An immunoreceptor tyrosine-based inhibition motif (ITIM), is a conserved sequence of amino acids (S/I/V/LxYxxI/V/L) that is found in the cytoplasmic tails of many inhibitory receptors of the immune system. After ITIM-possessing inhibitory receptors interact with their ligand, their ITIM motif becomes phosphorylated by enzymes of the Srckinase family, allowing them to recruit other enzymes such as the phosphotyrosinephosphatasesSHP-1 and SHP-2, or the inositol-phosphatase called SHIP. These phosphatases decrease the activation of molecules involved in cell signaling. A list of human candidate ITIM-containing proteins has been generated by proteome-wide scans.
^Barrow A, Trowsdale J (2006). "You say ITAM and I say ITIM, let's call the whole thing off: the ambiguity of immunoreceptor signaling". Eur J Immunol. 36 (7): 1646–53. doi:10.1002/eji.200636195. PMID16783855.