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.
Isakov
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Department of Microbiology and Immunology, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel. noah@bgumail.bgu.ac.il
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