Clone REA500 recognizes the human CrkL antigen phosphorylated at tyrosine 207 (pY207). CRKL is a member of adaptor proteins that participate in signal transduction in response to both extracellular and intracellular stimuli, such as growth factors, cytokines, and the oncogenic BCR-ABL fusion protein. CRKL consists of an N-terminal Src homology 2 (SH2) domain followed by two SH3 domains (SH2-SH3N-SH3C). The SH2 domain of CRKL binds to phosphorylated Y-x-x-P motif present in many docking proteins, such as BCAR1, Paxillin, and GAB, whereas the SH3N domain binds to proline-rich P-x-x-P-x-K motif-containing proteins, such as Son of Sevenless (SOS), RAPGEF1, p85, ABL1, and BCR-ABL. Through these interactions, CRKL facilitates the timely and localized formation of protein complexes required for signal transduction in many biological processes including cell proliferation, survival, adhesion, and migration. CRKL is preferentially expressed in hematopoietic cells. Y207 in CRKL represents the major

phosphorylation site. It is phosphorylated in hematopoietic cells that express the BCR-ABL fusion protein. Phosphorylation of Y207 provides a binding site for the CRKL SH2 domain and potentially for other SH2-containing proteins.