ITAMs: immunoregulatory scaffolds that link immunoreceptors to their intracellular signaling pathways.
Antigen receptors on the surface of T and B lymphocytes and various immunoglobulin Fc receptors are complexed multi-subunit structures that possess unique cytoplasmic modules, termed immunoreceptor tyrosine-based activation motif (ITAM). These modules consist of two repeats of the conserved sequence Tyr-X-X-Leu/lle spaced by six-to-eight residues and they function as 'on and off' switches that link the receptors to their intracellular signaling machinery. Thus, engagement of ITAM-containing receptors results in a rapid and transient phosphorylation of the ITAMs' tyrosine residues that function as temporal scaffolds for Src homology 2 (SH2) domains of downstream effector molecules. Recruitment and binding of these molecules to phospho-ITAMs initiate a cascade of biochemical events that lead to cell proliferation, differentiation, and acquisition of unique effector functions.
Department of Microbiology and Immunology, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel. noah@bgumail.bgu.ac.il
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D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000276:immunology*; D011971:Receptors, Immunologic / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D018160:Receptors, Cytoplasmic and Nuclear; D011971:Receptors, Immunologic