Phosphotyrosine Signaling: Evolving a New Cellular Communication System

Tyrosine phosphorylation controls many cellular functions. Yet the three-part toolkit that regulates phosphotyrosine signaling—tyrosine kinases, phosphotyrosine phosphatases, and Src Homology 2 (SH2) domains—is a relatively new innovation. Genomic analyses reveal how this revolutionary signaling system may have originated and why it rapidly became critical to metazoans.