Csk-homologous kinase (Chk) is an efficient inhibitor of Src-family kinases but a poor catalyst of phosphorylation of their C-terminal regulatory tyrosine

• DOI: 10.1186/s12964-017-0186-x
• Publication Date: 2017-08-07T12:32:17Z
• Authors: Gahana Advani; Ya Chee Lim; Bruno Catimel; Daisy Sio Seng Lio; Nadia L. Y. Ng; Anderly C. Chüeh; Mai Tran; Mohd Ishtiaq Anasir; Heather Verkade; Hong-Jian Zhu; Benjamin E. Turk; Thomas E. Smithgall; Ching-Seng Ang; Michael Griffin; Heung-Chin Cheng
• Keywords: Tyrosine-protein kinase CSK; Src family kinase

C-terminal Src kinase (Csk) and Csk-homologous (Chk) are the major endogenous inhibitors of Src-family kinases (SFKs). They employ two mechanisms to inhibit SFKs. First, they phosphorylate tail tyrosine which stabilizes SFKs in a closed inactive conformation by engaging SH2 domain cis. Second, non-catalytic inhibitory mechanism involving direct binding Csk Chk active forms that is independent phosphorylation their tail. co-expressed many cell types. Contributions towards activity not fully clear. Furthermore, determinants governing inhibition yet be defined. We determined contributions both vitro transduced colorectal cancer cells. Specifically, we assayed catalytic activities phosphorylating specific peptide substrate recombinant SFK member Src. employed surface plasmon resonance spectroscopy measure kinetic parameters Csk, mutants constitutively mutant Hck. Finally, effects expression on anchorage-independent growth Chk-deficient Our results revealed as robust enzyme catalysing but weak inhibitor In contrast, poor catalyst binds with high affinity, enabling it efficiently Further analyses mapped some this its domain. activated different upstream signals adopt multiple conformations adopting these can effectively constrained complementary Chk. lack accounts for overactivation