ON THE TYROSINE KINASE MECHANISM OF THE NOVEL EFFECT OF INSULIN AND INSULIN-LIKE GROWTH-FACTOR-I - STIMULATION OF THE ADENYLYL-CYCLASE SYSTEM IN MUSCLE-TISSUE

For the first time, insulinlike growth factor I (IGF-I), like insulin (Pertseva et al., Comp Biochem Physiol 112: 689-695, 1995), was shown to exercise a GTP-dependent stimulating action on adenylyl cyclase (AC ; EC 4.6.1.1.) activity in the muscle tissues (membrane fraction) of m ammal (rat) and mollusc (Anodonta cygnea). By studying the mechanism o f the effect of peptides with selective inhibitors of tyrosine kinase activity, tyrphostin 47 (RG50864, 3,4-dihydroxy-alpha-cyanothiocinnama mide) and genistein (4,5,7-trihydroxyisoflavone), it was found that re ceptor tyrosine kinase is involved in this action. The data obtained s uggest that the stimulating effect of insulin and IGF I is produced vi a the following signalling system: receptor tyrosine kinase --> stimul atory G-protein --> AC. Thus, the existence of a novel signalling path way of transduction of signals generated by insulin and related peptid es was hypothesised. Copyright (C) 1996 by Elsevier Science Inc.