl-1 through Necl-5). These have an extracellular region containing three Ig-like domains, one transmembrane region, and one cytoplasmic region. The N-terminal Ig-like domain of the extracellular region belongs to the V-type subfamily of Ig domains is essential to cell-cell adhesion and plays a part in the interaction with the envelope glycoprotein D of various viruses. Necl-1 and Necl-2 have Ca(2+)-independent homophilic and heterophilic cell-cell adhesion activity. Necl-1 is specifically expressed in neural tissue and is important to the formation of synapses, axon bundles, and myelinated axons. Necl-2 is expressed in a wide variety of tissues and is a putative tumour suppressor gene which is downregulated in aggressive neuroblastoma. Ig domains are likely to participate in ligand binding and recognition.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437 145 PSITDFE--IPPSNIRRIICSTSGGFPEPHLSWLENGEELNAISTTVSQDPETELYTVSSKLDFNMTTNH---SFMCLIK 219
Cdd:cd07705    7 PQITGYEsaFKEKDKAKLRCTSSGSKPAANIKWRKGDQELEGAPTSVQEDGNGKTFTVSSSVEFQVTREDdgaEITCSVG 86

                 ....*
gi 544416437 220 YGHLR 224
Cdd:cd07705   87 HESLH 91

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 544416437  44 EVATLSCGH----NVSVEELAqtrIYWQKEKKMVL-TMMSGD---MNIWPEYKNRTIFDiTNNLSIVILALRPSDEGTYE 115
Cdd:cd16087    9 ETAYLPCQFknpqNISLSELV---VFWQDQKKLVLyELYLGKeklDNVNSKYIGRTSFD-QENWTLQLHNVQIKDQGTYQ 84

                 ...
gi 544416437 116 CVV 118
Cdd:cd16087   85 CFI 87

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 544416437   38 VTKEVKEVATLSCgHNVSVEELAQTRIYW-----QKEKKMVLTMMSGDMNIwPEYKNR---TIFDITNNLSIVILALRPS 109
Cdd:pfam07686   6 VTVALGGSVTLPC-TYSSSMSEASTSVYWyrqppGKGPTFLIAYYSNGSEE-GVKKGRfsgRGDPSNGDGSLTIQNLTLS 83

                          90       100
                  ....*....|....*....|....*
gi 544416437  110 DEGTYECVVLKYEKDAFKREHLAEV 134
Cdd:pfam07686  84 DSGTYTCAVIPSGEGVFGKGTRLTV 108

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 544416437  46 ATLSCghnvSVEELAQTRIYWQKEKKMVltmmsgdmniwPEYKNRTIFDITNNLSIVILALRPSDEGTYECVV 118
Cdd:cd00096    1 VTLTC----SASGNPPPTITWYKNGKPL-----------PPSSRDSRRSELGNGTLTISNVTLEDSGTYTCVA 58

Second immunoglobulin (Ig)-like domain of nectin-like molecule-3 (Necl-3); member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin (Ig)-like domain of nectin-like molecule-3 (Necl-3; also known as cell adhesion molecule 2 (CADM2)). Nectin-like molecules have similar domain structures to those of nectins. At least five nectin-like molecules have been identified (Necl-1 through Necl-5). These have an extracellular region containing three Ig-like domains, one transmembrane region, and one cytoplasmic region. Necl-3 has been shown to accumulate in tissues of the central and peripheral nervous system where it is expressed in ependymal cells and myelinated axons. It is observed at the interface between the axon shaft and the myelin sheath. Ig domains are likely to participate in ligand binding and recognition.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 544416437 145 PSITDFEIP--PSNIRRIICSTSGGFPEPHLSWLENGEELNAISTTVSQDPETELYTVSSKLDF 206
Cdd:cd05884    8 PQISGFTSPvmEGDHIQLTCKTSGSKPAADIRWFKNDKEVKDVKYLKAEDANRKTFTVSSSLDF 71

Immunoglobulin (Ig)-like domain in the polymeric Ig receptor (pIgR) and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain in the polymeric Ig receptor (pIgR) and similar proteins. pIgR delivers dimeric IgA and pentameric IgM to mucosal secretions. Polymeric immunoglobulin (pIgs) are the first defense against pathogens and toxins. IgA and IgM can form polymers via an 18-residue extension at their C-termini referred to as the tailpiece. pIgR transports pIgs across mucosal epithelia into mucosal secretions. Human pIgR is a glycosylated type I transmembrane protein, comprised of a 620-residue extracellular region, a 23-residue transmembrane region, and a 103-residue cytoplasmic tail. The extracellular region contains five domains that share sequence similarity with Ig variable (v) regions. This group also contains the Ig-like extracellular domains of other receptors such as NK cell receptor Nkp44 and myeloid receptors, among others.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 544416437  38 VTKEVKEVATLSCGHNvsvEELAQTRIYWQKE-KKMVLTMMSGDMnIWPEYKnRTIFDITNN--LSIVILALRPSDEGTY 114
Cdd:cd05716    7 VTGVEGGSVTIQCPYP---PKYASSRKYWCKWgSEGCQTLVSSEG-VVPGGR-ISLTDDPDNgvFTVTLNQLRKEDAGWY 81

                 ....
gi 544416437 115 ECVV 118
Cdd:cd05716   82 WCGV 85

Signal-regulatory protein (SIRP) immunoglobulin-like domain 2; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in Signal-Regulatory Protein (SIRP), domain 2 (C1 repeat 1). The SIRPs belong to the "paired receptors" class of membrane proteins that comprise several genes coding for proteins with similar extracellular regions, but very different transmembrane/cytoplasmic regions with different (activating or inhibitory) signaling potentials. They are commonly on NK cells, but are also on many myeloid cells. Their extracellular region contains three Immunoglobulin superfamily domains, a single V-set and two C1-set IgSF domains. Their cytoplasmic tails contain either ITIMs or transmembrane regions that have positively charged residues that allow an association with adaptor proteins, such as DAP12/KARAP, containing ITAMs. There are 3 distinct SIRP members: alpha, beta, and gamma. SIRP alpha (also known as CD172a or SRC homology 2 domain-containing protein tyrosine phosphatase substrate 1/Shps-1) is a membrane receptor that interacts with a ligand CD47 expressed on many cells and gives an inhibitory signal through immunoreceptor tyrosine-based inhibition motifs in the cytoplasmic region that interact with phosphatases SHP-1 and SHP-2. SIRP beta has a short cytoplasmic region and associates with a transmembrane adapter protein DAP12 containing immunoreceptor tyrosine-based activation motifs to give an activating signal. SIRP gamma contains a very short cytoplasmic region lacking obvious signaling motifs, but also binds CD47, but with much less affinity.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....
gi 544416437 160 IICSTSGGFP-EPHLSWLENGEELNAISTTVSQDPETELYTVSS 202
Cdd:cd05772   22 FTCKSHGFSPrDITLKWFKNGNELSALQTTVFPEGDSVSYSVSS 65