An immunoreceptor tyrosine-based activation motif (ITAM) is a protein motif found in some signaling molecules. This motif is composed of two tyrosine (Y) residues separated by 9–12 amino acids. The canonical sequence is YXX[L/V]X_6–9YXX[L/V] where X is any amino acid, L is leucine, and V is valine. Phosphorylation of the Y (tyrosine) residues recruits other proteins (with SH2 domains) to the signaling complex.

 Signal Transduction During Lymphocyte Activation