In vivo modulation of N-myristoyltransferase activity by orthovanadate

N-Myristoyltransferase (NMT) catalyses the transfer of myristate from myristoyl-CoA to the NH₂-terminal glycine residue of several proteins and are important in signal transduction. STZ-induced diabetes (an animal model for insulin-dependent diabetes mellitus, IDDM) resulted in a 2-fold increase in rat liver NMT activity as compared with control animals. In obese Zucker (fa/fa) rats (an animal model for non-insulin dependent diabetes mellitus, NIDDM) there was a4.7-fold lower liver particulate NMT activity as compared with the control lean rat livers. Administration of sodium orthovanadate to the diabetic rats normalised liver NMT activity. These results would indicate that the rat liver particulate N-myristoyltransferase activity appears to be inversely proportional to the level of plasma insulin, implicating insulin in the control of N-myristoylation.Abbreviations NMT N-myristoyl-CoA:protein N-myristoyltransferase - IDDM insulin-dependent diabetes mellitus - NIDDM non-insulin-dependent diabetes mellitus - NIP₇₁ 71 kDa N-myristoyltransferase inhibitor protein - NAF₄₅ 45 kDa N-myristoyltransferase activating factor