Activation of Pyk2/RAFTK induces tyrosine phosphorylation of alpha-synuclein via Src-family kinases.

alpha-Synuclein (alpha S) is a neuronal protein that has been implicated in the pathogenesis of Parkinson's disease. The present report demonstrates that the protein tyrosine kinase Pyk2/RAFTK is involved in cell stress-induced tyrosine phosphorylation of alpha S. Hyperosmotic stress induced tyrosine phosphorylation of alpha S via Pyk2/RAFTK at tyrosine residue 125. Pyk2/RAFTK-mediated phosphorylation of alpha S was primarily achieved with Src-family kinases. In addition, osmotic stress-induced phosphorylation of alpha S was dependent on Pyk2/RAFTK activation. Accordingly, such results indicate that Pyk2/RAFTK lies upstream of Src-family kinases in the signaling cascade by which osmotic stress induces tyrosine phosphorylation of alpha S.