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Updated: Sep 27, 2026

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Activation of C-terminal Src kinase (Csk) by phosphorylation at serine-364 depends on the Csk-Src homology 3 domain
Sheraz Yaqub1, Hilde Abrahamsen, Bastian Zimmerman
1Department of Medical Biochemistry, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1112, Blindern, N-0317 Oslo, Norway.
Abstract:
In the present study, we investigate the mechanism for the protein kinase A (PKA)-mediated activation of C-terminal Src kinase (Csk). Although isolated Csk kinase domain was phosphorylated at Ser(364) by PKA to the same stoichiometry as wild-type Csk, significant activation of the isolated Csk kinase domain by PKA was observed only in the presence of the purified Src homology 3 domain (SH3 domain). Furthermore, the interaction between the SH3 and kinase domains was facilitated by PKA-mediated phosphorylation of the kinase domain, as evaluated by surface plasmon resonance. This suggests that an overall structural domain organization and interaction between the kinase and SH3 domains are important for the activity of Csk and its regulation by PKA.
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