COMMON AND DIFFERENTIAL RECOGNITION OF STRUCTURAL FEATURES IN SYNTHETIC PEPTIDES BY THE CATALYTIC DOMAIN AND THE SRC-HOMOLOGY-2 (SH2) DOMAIN OF PP60(C-SRC)

The relative efficiencies of the catalytic domain of the src-family ki nase pp60(c-src) in phosphorylating four peptide substrates including (i) src-optimal peptide (AEEEI (Y) under bar GEFEAKKKK), (ii) ''-YEEI- peptide'' (KKTHQEEEEPQ (Y) under bar EEIPIYL), (iii) cdc2(6-20) (KVEKI GEGT (Y) under bar GVVYK), (iv) src-autophosphorylation site peptide ( ADFGLARLIEDNE (Y) under bar TARG) and the relative efficiencies of its SH2 domain in binding the phosphorylated forms of these peptide subst rates were compared. The results show that the src-optimal peptide, '' -YEEI-peptide,'' cdc2(6-20) peptide were phosphorylated by the catalyt ic domain with high efficiency and that the phosphorylated form of all three peptides could bind the SH2 domain of the kinase, confirming th e hypothesis proposed by Songyang and co-workers that the catalytic do main of pp60(c-src) phosphorylates sites which are recognized by its o wn SH2 domain (Songyang et al. (1995) Nature 373, 536-539). The four p eptides were phosphorylated by the kinase with relative efficiencies i n the order of Src-optimal peptide > ''-YEEI-peptide'' > cdc2(6-20) >> src-autophosphorylation site peptide. However, the Tyr(P)-Src-optimal peptide and [pY](15)cdc2(6-20) bound to the SH2 domain of the kinase with an affinity at least an order of magnitude lower than that of the tight-binding peptide, ''-pYEEI-peptide.'' Thus, our study suggests t hat the catalytic and SH2 domains of pp60(c-src) recognize overlapping but not identical determinants in the local structure around the tyro sine phosphorylation site of the substrate peptides. (C) Munksgaard 19 97.