Protein tyrosine kinase Syk in mast cell signaling.

The tyrosine kinase Syk is essential for signaling from FcrepsilonRI in mast cells. The Src homology domain mediated binding of Syk to the phosphorylated immunoreceptor tyrosine-based motif (ITAM) of the receptor subunits results in a conformational change and activation. Studies in Syk deficient mast cells have defined the pathways that are activated upstream and downstream of Syk and have demonstrated the functional importance of the linker region of Syk in signaling in mast cells.