Phosphorylation of a synthetic gastrin peptide by the tyrosine kinase of A431 cell membranes

Abstract

The peptide Arg.Arg.Leu.Glu.Glu.Glu.Glu.Glu.Ala.Tyr.Gly was synthesized as an analogue of residues 20-30 of human gastrin 34. The epidermal growth factor-stimulated tyrosine kinase of A431 cell membranes phosphorylated the peptide's single tyrosine residue. Km values of 0.11 and 0.61mM and Vmax values of 1.71 and 0.68nmol/min/mg were obtained in the presence and absence of epidermal growth factor respectively. This is the first report of phosphorylation of tyrosine in a sequence related to a human hormone. © 1982.