Signal-regulatory protein (SIRP) immunoglobulin-like domain 3; 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 3 (C1 repeat 2). 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 that 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        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 251 VPPFLEVTQQSMRADNQVNVTCQVTKFYPQRLQLTWLENGNVSRTEMASALPENKDGTYNWTSWLLVNVSAHRDDVKLTC 330
Cdd:cd16085     1 VPPTLEVTQQPTMVWNQVNVTCQVEKFYPQRLQLTWLENGNVSRTETPSTLTVNKDGTYNWTSWLLVNVSAHREDVVLTC 80

                          90
                  ....*....|....*.
gi 1622839945 331 QVEHDGQPAVNKSFSV 346
Cdd:cd16085    81 QVEHDGQPAVTKNHTL 96

Signal-regulatory protein (SIRP) immunoglobulin-like domain 3; 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 3 (C1 repeat 2). 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 that 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        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 251 VPPFLEVTQQSMRADNQVNVTCQVTKFYPQRLQLTWLENGNVSRTEMASALPENKDGTYNWTSWLLVNVSAHRDDVKLTC 330
Cdd:cd16085     1 VPPTLEVTQQPTMVWNQVNVTCQVEKFYPQRLQLTWLENGNVSRTETPSTLTVNKDGTYNWTSWLLVNVSAHREDVVLTC 80

                          90
                  ....*....|....*.
gi 1622839945 331 QVEHDGQPAVNKSFSV 346
Cdd:cd16085    81 QVEHDGQPAVTKNHTL 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 1622839945  38 QPEKSVSVAAGDSATLNCTVTSLI--PVGPIQWFRG--AGPGRELIYHQKEGHFPRVTS--VSESTKRNNMDFSIHISNI 111
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSSMseASTSVYWYRQppGKGPTFLIAYYSNGSEEGVKKgrFSGRGDPSNGDGSLTIQNL 80

                          90       100       110
                  ....*....|....*....|....*....|...
gi 1622839945 112 TPADAGTYYCVKFrkgsPDVEVKSGAGTELSVR 144
Cdd:pfam07686  81 TLSDSGTYTCAVI----PSGEGVFGKGTRLTVL 109

Immunoglobulin C1-set domain;

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1622839945 163 HTVSFTCESHGFSPRDITLKWFKNGNELSDFQTNVDP-AGKSVSYSIRSTARVVLSRRDVHSQVICEVAHVTL 234
Cdd:pfam07654  13 KPNTLTCLVTGFYPPDITVTWLKNGQEVTEGVKTTPPsPNSDWTYQLSSYLTVTPSDWESGDEYTCRVEHEGL 85

Immunoglobulin C-Type;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1622839945  164 TVSFTCESHGFSPRDITLKWFKNGNELSDFQTNVDPAGKS-VSYSIRSTARVVLSRRDVHSQVICEVAHVTLQG 236
Cdd:smart00407   1 KATLVCLVSGFYPPDITVTWLRNGQEVTEGVSTTDPLKNSdGTYFLSSYLTVPASTWESGDVYTCQVTHEGLKE 74

envelope glycoprotein C; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  66 IQWFRGAGPGRELIYHQKEGHFPRVTSVsestkrnnmdfsihISNITPADAGTYYCVkfrKGSPDVEVKSGAGTELSVRA 145
Cdd:PHA03270  158 VRWAEGAGPGARPRLYSVEGTFPTQRLV--------------IQELTLATQGMYYWA---RGPADRPHRYGTWTRVRMFR 220

                          90       100       110       120       130       140       150
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1622839945 146 KPSA-----PVVSGPAVRAtaehtvsfTCESHGFSPRD-ITLKWFKNGNELSD---FQTNVD--PAGKSVSYSIRSTAR 213
Cdd:PHA03270  221 RPSLsirphAVLEGEPFGA--------TCVAANYYPGDrAAFRWFEGGDEVFAperVRTRVDaqRDGFSATSTLTSEAR 291

Signal-regulatory protein (SIRP) immunoglobulin-like domain 3; 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 3 (C1 repeat 2). 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 that 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        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 251 VPPFLEVTQQSMRADNQVNVTCQVTKFYPQRLQLTWLENGNVSRTEMASALPENKDGTYNWTSWLLVNVSAHRDDVKLTC 330
Cdd:cd16085     1 VPPTLEVTQQPTMVWNQVNVTCQVEKFYPQRLQLTWLENGNVSRTETPSTLTVNKDGTYNWTSWLLVNVSAHREDVVLTC 80

                          90
                  ....*....|....*.
gi 1622839945 331 QVEHDGQPAVNKSFSV 346
Cdd:cd16085    81 QVEHDGQPAVTKNHTL 96

Immunoglobulin variable domain (IgV); The members here are composed of the immunoglobulin variable domain (IgV). The IgV family contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology, and 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. 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" strands in the other.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  36 VIQPEKSVSVAAGDSATLNCTVTSLIPVGPIQWFRGA-GPGRELIYHQ-------KEGHFPRVTSVSESTKrnnmDFSIH 107
Cdd:cd00099     1 VTQSPRSLSVQEGESVTLSCEVSSSFSSTYIYWYRQKpGQGPEFLIYLssskgktKGGVPGRFSGSRDGTS----SFSLT 76

                          90       100       110
                  ....*....|....*....|....*....|....*.
gi 1622839945 108 ISNITPADAGTYYCVKFRKGSPDvEVKSGAGTELSV 143
Cdd:cd00099    77 ISNLQPEDSGTYYCAVSESGGTD-KLTFGSGTRLTV 111

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 1622839945  38 QPEKSVSVAAGDSATLNCTVTSLI--PVGPIQWFRG--AGPGRELIYHQKEGHFPRVTS--VSESTKRNNMDFSIHISNI 111
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSSMseASTSVYWYRQppGKGPTFLIAYYSNGSEEGVKKgrFSGRGDPSNGDGSLTIQNL 80

                          90       100       110
                  ....*....|....*....|....*....|...
gi 1622839945 112 TPADAGTYYCVKFrkgsPDVEVKSGAGTELSVR 144
Cdd:pfam07686  81 TLSDSGTYTCAVI----PSGEGVFGKGTRLTVL 109

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) alpha chain and similar proteins; The members here are composed of the immunoglobulin (Ig) variable domain of the alpha chain of alpha/beta T-cell antigen receptors (TCRs). TCRs mediate antigen recognition by T lymphocytes, and are composed of alpha and beta, or gamma and delta polypeptide chains with variable (V) and constant (C) regions. This group represents the variable domain of the alpha chain of TCRs and also includes the variable domain of delta chains of TCRs. Alpha/beta TCRs recognize antigen as peptide fragments presented by major histocompatibility complex (MHC) molecules. The variable domain of TCRs is responsible for antigen recognition, and is located at the N-terminus of the receptor. Gamma/delta TCRs recognize intact protein antigens directly without antigen processing and recognize MHC independently of the bound peptide. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  36 VIQPEKSVSVAAGDSATLNCTVTSlIPVGPIQWFRgAGPGRELIY---------HQKEGHFprvtSVSESTKRNnmDFSI 106
Cdd:cd04983     1 VTQSPQSLSVQEGENVTLNCNYST-STFYYLFWYR-QYPGQGPQFliyissdsgNKKKGRF----SATLDKSRK--SSSL 72

                          90       100       110
                  ....*....|....*....|....*....|....*...
gi 1622839945 107 HISNITPADAGTYYCVkFRKGSPDVEVKSGAGTELSVR 144
Cdd:cd04983    73 HISAAQLSDSAVYFCA-LSESGGTGKLTFGKGTRLTVE 109

Immunoglobulin domain of Cluster of Differentiation (CD) 1; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin domain of Cluster of Differentiation (CD) 1. CD1 family of transmembrane glycoproteins, are structurally related to the major histocompatibility complex (MHC) proteins and form heterodimers with beta-2-microglobulin. They mediate the presentation of primarily lipid and glycolipid antigens of self or microbial origin to T cells. The human genome contains five CD1 family genes (CD1a, CD1b, CD1c, CD1d, and CD1e) organized in a cluster on chromosome 1. The CD1 family members are thought to differ in their cellular localization and specificity for particular lipid ligands. CD1a localizes to the plasma membrane and to recycling vesicles of the early endocytic system. Alternative splicing results in multiple transcript variants. Immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class I alpha chain. Class I MHC proteins bind antigenic peptide fragments and present them to CD8+ T lymphocytes. Class I molecules consist of a transmembrane alpha chain and a small chain called the beta-2-microglobulin. The alpha chain contains three extracellular domains, two of which fold together to form the peptide-binding cleft (alpha1 and alpha2), and one which has an Ig fold (alpha3). Peptide binding to class I molecules occurs in the endoplasmic reticulum (ER) and involves both chaperones and dedicated factors to assist in peptide loading. Class I MHC molecules are expressed on most nucleated cells. C1-set Ig domains have one beta sheet that is formed by strands A, B, E, and D and the other strands by G, F, C, and C'.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 251 VPPFLEVTQQSMRADNQVNVTCQVTKFYPQRLQLTWLENGNVSRTEMASA--LPeNKDGTYNWTSWLLVNVSahrDDVKL 328
Cdd:cd21029     1 VKPRVRLSSRPSPGDGHLQLSCHVTGFYPRPIEVTWLRDGQEQMDGTQSGgiLP-NHDGTYQLRKTLDIAPG---EGAGY 76

                  ....*...
gi 1622839945 329 TCQVEHDG 336
Cdd:cd21029    77 SCRVDHSS 84

Immunoglobulin (Ig) light chain, kappa type, variable (V) domain; The members here are composed of the immunoglobulin (Ig) light chain, kappa type, variable (V) domain. This group contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains (alpha, gamma, delta, epsilon, and mu), which determines the type of immunoglobulin formed: IgA, IgG, IgD, IgE, and IgM, respectively. In higher vertebrates, there are two types of light chain, designated kappa and lambda, which seem to be functionally identical, and can associate with any of the heavy chains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  34 LQVIQPEKSVSVAAGDSATLNCTVTSLIPVGPIQWfrgagpgreliYHQKEGHFPRVTSVSESTKRNNM----------- 102
Cdd:cd04980     1 IVMTQSPASLSVSPGERVTISCKASQSISSNYLAW-----------YQQKPGQAPKLLIYYASTLHSGVpsrfsgsgsgt 69

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|.
gi 1622839945 103 DFSIHISNITPADAGTYYCVKFRKGSPDVevksGAGTELSV 143
Cdd:cd04980    70 DFTLTISSVEPEDAAVYYCQQGYTFPYTF----GGGTKLEI 106

Immunoglobulin C-Type;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1622839945  267 QVNVTCQVTKFYPQRLQLTWLENG-----NVSRTEMAsalpENKDGTYNWTSWLLVNVSAHRDDVKLTCQVEHDG 336
Cdd:smart00407   1 KATLVCLVSGFYPPDITVTWLRNGqevteGVSTTDPL----KNSDGTYFLSSYLTVPASTWESGDVYTCQVTHEG 71

CH2 domain (second constant Ig domain of the heavy chain) in immunoglobulin mu chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin constant domain (IgC) of mu heavy chains. This domain is found on the Fc fragment. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda; each is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1622839945 160 TAEHTVSFTCESHGFSPRDITLKWFKNGNELSDFQTNVDPAGKS---VSYSIRSTARVVLSRRDVHSQVICEVAH 231
Cdd:cd16093    15 LGNRTATFVCLATGFSPKTISFKWLRNGKEVTSSTGAVVEEPKEdgkTLYSATSFLTITESEWKSQTEFTCEFKH 89

Immunoglobulin domain of Zn-alpha2-glycoprotein (ZAG); member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin domain of Zn-alpha2-glycoprotein (ZAG). ZAG is a soluble protein that is present in serum and other body fluids. ZAG stimulates lipid degradation in adipocytes and causes the extensive fat losses associated with some advanced cancers. The 2.8 angstrom crystal structure of ZAG resembles a class I major histocompatibility complex (MHC) heavy chain, but ZAG does not bind the class I light chain beta-2-microglobulin. The ZAG structure includes a large groove analogous to class I MHC peptide binding grooves. Instead of a peptide, the ZAG groove contains a nonpeptidic compound that may be implicated in lipid catabolism under normal or pathological conditions. IgC_MHC_I_alpha3; Immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class I alpha chain. Class I MHC proteins bind antigenic peptide fragments and present them to CD8+ T lymphocytes. Class I molecules consist of a transmembrane alpha chain and a small chain called the beta-2-microglobulin. The alpha chain contains three extracellular domains, two of which fold together to form the peptide-binding cleft (alpha1 and alpha2), and one which has an Ig fold (alpha3). Peptide binding to class I molecules occurs in the endoplasmic reticulum (ER) and involves both chaperones and dedicated factors to assist in peptide loading. Class I MHC molecules are expressed on most nucleated cells.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 252 PPFLEVTQQSMRADNQVnVTCQVTKFYPQRLQLTWLENGNVSRTEMASALPENKDGTYNwtSWLLVNVSAHrDDVKLTCQ 331
Cdd:cd21010     4 PPSVSVTSHVAPGKNRT-LKCLAYDFYPRGISLHWTRAGKVQESESGGDVLPSGNGTYQ--SWVVVEVPPQ-DRAPYSCH 79

                  ....*....
gi 1622839945 332 VEHDG--QP 338
Cdd:cd21010    80 VEHSSlaQP 88

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945   50 SATLNCTV-TSLIPVGPIQWFRgAGPGREL---IYHQKEGHF-------PRVTSVSESTKRnnmDFSIHISNITPADAGT 118
Cdd:smart00406   1 SVTLSCKFsGSTFSSYYVSWVR-QPPGKGLewlGYIGSNGSSyyqesykGRFTISKDTSKN---DVSLTISNLRVEDTGT 76

                   ...
gi 1622839945  119 YYC 121
Cdd:smart00406  77 YYC 79

Class Ia major histocompatibility complex (MHC) immunoglobulin domain of MIC-A and MIC-B; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class Ia major histocompatibility complex (MHC) immunoglobulin domain of MIC-A and MIC-B. MIC-A and MIC-B are homologs that serve as stress-inducible antigens on epithelial and epithelially derived cells. Both serve as ligands for the widely expressed activating immunoreceptor NKG2D, a C-type lectin-like activating immunoreceptor. MIC-B is very similar in structure to MIC-A and likely interacts with NKG2D in an analogous manner. The interdomain flexibility observed in the MIC-A structures, a feature unique to MIC proteins among MHC class I proteins and homologs, is also displayed by MIC-B, with an interdomain relationship intermediate between the two examples of MIC-A structures. Mapping sequence variations onto the structures of MIC-A and MIC-B reveals patterns completely distinct from those displayed by classical MHC class I proteins, with a number of substitutions falling on positions likely to affect interactions with NKG2D, but with other positions lying distant from the NKG2D binding sites or buried within the core of the proteins. Members of the IgC 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 1622839945 251 VPPFLEVTQQSMRADNqVNVTCQVTKFYPQRLQLTWLENG---NVSRTEMASALPenkDGTYNWTSWLLVNVSaHRDDVK 327
Cdd:cd21017     3 VPPMVNVTRSEASEGN-ITVTCRASGFYPWNITLSWRQDGvslSHDTQQWGDVLP---DGNGTYQTWVATRIC-QGEEQR 77

                  ....*....
gi 1622839945 328 LTCQVEHDG 336
Cdd:cd21017    78 FTCYMEHSG 86

Second immunoglobulin (Ig)-like domain of the nectin-like molecules Necl-1 - Necl-4; member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin (Ig)-like domain of the nectin-like molecules Necl-1 (also known as cell adhesion molecule 3 or CADM3), Necl-2 (also known as CADM1), Necl-3 (also known as CADM2) and Necl-4 (also known as CADM4). 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. 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. Necl-4 is expressed on Schwann cells, and plays a key part in initiating peripheral nervous system (PNS) myelination. Necl-4 participates in cell-cell adhesion and is proposed to play a role in tumor suppression.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 147 PSAPVVSGPAVRATAEHTVSFTCESHGFSPRdITLKWFKNGNELSDFQT-NVDPAGKSvsYSIRSTARVVLSRRDVHSQV 225
Cdd:cd05761     4 PEKPVITGFTSPVVEGDEITLTCTTSGSKPA-ADIRWFKNDKELKGVKEvQESGAGKT--FTVTSTLRFRVDRDDDGVAV 80

                          90
                  ....*....|....*
gi 1622839945 226 ICEVAHVTLQGDPLR 240
Cdd:cd05761    81 ICRVDHESLTSTPKQ 95

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  35 QVIQPEKSVSVAAGDSATLNCTVTSlIPVGPIQWFRGagpGRELIyhqkeghfprvTSVSESTKRNNMDFSIHISNITPA 114
Cdd:pfam13927   3 VITVSPSSVTVREGETVTLTCEATG-SPPPTITWYKN---GEPIS-----------SGSTRSRSLSGSNSTLTISNVTRS 67

                  ....*...
gi 1622839945 115 DAGTYYCV 122
Cdd:pfam13927  68 DAGTYTCV 75

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) beta chain; The members here are composed of the immunoglobulin (Ig) variable domain of the beta chain of alpha/beta T-cell antigen receptors (TCRs). TCRs mediate antigen recognition by T lymphocytes, and are composed of alpha and beta, or gamma and delta, polypeptide chains with variable (V) and constant (C) regions. This group includes the variable domain of the alpha chain of alpha/beta TCRs. Alpha/beta TCRs recognize antigen as peptide fragments presented by major histocompatibility complex (MHC) molecules. The variable domain of TCRs is responsible for antigen recognition, and is located at the N-terminus of the receptor. Gamma/delta TCRs recognize intact protein antigens directly without antigen processing and recognize MHC independently of the bound peptide. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  36 VIQPEKSVSVAAGDSATLNCTVTSLIPVgpIQWFRGAgPGREL---IYHQKEGHfPRVTSVSES----TKRNNMDFSIHI 108
Cdd:cd05899     1 VTQSPRYLIKRRGQSVTLRCSQKSGHDN--MYWYRQD-PGKGLqllFYSYGGGL-NEEGDLPGDrfsaSRPSLTRSSLTI 76

                          90       100       110
                  ....*....|....*....|....*....|....*
gi 1622839945 109 SNITPADAGTYYCVKFRKGSPDvEVKSGAGTELSV 143
Cdd:cd05899    77 KSAEPEDSAVYLCASSLGGGAD-EAYFGPGTRLTV 110

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DM; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DM. Human HLA-DM plays a critical role in antigen presentation to CD4 T cells by catalyzing the exchange of peptides bound to MHC class II molecules. Type 1 diabetes is correlated with DM activation and it is also implicated in viral infections such as herpes simplex virus, celiac disease, multiple sclerosis, other autoimmune diseases, and leukemia. MHC class II molecules play a key role in the initiation of the antigen-specific immune reponse. These molecules have been shown to be expressed constitutively on the cell surface of professional antigen-presenting cells (APCs), including B-lymphocytes, monocytes, and macrophages in both humans and mice. The expression of these molecules has been shown to be induced in nonprofessional APCs such as keratinocyctes, and they are expressed on the surface of activated human T cells and on T cells from other species. The MHC II molecules present antigenic peptides to CD4(+) T-lymphocytes. These peptides derive mostly from proteolytic processing via the endocytic pathway, of antigens internalized by the APC. These peptides bind to the MHC class II molecules in the endosome before they are transported to the cell surface. MHC class II molecules are heterodimers, comprised of two similarly-sized membrane-spanning chains, alpha and beta. Each chain had two globular domains (N- and C-terminal), and a membrane-anchoring transmembrane segment. The two chains form a compact four-domain structure. The peptide-binding site is a cleft in the structure.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 250 RVPPFLEV---TQQSMRAdnQVNVTCQVTKFYPQRLQLTWLENGNV---SRTEMASALPeNKDGTYNWTSWLLVNVSAhr 323
Cdd:cd21002     1 RRPPSVRVaptTPFNTRE--PVMLACHVWGFYPADVTITWLKNGDPvapHSSAPKTAQP-NGDWTYQTQVTLAVTPSP-- 75

                          90
                  ....*....|....*
gi 1622839945 324 DDVkLTCQVEHDGQP 338
Cdd:cd21002    76 GDT-YTCSVQHASLP 89

Class Ia major histocompatibility complex (MHC) immunoglobulin domain of H2-Dd; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class Ia major histocompatibility complex (MHC) immunoglobulin domain of H2-Dd. Mouse MHC is composed of 11 subclasses. It includes the classical MHC class I (MHC-Ia) that comprises H-2D, H-2K and H-2L subclasses, the non-classical MHC class I (MHCIb) that comprises H-2Q, H-2M and H-2T subclasses, the classical MHC class II (MHC-IIa) that includes H-2A(I-A) and H-2E(I-E) subclasses, and the non-classical MHC class II (MHC-IIb) comprises H-2M and H-2O. H-2K, H-2D, and H-2L are 80 to 90% homologous at the amino acid level yet appear to be involved in different recognition reactions and are differentially expressed on lymphoid cells. Class I MHC proteins bind antigenic peptide fragments and present them to CD8+ T lymphocytes. Class I molecules consist of a transmembrane alpha chain and a small chain called the beta-2-microglobulin. The alpha chain contains three extracellular domains, two of which fold together to form the peptide-binding cleft (alpha1 and alpha2), and one which has an Ig fold (alpha3). Peptide binding to class I molecules occurs in the endoplasmic reticulum (ER) and involves both chaperones and dedicated factors to assist in peptide loading. Class I MHC molecules are expressed on most nucleated cells.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 252 PPFLEVTQQSmRADNQVNVTCQVTKFYPQRLQLTWLENGN--VSRTEMASALPENkDGTYNwtSWLLVNVSAHRDDvKLT 329
Cdd:cd21020     5 PPKAHVTHHR-RPEGDVTLRCWALGFYPADITLTWQLNGEelTQEMELVETRPAG-DGTFQ--KWASVVVPLGKEQ-KYT 79

                  ....*....
gi 1622839945 330 CQVEHDGQP 338
Cdd:cd21020    80 CHVEHEGLP 88

Immunoglobulin domain of Cluster of Differentiation (CD) 1; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin domain of Cluster of Differentiation (CD) 1. CD1 family of transmembrane glycoproteins, are structurally related to the major histocompatibility complex (MHC) proteins and form heterodimers with beta-2-microglobulin. They mediate the presentation of primarily lipid and glycolipid antigens of self or microbial origin to T cells. The human genome contains five CD1 family genes (CD1a, CD1b, CD1c, CD1d, and CD1e) organized in a cluster on chromosome 1. The CD1 family members are thought to differ in their cellular localization and specificity for particular lipid ligands. CD1a localizes to the plasma membrane and to recycling vesicles of the early endocytic system. Alternative splicing results in multiple transcript variants. Immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class I alpha chain. Class I MHC proteins bind antigenic peptide fragments and present them to CD8+ T lymphocytes. Class I molecules consist of a transmembrane alpha chain and a small chain called the beta-2-microglobulin. The alpha chain contains three extracellular domains, two of which fold together to form the peptide-binding cleft (alpha1 and alpha2), and one which has an Ig fold (alpha3). Peptide binding to class I molecules occurs in the endoplasmic reticulum (ER) and involves both chaperones and dedicated factors to assist in peptide loading. Class I MHC molecules are expressed on most nucleated cells. C1-set Ig domains have one beta sheet that is formed by strands A, B, E, and D and the other strands by G, F, C, and C'.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 148 SAPVVSGPAVRATAEHTVSFTCESHGFSPRDITLKWFKNGNELSD--FQTNVDPAGKSvSYSIRSTARVVLSRRDVHSqv 225
Cdd:cd21029     1 VKPRVRLSSRPSPGDGHLQLSCHVTGFYPRPIEVTWLRDGQEQMDgtQSGGILPNHDG-TYQLRKTLDIAPGEGAGYS-- 77

                          90
                  ....*....|..
gi 1622839945 226 iCEVAHVTLQGD 237
Cdd:cd21029    78 -CRVDHSSLKQD 88

CH3 domain (third constant Ig domain of the heavy chain) in immunoglobulin heavy alpha, gamma, and delta chains, and CH4 domain (fourth constant Ig domain of the heavy chain) in immunoglobulin heavy alpha, epsilon, and mu chains; member of the C1-set of I; The members here are composed of the third and fourth immunoglobulin constant domain (IgC) of alpha, delta, gamma and alpha, epsilon, and mu heavy chains, respectively. This domain is found on the Fc fragment. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda; each is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 147 PSAPVVSGPAVRATAEHTVSFTCESHGFSPRDITLKWFKNGNELSD---FQTNVDPAGKSvSYSIRSTARVVLSRRDVHS 223
Cdd:cd05768     1 PSVYLLPPPEEELSLNETVTLTCLVKGFYPEDIFVSWLQNGEPLPSadyKTTAPVPESDG-SFFVYSKLNVSTADWNSGD 79

                          90
                  ....*....|....*..
gi 1622839945 224 QVICEVAHvtlQGDPLR 240
Cdd:cd05768    80 VFSCVVGH---EALPLQ 93

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DQ and I-A; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of human histocompatibility antigen (HLA) DQ and mouse I-A. Three genetically distinct isotypes of class II MHC molecules are found in humans (HLA-DR, HLA-DQ, and HLA-DP), and two in mice (I-E and I-A). I-A and I-E have the same basic features insofar as peptide loading and presentation, they differ in that each interacts with distinctly different sets of peptides, and in the incidence of deletion of their genes. A structural understanding of the similarities and differences between I-A and I-E may help with understanding their roles in peptide presentation and T cell activation. Mouse I-Ag7 has a genetic susceptibility to autoimmune diabetes due to its small, uncharged amino acid residue at position 57 of their beta chain which results in the absence of a salt bridge between beta 57 and Arg alpha 76, which is adjacent to the P9 pocket of the peptide-binding groove. Human HLA-DR, -DQ, and -DP are about 70% similar to each other. HLA-DQ (DQ) is a cell surface receptor protein found on antigen presenting cells. It is an alphabeta heterodimer of type MHC class II. The alpha and beta chains are encoded by two loci, HLA-DQA1 and HLA-DQB1, that are adjacent to each other on chromosome band 6p21.3. A person often produces two alpha-chain and two beta chain variants and thus 4 isoforms of DQ. HLA-DQ is involved in the autoimmune diseases celiac disease and diabetes mellitus type. DQ is one of several antigens involved in rejection of organ transplants. DQ2 is encoded by the HLA-DQB1*02 allele group. DQ6 is encoded by the HLA-DQB1*06 allele group. DQ2 beta-chains combine with alpha-chains, encoded by genetically linked HLA-DQA1 alleles, to form the cis-haplotype isoforms. These isoforms, nicknamed DQ2.2 and DQ2.5, are also encoded by the DQA1*0201 and DQA1*0501 genes, respectively. DQ6 beta-chains combine with alpha-chains, encoded by genetically linked HLA-DQA1 alleles, to form the cis-haplotype isoforms. For DQ6, however, cis-isoform pairing only occurs with DQ1 alpha-chains. There are many haplotypes of DQ6. Susceptibility to Leptospirosis infection was found associated with undifferentiated DQ6. DQ8 is determined by the antibody recognition of beta8 and this generally detects the gene product of DQB1*0302. DQ8 is commonly linked to autoimmune disease in the human population. DQ8 is the second most predominant isoform linked to celiac disease and the DQ most linked to Type 1 diabetes. DQ8 increases the risk for rheumatoid arthritis and is linked to the primary risk locus for RA, HLA-DR4. DR4 also plays an important role in Type 1 diabetes. DQ8 is a split antigen of the DQ3 broad antigen. MHC class II molecules play a key role in the initiation of the antigen-specific immune response. They are expressed constitutively on the cell surface of professional antigen-presenting cells (APCs), including B-lymphocytes, monocytes, and macrophages in both humans and mice, and induced in nonprofessional APCs, such as keratinocyctes; they are expressed on the surface of activated human T cells and on T cells from other species. MHC II molecules present antigenic peptides to CD4(+) T-lymphocytes; these peptides derive mostly from proteolytic processing via the endocytic pathway, of antigens internalized by the APC, and bind to the MHC class II molecules in the endosome before they are transported to the cell surface. MHC class II molecules are heterodimers, comprised of two similarly-sized membrane-spanning chains, alpha and beta. Each chain had two globular domains (N- and C-terminal), and a membrane-anchoring transmembrane segment. The two chains form a compact four-domain structure. The peptide-binding site is a cleft in the structure.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 250 RVPPFLEVTQQSMRADNQVN-VTCQVTKFYPQRLQLTWLENGNVSRTEMASA-LPENKDgtynWTSWLLV--NVSAHRDD 325
Cdd:cd21001     1 RVEPTVTISPSRTEALNHHNlLVCSVTDFYPGQIKVRWFRNDQEETAGVVSTpLIRNGD----WTFQILVmlEMTPQRGD 76

                  ....*....
gi 1622839945 326 VkLTCQVEH 334
Cdd:cd21001    77 V-YTCHVEH 84

Class Ib major histocompatibility complex (MHC) immunoglobulin domain of Qa-1b; member of the C1-set of Ig superfamily (IgSF) domains; The non-classical mouse MHC class I (MHC-I) molecule Qa-1b is a non-polymorphic MHC molecule with an important function in innate immunity. It binds and presents signal peptides of classical MHC-I molecules at the cell surface and, as such, act as an indirect sensor for the normal expression of MHC-I molecules. This signal peptide dominantly accommodated in the groove of Qa-1b is called Qdm, for Qa-1 determinant modifier, and its amino acid sequence AMAPRTLLL is highly conserved among mammalian species. The Qdm/Qa-1b complex serves as a ligand for the germ-line encoded heterodimeric CD94/NKG2A receptors expressed on natural killer (NK) cells and activated CD8+ T cells and transduces inhibitory signals to these lymphocytes. Thus, upon binding, Qa-1b signals NK cells not to engage in cell lysis. The molecular basis of Qa-1b function is unclear.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 252 PPFLEVTQQSmRADNQVNVTCQVTKFYPQRLQLTWLENGN--VSRTEMASALPENkDGTYNwtSWLLVNVSAHRDDVkLT 329
Cdd:cd21820     5 PPKAHVTHHP-RSEDEVTLRCWALGFYPADITLTWQLNGEelTQDMELVETRPAG-DGTFQ--KWAAVVVPLGKEQY-YT 79

                  ....*....
gi 1622839945 330 CQVEHDGQP 338
Cdd:cd21820    80 CHVYHEGLP 88

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) gamma chain; The members here are composed of the immunoglobulin (Ig) variable (V) domain of the gamma chain of gamma/delta T-cell receptors (TCRs). TCRs mediate antigen recognition by T lymphocytes, and are heterodimers consisting of alpha and beta chains or gamma and delta chains. Each chain contains a variable (V) and a constant (C) region. The majority of T cells contain alpha/beta TCRs, but a small subset contain gamma/delta TCRs. Alpha/beta TCRs recognize antigens as peptide fragments presented by major histocompatibility complex (MHC) molecules. Gamma/delta TCRs recognize intact protein antigens directly without antigen processing and recognize MHC independently of the bound peptide. Gamma/delta T cells can also be stimulated by non-peptide antigens such as small phosphate- or amine-containing compounds. The variable domain of gamma/delta TCRs is responsible for antigen recognition and is located at the N-terminus of the receptor. Members of this group contain the standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  38 QPEKSVSVAAGDSATLNCTVTSL-IPVGPIQWFR---GAGPGReLIY------HQKEGHFP--RVTSVSESTKRNnmdFS 105
Cdd:cd04982     3 QPQLSITREESKSVTISCKVSGIdFSTTYIHWYRqkpGQALER-LLYvsstsaVRKDSGKTknKFEARKDVGKST---ST 78

                          90       100       110
                  ....*....|....*....|....*....|....*....
gi 1622839945 106 IHISNITPADAGTYYCVKFRKGSpDVEVKS-GAGTELSV 143
Cdd:cd04982    79 LTITNLEKEDSATYYCAYWESGS-GYYIKVfGSGTKLIV 116

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        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945 147 PSAPVVSGPAVRATAEHTVSFTCESHGFSPR-DItlKWFKNGNELSDFQTNVDPAGKSVSYSIRSTARVVLSRRDVHSQV 225
Cdd:cd05884     5 PEKPQISGFTSPVMEGDHIQLTCKTSGSKPAaDI--RWFKNDKEVKDVKYLKAEDANRKTFTVSSSLDFHVDRDDDGVAI 82

                          90
                  ....*....|...
gi 1622839945 226 ICEVAHVTLQGDP 238
Cdd:cd05884    83 TCRVDHESLTATP 95

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DP; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DP. HLA class II histocompatibility antigen, DP(W2) beta chain is a protein that in humans is encoded by the HLA-DPB1 gene. It plays a central role in the immune system by presenting peptides derived from extracellular proteins. MHC class II molecules are encoded by three different loci, HLA-DR, -DQ, and -DP, which are about 70% similar to each other. HLA-DP is an alphabeta heterodimer cell-surface receptor. Each DP subunit (alpha-subunit, beta-subunit) is composed of a alpha-helical N-terminal domain, an IgG-like beta sheet, a membrane spanning domain, and a cytoplasmic domain. The alpha-helical domain forms the sides of the peptide binding groove. The beta sheet regions form the base of the binding groove and the bulk of the molecule as well as the inter-subunit (non-covalent) binding region. Individuals carrying the MHCII allele, HLA-DP2, are at risk for chronic beryllium disease (CBD), a debilitating inflammatory lung condition caused by the reaction of CD4 T cells to inhaled beryllium. MHC class II molecules play a key role in the initiation of the antigen-specific immune reponse. These molecules have been shown to be expressed constitutively on the cell surface of professional antigen-presenting cells (APCs), including B-lymphocytes, monocytes, and macrophages in both humans and mice. The expression of these molecules has been shown to be induced in nonprofessional APCs such as keratinocyctes, and they are expressed on the surface of activated human T cells and on T cells from other species. The MHC II molecules present antigenic peptides to CD4(+) T-lymphocytes. These peptides derive mostly from proteolytic processing via the endocytic pathway, of antigens internalized by the APC. These peptides bind to the MHC class II molecules in the endosome before they are transported to the cell surface. MHC class II molecules are heterodimers, comprised of two similarly-sized membrane-spanning chains, alpha and beta. Each chain had two globular domains (N- and C-terminal), and a membrane-anchoring transmembrane segment. The two chains form a compact four-domain structure. The peptide-binding site is a cleft in the structure.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1622839945 271 TCQVTKFYPQRLQLTWLENGnvsRTEMASALPENKDGTYNWTSWLLV--NVSAHRDDVkLTCQVEH 334
Cdd:cd21003    23 VCHVTDFYPGNIQVRWFLNG---QEETAGVVSTNLIHNGDWTFQILVmlEMTPQQGDV-YTCQVEH 84

Immunoglobulin (Ig) lambda light chain variable (V) domain; The members here are composed of the immunoglobulin (Ig) light chain, lambda type, variable (V) domain. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains (alpha, gamma, delta, epsilon, and mu), which determines the type of immunoglobulin formed: IgA, IgG, IgD, IgE, and IgM, respectively. In higher vertebrates, there are two types of light chain, designated kappa and lambda, which seem to be functionally identical, and can associate with any of the heavy chains. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1622839945  36 VIQPEkSVSVAAGDSATLNCTVTSL-IPVGPIQWF--RGAGPGRELIY---HQKEGHFPRVTSVSESTKRnnmdfSIHIS 109
Cdd:cd04984     2 LTQPS-SLSVSPGETVTITCTGSSGnISGNYVNWYqqKPGSAPRYLIYedkHRPSGIPDRFSGSKSGNTA-----SLTIS 75

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1622839945 110 NITPADAGTYYCVKFRKGSpdveVKSGAGTELSV 143
Cdd:cd04984    76 GAQTEDEADYYCQVWDSNS----YVFGGGTKLTV 105

CH2 domain (second constant Ig domain of the heavy chain) in immunoglobulin mu chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin constant domain (IgC) of mu heavy chains. This domain is found on the Fc fragment. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda; each is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1622839945 272 CQVTKFYPQRLQLTWLENGN--VSRTEMASALP-ENKDGTYNWTSWLLVNVSAHRDDVKLTCQVEHDG 336
Cdd:cd16093    24 CLATGFSPKTISFKWLRNGKevTSSTGAVVEEPkEDGKTLYSATSFLTITESEWKSQTEFTCEFKHKG 91