Anti-Crk II (Tyr-221), Phosphospecific Antibody

The Crk family of adaptor proteins (Crk I, Crk II and CrkL) are Src Homology 2 (SH2) and Src Homology 3 (SH3) domain-containing proteins that form protein complexes important for transmiting signals downstream of tyrosine kinases. Both Crk II and CrkL are composed of a single SH2 domain, followed by two tandem SH3 domains. Crk II is also alternatively spliced to a minor product, Crk I, which is structurally and functionally more similar to the v-Crk oncogene. Both Crk II and CrkL are ubiquitously expressed and their SH domains are highly homologous, however both are required for mouse development and have distinct non-overlapping phenotypes in knockout mice. Phosphorylation may be important for regulating Crk activity. Crk II Tyr-221 (CrkL Tyr-207) phosphorylation is a negative regulatory site, while Crk Tyr-251 phosphorylation in the SH3 domain is a positive regulatory site. EGF stimulation induces phosphorylation of Tyr-251, which increases binding of Crk to the SH2 domain of Abl, and promotes transactivation of Abl.