Elevated N-myristoyl transferase activity is reversed by sodium orthovanadate in streptozotocin-induced diabetic rat.

N-Myristoyl transferase (NMT) is the enzyme that covalently modifies several proteins important in signal transduction. Streptozotocin-induced diabetes resulted in a 2-fold increase in NMT activity from rat liver as compared to control animals. Administration of sodium orthovanadate to the diabetic rats reduced the activity of the NMT to 75-120% of the control values. Elevated NMT activity was observed with both cAMP-dependent protein kinase-derived and pp60src-derived peptide substrates. No significant change in the apparent Km was observed with the cAMP-dependent protein kinase-derived peptide substrate. Unlike in rat brain, in all conditions highest NMT activity was observed in the particulate fraction of rat liver.