Regulation of antigen receptor signal transduction by protein tyrosine kinases.

The past two years have seen further clarification of the early events occurring in antigen receptor signal transduction that are mediated by the immunoreceptor tyrosine-based activation motif (ITAM). The ITAM was shown to be a specific binding site for the ZAP-70/Syk protein tyrosine kinases and the structure of this complex was solved. In addition, possible mechanisms of activation and functions for these kinases were reported. Lastly, genetic studies established the critical importance of these kinases in antigen-receptor signaling and lymphocyte development.