We thank J. F. Sperry and P. S. Cohen for critically reading the manuscript, P. A. Cole (The Johns Hopkins University, Baltimore) for providing pREP4groESL plasmid, and R. Jove (University of South Florida, Tampa) for providing pMcSrc Met-295 plasmid. DNA sequencing was performed at the University of Rhode Island Genomics and Sequencing Center. This work was supported by grants from the National Institutes of Health (1 P20 RR16457) and the University of Rhode Island Research Council.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: Csk, C-terminal Src kinase; Chk, Csk-homologous kinase; DM, double mutant; kdSrc, kinase-defective Src that contains a Lys295Met mutation; PTK, protein tyrosine kinase; SFK, Src family PTK; QM, quadruple mutant; SH, Src homology; Yact, the Tyr residue in the activation loop; Ytail, the Tyr residue in the C-terminal tail of Src family kinases.