c-Src was the first proto-oncogenic non-receptor tyrosine kinase characterized in human. The Src family is composed of nine members in vertebrates, including c-Src, Yes, Fgr, Yrk, Fyn, Lyn, Hck, Lck, and Blk. Src-family kinases transduce signals that are involved in the control of a variety of cellular processes, including proliferation, differentiation, motility, and adhesion. Src-family kinases contain an N-terminal cell membrane anchor followed by SH3 and SH2 domains. The activity of c-Src is regulated by tyrosine phosphorylation at multiple sites. Tyrosine 418 is autophosphorylated following c-Src activation. Tyrosine 215 in the SH2 domain of c-Src is phosphorylated following growth factor receptor activation. Both Tyr-215 and Tyr-418 phosphorylation increases tyrosine kinase activity, while phosphorylation of Tyr-530 downregulates c-Src kinase activity. Thus, tyrosine phosphorylation of c-Src is critical for regulating its kinase activity.
