title: The role of the protein tyrosine phosphatase CD45 in regulation of B lymphocyte activation.
abstract: The transmembrane protein tyrosine phosphatase CD45 is expressed throughout B cell development and differentiation, with the exception of terminally differentiated plasma cells on which its expression is down regulated. Numerous studies using CD45-deficient B cell lines and CD45-deficient mice have clearly demonstrated that CD45 plays an important role in modulating the signal that is transduced via the B cell antigen receptor by regulating the phosphorylation state of Src family kinases. Spatial and temporal controls enable CD45 to promote B cell antigen receptor signal transduction by constitutively maintaining Src family kinases in a partially active state, such that the B cell is able to effectively respond to an antigenic challenge. Moreover, CD45 is required for optimal activation of Ca2+-dependent and MAP kinase-dependent signal transduction pathways in the B cell. The net result is that CD45 affects the B cell response by controlling the relative threshold of sensitivity to a given antigenic stimulus. Thus, CD45 expression and function is required for normal B cell development, tolerance induction, and responsiveness to antigen.
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, 35294-3000, USA. louis.justement@ccc.uab.edu
authors.forename: L B
authors.initials: LB
authors.lastname: Justement
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000201:enzymology* / Q000276:immunology*; D002454:Cell Differentiation; D004792:Enzyme Precursors / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D017493:Leukocyte Common Antigens / Q000378:metabolism*; D008213:Lymphocyte Activation; D051379:Mice; D018345:Mice, Knockout; D018448:Models, Immunological; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D015398:Signal Transduction; D000072377:Syk Kinase; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D011947:Receptors, Antigen, B-Cell; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606897:Syk protein, mouse; D019061:src-Family Kinases; D017493:Leukocyte Common Antigens; D017027:Protein Tyrosine Phosphatases