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 154091009   37 LLARVGGQAELSCQVIPPHSVMHMEVRWFR----SGHSQPVYLYRGGHKMseeaaPEYANRTEFvKEAIGEGKVSLRIHN 112
Cdd:pfam07686   6 VTVALGGSVTLPCTYSSSMSEASTSVYWYRqppgKGPTFLIAYYSNGSEE-----GVKKGRFSG-RGDPSNGDGSLTIQN 79

                          90       100       110
                  ....*....|....*....|....*....|
gi 154091009  113 INILDDGPYQCSFNGSG-FIDAAIMNLNVT 141
Cdd:pfam07686  80 LTLSDSGTYTCAVIPSGeGVFGKGTRLTVL 109

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 154091009  31 TTPTRHLLARVGGQAELSCQVIPPHSVMHMEVRWFRSGHSQPVYLYRGGHKMSEEAAPEYANRTEFVKEAIGEGKVSLRI 110
Cdd:cd20984    1 TVTAKHLAGNIGEDGILSCTFTPDIKLSDIVIQWLKEGDSGLVHEFKEGKDELSRQSPMFRGRTSLFADQVHVGNASLRL 80

                         90
                 ....*....|...
gi 154091009 111 HNINILDDGPYQC 123
Cdd:cd20984   81 KNVQLTDAGTYLC 93

Immunoglobulin Variable (IgV) domain of B7-H3, a member of the B7 family of immune checkpoint molecules; The members here are composed of the immunoglobulin variable (IgV) domain of B7-H3 also known as CD276), a member of the B7 family of immune checkpoint molecules. B7-H3 is an important immune checkpoint member of the B7 family and shares homology with other B7 ligands such as programmed death ligand 1 (PD-L1). The B7 family molecules interact with CD28 on T-cells to provide co-stimulatory signals that regulate T-cell activation and T-helper cell differentiation. Although B7-H3 has been shown to have both co-stimulatory and co-inhibitory effects on T-cell responses, the most current studies describe B7-H3 as a T cell inhibitor that promotes tumor aggressiveness and proliferation. Moreover, B7-H3 is highly overexpressed on a wide range of human solid cancers and promotes tumor growth, metastasis, and drug resistance. Thus, B7-H3 expression in tumors often correlates with both negative prognosis and poor clinical outcome in cancer patients. B7-H3 protein contains a predicted signal peptide, V- and C-like Ig domains (IgV and IgC), a transmembrane region, and an intracellular tail.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 154091009  33 PTRHLLARVGGQAELSCQVIPPH--SVMHMEVRWFRSGHSQPVYLYRGGHKMSEEAAPEYANRTEFVKEAIGEGKVSLRI 110
Cdd:cd20934    3 PEDPVVALVGTDATLRCSFSPEPgfSLAQLSVFWQLTDTKQLVHSFTESQDQGRDQGSAYANRTALFPDLLAQGNASLRL 82

                         90       100       110
                 ....*....|....*....|....*....|..
gi 154091009 111 HNINILDDGPYQCSFNGSGFIDAAImNLNVTA 142
Cdd:cd20934   83 QRVRVADEGSYTCFVSVQDFGSAAV-SLQVAA 113

First immunoglobulin variable (IgV) domain of nectin-2, nectin-like protein 5, and similar domains; The members here are composed of the second immunoglobulin (Ig) domain of nectin-2 (also known as poliovirus receptor related protein 2 or Cluster of Differentiation 112 (CD112)), nectin-like protein 5 (CD155), and similar proteins. Nectins and Nectin-like molecules are a family of Ca(2+)-independent immunoglobulin-like transmembrane glycoproteins belonging to the class of adhesion receptors, consisting of nine members (nectins 1 through 4 and nectin-like proteins 1 through 5). Nectins are synaptic cell adhesion molecules (CAMs) which facilitate adhesion and signaling at various intracellular junctions. Nectins form homophilic cis-dimers, followed by homophilic and heterophilic trans-dimers involved in cell-cell adhesion. Nectin-2 and nectin-3 localize at Sertoli-spermatid junctions where they form heterophilic trans-interactions between the cells that are essential for the formation and maintenance of the junctions and for spermatid development. CD155 is the fifth member in the nectin-like molecule family, and functions as the receptor of poliovirus; therefore, CD155 is also referred to as Necl-5, or PVR. In contrast to all other family members, CD155 lacks self-adhesion capacity, yet it shares with nectins the feature to interact with other nectins. For instance, CD155 heterophilically trans-interacts with nectin-3, thereby contributing significantly to the establishment of adherens junctions between epithelial cells. This group belongs to the Constant 1 (C1)-set of IgSF domains, which has one beta-sheet that is formed by strands A-B-E-D and the other strands by G-F-C-C'.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 154091009  28 LRVTTPTrHLLARVGGQAELSCQVIPPHSVMHM-EVRWFRSGHSQPVYLYrggHKMSEEAAPEyANRTEFVKEAIGEG-- 104
Cdd:cd20989    1 VRVQVPP-EVRGFLGGSVTLPCHLLPPNMVTHVsQVTWQRHDEHGSVAVF---HPKQGPSFPE-SERLSFVAARLGAElr 75

                         90       100
                 ....*....|....*....|....*...
gi 154091009 105 KVSLRIHNINILDDGPYQCSF----NGS 128
Cdd:cd20989   76 NASLAMFGLRVEDEGNYTCEFatfpQGS 103

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 154091009  36 HLLARVGGQAELSCQVIPPH--SVMHMEVRWfRSGHSQPVY-LYRGGHKmSEEAAPEYANRTEFVKEaigegKVSLRIHN 112
Cdd:cd16087    2 KIQAYFNETAYLPCQFKNPQniSLSELVVFW-QDQKKLVLYeLYLGKEK-LDNVNSKYIGRTSFDQE-----NWTLQLHN 74

                         90
                 ....*....|.
gi 154091009 113 INILDDGPYQC 123
Cdd:cd16087   75 VQIKDQGTYQC 85

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 154091009    35 RHLLARVGGQAELSCQVIPPHSVmhmEVRWFRSGHSQPvyLYRGGHKMSEEaapeyanrtefvkeaigEGKVSLRIHNIN 114
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPP---EVTWYKQGGKLL--AESGRFSVSRS-----------------GSTSTLTISNVT 59

                           90       100
                   ....*....|....*....|....*.
gi 154091009   115 ILDDGPYQCSFNGSGFIDAAIMNLNV 140
Cdd:smart00410  60 PEDSGTYTCAATNSSGSASSGTTLTV 85

First immunoglobulin (Ig) variable (V) domain of rat MRC OX-2 antigen, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of rat MRC OX-2 antigen (also known as CD200) and similar proteins. MRC OX-2 is a membrane glycoprotein expressed in a variety of lymphoid and non-lymphoid cells in rats. It has a similar broad distribution pattern in humans. MRC OX-2 may regulate myeloid cell activity. The protein has an extracellular portion containing two Ig-like domains, a transmembrane portion, and a cytoplasmic portion.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 154091009  28 LRVTTPTRhllARVGGQAELSCQVIPPHSVMhmEVRWFRSGHSQPVYLYRGGHKMSEEAAPEYANRTEFvkEAIGEGKVS 107
Cdd:cd05846    2 VVHTGDTR---AVLGGNATLSCNLTLPEEVL--QVTWQKIKASSPENIVTYSKKYGVKIQPSYVRRISF--TSSGLNSTS 74

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 154091009 108 LRIHNINILDDGPYQCSFN--GSGFIDAAiMNLNV 140
Cdd:cd05846   75 ITIWNVTLEDEGCYKCLFNtfPDGIKSGT-ACLTV 108

First immunoglobulin variable (IgV) domain of DNAX accessory molecule 1, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of DNAX accessory molecule 1 (DNAM-1, also known as CD226). DNAM-1 is a transmembrane protein having two Ig-like domains. It is an adhesion molecule which plays a part in tumor-directed cytotoxicity and adhesion in natural killer (NK) cells and T lymphocytes. It has been shown to regulate the NK cell killing of several tumor types, including myeloma cells and ovarian carcinoma cells. DNAM-1 interacts specifically with poliovirus receptor (PVR; CD155) and nectin -2 (CD211), other members of the Ig superfamily. DNAM-1 is expressed in most peripheral T cells, NK cells, monocytes and a subset of B lymphocytes.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 154091009  61 EVRWFR-SGHSQPVYLYRGGHKMSEEaaPEYANRTEFVKEAIGEGKVSLRIHNINILDDGPYQCSF 125
Cdd:cd05889   31 QVEWTKiGGQKDNIAVYHPTHGMHIR--KPYAGRVYFLNSTMASNNMSLSFRNASEDDVGYYSCSL 94