Immunoglobulin Variable (IgV) domain of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4); The members here are composed of the variable(v)-type immunoglobulin (Ig) domain found in cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). CTLA-4 is involved in the regulation of T cell response, acting as an inhibitor of intracellular signaling. CTLA-4 is similar to CD28, a T cell co-receptor protein that recognizes the B7 proteins (CD80 and CD86). CD28 binding of the B7 proteins occurs after the presentation of antigen to the T cell receptor (TCR) via the peptide-MHC complex on the surface of an antigen presenting cell (APC). CTLA-4 also binds the B7 molecules with a higher affinity than does CD28. The B7/CTLA-4 interaction generates inhibitory signals down-regulating the response, and may prevent T cell activation by weak TCR signals. CD28 and CTLA-4 then elicit opposing signals in the regulation of T cell responsiveness and homeostasis. T cell activation leads to increased CTLA-4 gene expression and trafficking of CTLA-4 protein to the cell surface. CTLA-4 is not detected on the T-cell surface until 24 hours after activation. Covalent dimerization of CTLA-4 has been shown to be required for its high binding avidity, although each CTLA-4 monomer contains a binding site for CD80 and CD86.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564368637  39 QVTQPSVVLASSHGVASFPCEYASSHNTDEVRVTVLRQTNDQVTEVCATTFTVKNTLGFLDDPFCSGTFNESRVNLTIQG 118
Cdd:cd05721    1 HVAQPAVVLASSRGVASFVCEYASSGNATEVRVTVLRQADSQMTEVCAATYTMGNELTFLDDSICTGTSSGNQVNLTIQG 80

                         90       100       110
                 ....*....|....*....|....*....|....
gi 564368637 119 LRAADTGLYFCKVELMYPPPYFVGMGNGTQIYVI 152
Cdd:cd05721   81 LRAMDTGLYICKVELMYPPPYYVGMGNGTQIYVI 114

Immunoglobulin Variable (IgV) domain of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4); The members here are composed of the variable(v)-type immunoglobulin (Ig) domain found in cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). CTLA-4 is involved in the regulation of T cell response, acting as an inhibitor of intracellular signaling. CTLA-4 is similar to CD28, a T cell co-receptor protein that recognizes the B7 proteins (CD80 and CD86). CD28 binding of the B7 proteins occurs after the presentation of antigen to the T cell receptor (TCR) via the peptide-MHC complex on the surface of an antigen presenting cell (APC). CTLA-4 also binds the B7 molecules with a higher affinity than does CD28. The B7/CTLA-4 interaction generates inhibitory signals down-regulating the response, and may prevent T cell activation by weak TCR signals. CD28 and CTLA-4 then elicit opposing signals in the regulation of T cell responsiveness and homeostasis. T cell activation leads to increased CTLA-4 gene expression and trafficking of CTLA-4 protein to the cell surface. CTLA-4 is not detected on the T-cell surface until 24 hours after activation. Covalent dimerization of CTLA-4 has been shown to be required for its high binding avidity, although each CTLA-4 monomer contains a binding site for CD80 and CD86.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564368637  39 QVTQPSVVLASSHGVASFPCEYASSHNTDEVRVTVLRQTNDQVTEVCATTFTVKNTLGFLDDPFCSGTFNESRVNLTIQG 118
Cdd:cd05721    1 HVAQPAVVLASSRGVASFVCEYASSGNATEVRVTVLRQADSQMTEVCAATYTMGNELTFLDDSICTGTSSGNQVNLTIQG 80

                         90       100       110
                 ....*....|....*....|....*....|....
gi 564368637 119 LRAADTGLYFCKVELMYPPPYFVGMGNGTQIYVI 152
Cdd:cd05721   81 LRAMDTGLYICKVELMYPPPYYVGMGNGTQIYVI 114

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564368637    54 ASFPCEYASSHNTDEVrVTVLRQTNDQVTEVCAT--TFTVKNTLGFLDDPF-CSGTFNESRVNLTIQGLRAADTGLYFCK 130
Cdd:smart00406   2 VTLSCKFSGSTFSSYY-VSWVRQPPGKGLEWLGYigSNGSSYYQESYKGRFtISKDTSKNDVSLTISNLRVEDTGTYYCA 80

                   .
gi 564368637   131 V 131
Cdd:smart00406  81 V 81

Immunoglobulin Variable (IgV) domain of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4); The members here are composed of the variable(v)-type immunoglobulin (Ig) domain found in cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). CTLA-4 is involved in the regulation of T cell response, acting as an inhibitor of intracellular signaling. CTLA-4 is similar to CD28, a T cell co-receptor protein that recognizes the B7 proteins (CD80 and CD86). CD28 binding of the B7 proteins occurs after the presentation of antigen to the T cell receptor (TCR) via the peptide-MHC complex on the surface of an antigen presenting cell (APC). CTLA-4 also binds the B7 molecules with a higher affinity than does CD28. The B7/CTLA-4 interaction generates inhibitory signals down-regulating the response, and may prevent T cell activation by weak TCR signals. CD28 and CTLA-4 then elicit opposing signals in the regulation of T cell responsiveness and homeostasis. T cell activation leads to increased CTLA-4 gene expression and trafficking of CTLA-4 protein to the cell surface. CTLA-4 is not detected on the T-cell surface until 24 hours after activation. Covalent dimerization of CTLA-4 has been shown to be required for its high binding avidity, although each CTLA-4 monomer contains a binding site for CD80 and CD86.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564368637  39 QVTQPSVVLASSHGVASFPCEYASSHNTDEVRVTVLRQTNDQVTEVCATTFTVKNTLGFLDDPFCSGTFNESRVNLTIQG 118
Cdd:cd05721    1 HVAQPAVVLASSRGVASFVCEYASSGNATEVRVTVLRQADSQMTEVCAATYTMGNELTFLDDSICTGTSSGNQVNLTIQG 80

                         90       100       110
                 ....*....|....*....|....*....|....
gi 564368637 119 LRAADTGLYFCKVELMYPPPYFVGMGNGTQIYVI 152
Cdd:cd05721   81 LRAMDTGLYICKVELMYPPPYYVGMGNGTQIYVI 114

Immunoglobulin Variable (IgV) domain Cluster of Differentiation (CD) 28; The members here are composed of the immunoglobulin variable region (IgV) of Cluster of Differentiation (CD) 28). CD28 is one of the proteins expressed on T cells that provide co-stimulatory signals required for T cell activation and survival. CD28 is the receptor for CD80 (B7.1) and CD86 (B7.2) proteins. CD28 consists of a paired V-set of immunoglobulin (Ig) superfamily domains attached to single-transmembrane domains and cytoplasmic domains that contain the MYPPY motif, which is involved in binding B7.1 or B7.2. CD28 is very similar to CTLA-4 (cytotoxic T-lymphocyte-associated protein 4, also known as CD152 (cluster of differentiation 152)), which is involved in the regulation of T cell response, acting as an inhibitor of intracellular signaling. CTLA-4 also binds the B7 molecules (B7.1 and B7.2) with a higher affinity than does CD28. The B7/CTLA-4 interaction generates inhibitory signals down-regulating the response, and may prevent T cell activation by weak TCR signals. CD28 and CTLA-4 then elicit opposing signals in the regulation of T cell responsiveness and homeostasis. The IgSF is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. The two sheets are linked together by a conserved disulfide bond between B strand and F strand. 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. The N-terminal Ig-like domain of CD28 is a member of the V-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C'-C" in the other. However, each CD28-B7 family member is slightly different, some have an IgV domain which lacks an A' or C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564368637  38 IQVTQpSVVLASSHGVASFPCEYASSHNTDEVRVTvLRQTNDQVTEVCATTFTVKNTLGFLDDP--FCSGTFNESRVNLT 115
Cdd:cd20925    1 ILVKQ-SPMLVVYNNAVNLSCKYTYNLFSKEFRAS-LHKGLDSAVEVCVVYGNYSQQLQVYSNTgfNCDGKLGNESVTFY 78

                         90       100       110
                 ....*....|....*....|....*....|....*..
gi 564368637 116 IQGLRAADTGLYFCKVELMYPPPYFVG-MGNGTQIYV 151
Cdd:cd20925   79 LWNLYVNQTDIYFCKIEVMYPPPYLDNeKSNGTIIHV 115

Immunoglobulin variable (IgV) domain of Natural Killer cell activating receptor NKp30 and similar domains; The members here are composed of the immunoglobulin variable region (IgV) of Natural Killer cell activating receptor NKp30 (also known as Natural Cytotoxicity triggering Receptor 3 (NCR3)) and similar domains. NKp30 Recognizes the N-Terminal IgV Domain of B7-H6. In humans, the activating natural cytotoxicity receptor NKp30 plays a major role in NK cell-mediated tumor cell lysis. NKp30 recognizes the cell-surface protein B7-H6, which is expressed on tumor, but not healthy, cells.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564368637  37 AIQVTQPSVVLASSHGVASFPCEYASSHNTDEV-RVTVLRqtnDQVtevcATTFTVKN-TLGFLDD--PFCSGTF-NESR 111
Cdd:cd20926    1 ALWVSQPPEIRTLEGSSAFLPCSFNASQGRLAIgSVTWFR---DEV----APGKEVRNgTPEFRGRlaPLASSRFlRDHQ 73

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|
gi 564368637 112 VNLTIQGLRAADTGLYFCKVELMyppPYFVGMGNGTQIYV 151
Cdd:cd20926   74 AELHIWDVRGHDAGIYVCRVEVL---GLGVGTGNGTRLVV 110

Immunoglobulin variable domain (IgV) Cluster of Differentiation (CD) 79B; The members here are composed of the immunoglobulin variable domain (IgV) of the Cluster of Differentiation (CD) 79B (also known as CD79b molecule, immunoglobulin-associated beta (Ig-beta), and B29). The B lymphocyte antigen receptor is a multimeric complex that includes the antigen-specific component, surface immunoglobulin (Ig). Surface Ig non-covalently associates with two other proteins, Ig-alpha and Ig-beta, which are necessary for expression and function of the B-cell antigen receptor. This gene encodes the Ig-beta protein of the B-cell antigen component. Alternatively spliced transcript variants encoding different isoforms have been described. 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. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                         10        20        30
                 ....*....|....*....|....*....|....
gi 564368637  97 FLDDPFCSGTFNESRVNLTIQGLRAADTGLYFCK 130
Cdd:cd16096   43 FPEDGRISQTQNGSVYTLTIQNIQYEDNGIYFCQ 76