Comparison of tyrosine phosphorylation of proteins by membrane fractions from mouse liver, ehrlich ascites tumor and MH134 hepatoma

摘要

>When membrane fractions from mouse liver. Ehrlich ascites tumor and MH 134 hepatoma were incubated with [γ-32]ATP at O°C in the presence of MnCly ZnCl; and NaV0₃, proteins were phosphorylated on tyrosines to a larger extent in liver membranes than in tumor membranes. Separation of labelled proteins by SDS-gel electrophoresis showed phosphorylated alkali-resistant bands of 170, 140, 130, 80, 56, 53 and 46 kDa proteins in Ehrlich ascites tumor membranes; liver membranes exhibited more strongly phosphorylated bands of 170, 56, 53 and 46 kDa proteins. Epidermal growth factor stimulated the tyrosine phosphorylation of only a 170 kDa protein, which was more significant in liver membranes. Liver membranes exhibited slightly higher levels of tyrosine protein kinase activity compared to tumor membranes.