Identification and characterization of a novel synthetic peptide substrate specific for Src‐family protein tyrosine kinases

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Abstract
Using a random combinatorial peptide library method [Wu, J., Ma, Q. N. & Lam, K. S. (1994) Biochemistry33, 14825–14833] a novel peptide, YIYGSFK, was identified as a substrate for p60c-src protein tyrosine kinase. Mass spectrometric analysis showed that tyrosine-3 from the N-terminus was the phosphorylation site. Kinetic studies showed that the Km of YIYGSFK for p60c-src was 55 μM, about 6.4-fold lower than a peptide derived from p34cdc2 [cdc2(6–20), KVEKIGEGTYGVVYK], which had been reported to be a specific and efficient substrate for the Src-family protein tyrosine kinases. Comparison of the specificity of YIYGSFK and cdc2(6–20) as a substrate for various Src-family and non-Src-family protein tyrosine kinases suggests that YIYGSFK is a much more specific and efficient substrate for the Src-family protein tyrosine kinases. © Munksgaard 1995.