Signaling Pathways That Regulate Effector Function: Perspectives

The β- and γ-subunits of FceRI transduce the signals generated by aggregation of this receptor.1 The cytoplasmic domains of both these subunits contain a motif with the amino acid sequence (D/E)x2Yx2Lx6–8Yx2(L/I) that is essential for cell activation.2–5 This immunoreceptor tyrosine-based activation motif (ITAM) is also present in the subunits of the T-cell and B-cell antigen receptors.4,6–10 The aggregation of these receptors results in phosphorylation of the tyrosine residues within the ITAM, which is critical for cell signaling.6–9