IDENTIFICATION AND CHARACTERIZATION OF A NOVEL SYNTHETIC PEPTIDE SUBSTRATE-SPECIFIC FOR SRC-FAMILY PROTEIN-TYROSINE KINASES

Using a random combinatorial peptide library method [Wu, J., Ma, Q. N. and Lam, K. S. (1994) Biochemistry 33, 14825-14833] a novel peptide, YIYGSFK, was identified as a substrate for p60(c-src) protein tyrosine kinase. Mass spectrometric analysis showed that tyrosine-3 from the N-terminus was the phosphorylation site. Kinetic studies showed that the K-m of YIYGSFK for p60(c-src) was 55 mu M, about 6.4-fold lower than a peptide derived from p34(cdc2) [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. (C) Munksgaard 1995.