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 1034561842  43 TVTTVASAGNIGEDGILSCTFEPDIKLSDIVIQWLKEGVLGLVHEFKEGKDELSEQDEMFRGRTAVFADQVIVGNASLRL 122
Cdd:cd20984     1 TVTAKHLAGNIGEDGILSCTFTPDIKLSDIVIQWLKEGDSGLVHEFKEGKDELSRQSPMFRGRTSLFADQVHVGNASLRL 80

                          90       100       110
                  ....*....|....*....|....*....|
gi 1034561842 123 KNVQLTDAGTYKCYIITSKGKGNANLEYKT 152
Cdd:cd20984    81 KNVQLTDAGTYLCIISNSKGTGNANMEYKT 110

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 1034561842  43 TVTTVASAGNIGEDGILSCTFEPDIKLSDIVIQWLKEGVLGLVHEFKEGKDELSEQDEMFRGRTAVFADQVIVGNASLRL 122
Cdd:cd20984     1 TVTAKHLAGNIGEDGILSCTFTPDIKLSDIVIQWLKEGDSGLVHEFKEGKDELSRQSPMFRGRTSLFADQVHVGNASLRL 80

                          90       100       110
                  ....*....|....*....|....*....|
gi 1034561842 123 KNVQLTDAGTYKCYIITSKGKGNANLEYKT 152
Cdd:cd20984    81 KNVQLTDAGTYLCIISNSKGTGNANMEYKT 110

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034561842   51 GNIGEDGILSCTFEPDiklSDIVIQWLKEGVLGLvhefkegkdelseqdeMFRGRTAVFADQvivGNASLRLKNVQLTDA 130
Cdd:smart00410   6 VKEGESVTLSCEASGS---PPPEVTWYKQGGKLL----------------AESGRFSVSRSG---STSTLTISNVTPEDS 63

                           90       100
                   ....*....|....*....|.
gi 1034561842  131 GTYKCYIITSKG--KGNANLE 149
Cdd:smart00410  64 GTYTCAATNSSGsaSSGTTLT 84

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 1034561842  43 TVTTVASAGNIGEDGILSCTFEPDIKLSDIVIQWLKEGVLGLVHEFKEGKDELSEQDEMFRGRTAVFADQVIVGNASLRL 122
Cdd:cd20984     1 TVTAKHLAGNIGEDGILSCTFTPDIKLSDIVIQWLKEGDSGLVHEFKEGKDELSRQSPMFRGRTSLFADQVHVGNASLRL 80

                          90       100       110
                  ....*....|....*....|....*....|
gi 1034561842 123 KNVQLTDAGTYKCYIITSKGKGNANLEYKT 152
Cdd:cd20984    81 KNVQLTDAGTYLCIISNSKGTGNANMEYKT 110

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 1034561842  53 IGEDGILSCTF--EPDIKLSDIVIQWLKEGVLGLVHEFKEGKDELSEQDEMFRGRTAVFADQVIVGNASLRLKNVQLTDA 130
Cdd:cd20934    11 VGTDATLRCSFspEPGFSLAQLSVFWQLTDTKQLVHSFTESQDQGRDQGSAYANRTALFPDLLAQGNASLRLQRVRVADE 90

                  ....*..
gi 1034561842 131 GTYKCYI 137
Cdd:cd20934    91 GSYTCFV 97

Immunoglobulin Variable (IgV) domain of Programmed death ligand 1 (PD-L1); The members here are composed of the immunoglobulin variable (IgV) domain of Programmed death ligand 1 (PD-L1; also known as Cluster of Differentiation 274 (CD274)). PD-L1 is a cell-surface ligand that competes with PD-L2 for binding to the immunosuppressive receptor programmed death-1 (PD-1). PD-1 is a member of the B7 family that plays an important role in negatively regulating immune responses upon interaction with its two ligands, PD-L1 or PD-L2. Like PD-L2, PD-L1 interacts with PD-1 and suppresses T cell proliferation and cytokine production. The PD-1 receptor is expressed on the surface of activated T cells, while PD-L1 is expressed on cancer cells. When PD-1 and PD-L1 bind together, they form a molecular shield protecting tumor cells from being destroyed by the immune system. Thus, inhibiting the binding of PD-L1 to PD-1 with an antibody leads to killing of tumor cells by T cells. PD-1 inhibitors (such as Pembrolizumab, Nivolumab, and Cemiplimab) and PD-L1 inhibitors (such as Atezolizumab, Avelumab, and Durvalumab ) are an emerging class of immunotherapy that stimulate lymphocytes against tumor cells.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034561842  42 ITVTTVASAGNIGEDGILSCTF--EPDIKLSDIVIQWLKEGvlGLVHEFKEGKDELSEQDEMFRGRTAVFADQVIVGNAS 119
Cdd:cd20947     1 VTVPKDLYVVEYGSNMTIECKFpvEKQLDLAALIVYWEMED--KNIIQFVHGEEDLKVQHSSYRQRARLLKDQLSLGNAA 78

                          90
                  ....*....|....*...
gi 1034561842 120 LRLKNVQLTDAGTYKCYI 137
Cdd:cd20947    79 LQITDVKLQDAGVYRCMI 96

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 1034561842  54 GEDGILSCTFEPDIKLSDIVIQWLKEGVLG----LVHEFKEGKDElseqdEMFRGRTAVFADqVIVGNASLRLKNVQLTD 129
Cdd:pfam07686  11 GGSVTLPCTYSSSMSEASTSVYWYRQPPGKgptfLIAYYSNGSEE-----GVKKGRFSGRGD-PSNGDGSLTIQNLTLSD 84

                          90
                  ....*....|.
gi 1034561842 130 AGTYKCYIITS 140
Cdd:pfam07686  85 SGTYTCAVIPS 95

Immunoglobulin variable (IgV) domain of B7-H6; The members here are composed of the immunoglobulin variable (IgV) domain of B7-H6 (also known as NCR3LG1). B7-H6 contains one IgV domain and one IgC domain (IgV-IgC) and belongs to the B7-family, which consists of structurally related cell-surface protein ligands which bind to receptors on lymphocytes that regulate immune responses. B7-H6 is a ligand of NKp30, which is a member of CD28 family and an activating receptor of natural killer (NK) cells. The expression of NKp30 has been found in most of NK cells, which is involved in the process of tumor cell killing and interaction with antigen presenting cells (APCs) such as dendritic cells. Studies showed that NK cells eliminate B7-H6-expressing tumor cells either directly via cytotoxicity or indirectly by cytokine secretion. For instance, chimeric NKp30-expressing T cells responded to B7-H6(+) tumor cells and those T cells produced IFN-gamma and killed B7-H6-expressing tumor cells in vivo. B7-H6 mRNA is not found in normal cells, while high expression of B7-H6 is found in certain type tumor cells, such as lymphoma, leukemia, ovarian cancer, brain tumors, breast cancers, and various sarcomas. Since B7-H6 can bind NKp30 to exert anti-tumor effects by NK cells, which are able to recognize the difference between cancer cells and normal cells, B7-H6 may serve as a promising target for cancer immunotherapy.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1034561842  97 EQDEMFRGRTAVFADQVIVGNASLRLKNVQLTDAGTYKCYIITS--KGKGNANLE 149
Cdd:cd20981    59 DHQKAFRPGAIVSPWRLKSGDASLQLPGVQLEEAGEYRCEVVVTplKAQGTVQLE 113

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034561842   51 GNIGEDGILSCTFEPDiklSDIVIQWLKEGVLGLvhefkegkdelseqdeMFRGRTAVFADQvivGNASLRLKNVQLTDA 130
Cdd:smart00410   6 VKEGESVTLSCEASGS---PPPEVTWYKQGGKLL----------------AESGRFSVSRSG---STSTLTISNVTPEDS 63

                           90       100
                   ....*....|....*....|.
gi 1034561842  131 GTYKCYIITSKG--KGNANLE 149
Cdd:smart00410  64 GTYTCAATNSSGsaSSGTTLT 84

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 1034561842  59 LSCTFEPDiklSDIVIQWLKEGVlglvhefkegkdELSEQDEMFRgrtavfadQVIVGNASLRLKNVQLTDAGTYKCYII 138
Cdd:cd00096     3 LTCSASGN---PPPTITWYKNGK------------PLPPSSRDSR--------RSELGNGTLTISNVTLEDSGTYTCVAS 59

                  ....
gi 1034561842 139 TSKG 142
Cdd:cd00096    60 NSAG 63

Fifth Ig-like domain of Roundabout (Robo) homolog 1/2, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fifth Ig-like domain of Roundabout (Robo) homolog 1/2 and similar domains. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, -2, and -3), and three mammalian Slit homologs (Slit-1,-2, -3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, -2, and -3 are expressed by commissural neurons in the vertebrate spinal cord and Slits 1, -2, -3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of slit responsiveness, antagonizes slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. The fifth Ig-like domain of Robo 1 and 2 is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1034561842  73 VIQWLKEGVLGLVhefkegkdelseQDEMFRgrtavfadqvIVGNASLRLKNVQLTDAGTYKCYIITSKGK 143
Cdd:cd20952    30 TISWLKDGVPLLG------------KDERIT----------TLENGSLQIKGAEKSDTGEYTCVALNLSGE 78

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1034561842  41 SITVTTVASAGNIGEDGILSCTFEPDiklSDIVIQWLKEGVLglvhefkegKDELSEQDEMFRGrtavfadqvivGNASL 120
Cdd:pfam13927   3 VITVSPSSVTVREGETVTLTCEATGS---PPPTITWYKNGEP---------ISSGSTRSRSLSG-----------SNSTL 59

                          90
                  ....*....|....*
gi 1034561842 121 RLKNVQLTDAGTYKC 135
Cdd:pfam13927  60 TISNVTRSDAGTYTC 74

Third immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, Robo3), and three mammalian Slit homologs (Slit-1,Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, and Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30
                  ....*....|....*....|....*....|....*....
gi 1034561842  97 EQDEMFRGRTAVFADQvivgnaSLRLKNVQLTDAGTYKC 135
Cdd:cd05725    34 EDGELPKGRYEILDDH------SLKIRKVTAGDMGSYTC 66