Immunoglobulin superfamily (IgSF) members are classified into one superfamily because of the common structure called immunoglobulin domain or immunoglobulin fold. There are a several types of IgSF members, including surface antigen receptors, co-receptors of the immune system, cell adhesion molecules and so on. The details of subfamilies in immunoglobulin superfamily are listed as the following:
Antigen receptors. This class of IgSF members is called immunoglobulins or antibodies and T cell receptor (TCR) chains. Antigen receptors are found on the cell surface of T and B cells in all jawed vertebrates. There are 5 kinds of immunoglobulin in humans which all composed of a heavy chain with 4 immunoglobulin (Ig) domains and a light chain with two Ig domains. The TCP chains contain TCR-alpha and -beta chains, or the TCR-delta and gamma chains with 2 Ig domains, 1 IgV domain and 1 IgC1 domain.
Antigen presenting molecules. This class of IgSF members contains Class I MHC (major histocompatibility complex), Class II MHC and beta-2 microglobulin as ligands for TCRs.
Antigen receptor accessory molecules. This class of IgSF members contains CD3-γ, -δ and -ε chains, CD79a and CD79b. CD3 is a molecule transmiting signals from the TCRs. CD3 molecules have a single Ig domain. CD79 proteins possess a single Ig domain and function as co-receptors and accessory molecules in the cell activation by immunoglobulin.
Co-receptors. This class of IgSF members is composed of CD4, CD8 and CD19. These proteins also interact with MHC molecules. CD4 molecule has 4 Ig domains. CD8 protein has 1 extracellular IgV domain and is a dimer composed of CD8 alpha and beta chain. CD19 protein has 2 IgC2-domains.
Co-stimulatory/inhibitory molecules. This class of IgSF members is composed of CD28, CD80 and CD86. These molecules function to regulate the activation, effector functions and expansion of cells.
There are also several other subfamilies in immunoglobulin superfamily, including Growth factor receptors, Ig binding receptors, IgSF CAMs, Receptors on Natural killer cells, Receptors on Leukocytes, Receptors of Cytokine, Receptor tyrosine kinases/phosphatases and others (such as CD7, CD90,CD147, Butyrophilins (Btn) and Titin).
Immunoglobulin Superfamily Members related literatures
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2. Mendelsohn C L, Wimmer E, Racaniello V R. Cellular receptor for poliovirus: molecular cloning, nucleotide sequence, and ex
3. Lander E S, Linton L M, Birren B, et al. Initial sequencing and analysis of the human genome[J]. Nature, 2001, 409(6822): 860-921.
4. Colonna M, Samaridis J. Cloning of immunoglobulin-superfamily members associated with HLA-C and HLA-B recognition by human natural killer cells[J]. Science, 1995, 268(5209): 405-408.
5. Williams A F. A year in the life of the immunoglobulin superfamily[J]. Immunology Today, 1987, 8(10): 298-303.