C-src tyrosine kinase

C-src tyrosine kinase, also known as CSK, is a human protein and gene. It includes an SH2 domain, an SH3 domain, and a tyrosine kinase domain. This protein specifically phosphorylates Tyr-504 residue on human leukocyte-specific protein tyrosine kinase, which acts as a negative regulatory site. It may also act on the LYN and FYN kinases.