THE DEPHOSPHORYLATION CHARACTERISTICS OF THE RECEPTORS FOR EPIDERMAL GROWTH-FACTOR AND PLATELET-DERIVED GROWTH-FACTOR IN SWISS 3T3-CELL MEMBRANES SUGGEST DIFFERENTIAL REGULATION OF RECEPTOR SIGNALING BY ENDOGENOUS PROTEIN-TYROSINE PHOSPHATASES

Comparison of the phosphotyrosine-specific dephosphorylation of the autophosphorylated receptors for epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) in Swiss 3T3 cell membranes by the endogenous phosphatases revealed striking differences. EGF receptor dephosphorylation was clearly faster than PDGF receptor dephosphorylation and strongly inhibited by Triton X-100 and octylglucoside, whereas PDGF receptor dephosphorylation was to a lesser extent detergent-susceptible. PDGF receptor dephosphorylation was effectively inhibited by phenylarsineoxide, protamine and poly-lysine and partially by N-ethylmaleinimide, whereas EGF receptor dephosphorylation was not affected by these agents. We suggest that these differences in dephosphorylation of EGF and PDGF receptors are due to their differential interaction with membrane-associated protein-tyrosine phosphatases and important for differential regulation of receptor signalling.