CD45: a receptor type protein tyrosine phosphatase protein. Contains an extracellular domain, a single transmembrane segment and two tandem intracytoplasmic catalytic domains. The first PTPAse domain has enzymatic activity, while the second one seems to affect the substrate specificity of the first one. Specifically expressed in hematopoietic cells. An essential regulator of T- and B-cell antigen receptor signaling. Functions through either direct interaction with components of the antigen receptor complexes, or by activating various Src family kinases required for the antigen receptor signaling. Suppresses JAK kinases, and thus functions as a regulator of cytokine receptor signaling. Four alternatively spliced isoforms have been described.
Protein type: Membrane protein, integral; Motility/polarity/chemotaxis; Receptor protein phosphatase, tyrosine; EC 3.1.3.48
Cellular Component: internal side of plasma membrane; cell surface; focal adhesion; membrane; integral to plasma membrane; integral to membrane; plasma membrane; intracellular; cytosol; lipid raft; external side of plasma membrane
Molecular Function: heparin binding; heparan sulfate proteoglycan binding; protein binding; transmembrane receptor protein tyrosine phosphatase activity; protein tyrosine phosphatase activity; protein kinase regulator activity; protein kinase binding
Biological Process: B cell proliferation; positive regulation of isotype switching to IgG isotypes; activation of MAPK activity; regulation of humoral immune response mediated by circulating immunoglobulin; positive regulation of T cell mediated cytotoxicity; regulation of cell cycle; protein amino acid dephosphorylation; T cell receptor signaling pathway; T cell proliferation; leukocyte adhesion; B cell receptor signaling pathway; positive regulation of MAPKKK cascade; negative regulation of T cell mediated cytotoxicity; positive regulation of B cell proliferation; response to gamma radiation; positive regulation of T cell mediated immunity; positive regulation of T cell proliferation; negative regulation of protein amino acid autophosphorylation; negative regulation of cytokine and chemokine mediated signaling pathway; positive regulation of gamma-delta T cell differentiation; defense response to virus; positive thymic T cell selection; T cell differentiation; regulation of B cell receptor signaling pathway; positive regulation of humoral immune response mediated by circulating immunoglobulin; negative regulation of peptidyl-tyrosine phosphorylation; substrate-bound cell migration, cell release from substrate; negative thymic T cell selection; positive regulation of antigen receptor-mediated signaling pathway; bone marrow development; heterotypic cell-cell adhesion; stem cell development; positive regulation of T cell differentiation; dephosphorylation; B cell differentiation; release of sequestered calcium ion into cytosol; regulation of B cell differentiation; negative regulation of protein kinase activity; positive regulation of alpha-beta T cell proliferation; hemopoietic progenitor cell differentiation; immunoglobulin biosynthetic process
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