Membrane-Associated N-Myristoyltransferase Activity Is Reduced in Obese (fa/fa) Zucker Rat Liver

• Published in: Biochemical and biophysical research communications Vol. 196; no. 2; pp. 665 - 670
• Main Authors: King, M.J., Pugazhenthi, S., Khandelwal, R.L., Sharma, R.K.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 29.10.1993; Elsevier
• Subjects: ACIDE MYRISTIQUE; ACIDO MIRISTICO; ACILTRANSFERASA; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ACYLTRANSFERASE; Acyltransferases - metabolism; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Blood Glucose - metabolism; Body Weight - drug effects; Brain - enzymology; Cell Membrane - enzymology; DIABETE; DIABETES; Diabetes Mellitus - enzymology; Diabetes Mellitus, Type 2 - enzymology; Enzymes and enzyme inhibitors; FOIE; Fundamental and applied biological sciences. Psychology; HIGADO; Insulin - blood; Liver - drug effects; Liver - enzymology; Male; MEMBRANA; MEMBRANE; Obesity - enzymology; Obesity - genetics; PLASMA SANGUIN; PLASMA SANGUINEO; RAT; RATA; Rats; Rats, Sprague-Dawley; Rats, Zucker - metabolism; SOBREPESO; SURPOIDS; Transferases; Vanadates - pharmacology; VANADIO; VANADIUM; Acyltransferases; Animal model; Rat; Enzyme; Transferases; Liver; Rodentia; Non insulin dependent diabetes; Glycylpeptide N-tetradecanoyltransferase; Vertebrata; Mammalia; Enzymatic activity; Brain (vertebrata)
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1993.2301

N-Myristoyltransferase is the enzyme that catalyses the transfer of myristate from myristoyl-CoA to the NH 2-terminal glycine residue of a number of protein of diverse functions. Many of the known myristoylated proteins are important in signal transduction. We have compared the activity of rat liver N-myristoyltransferase from lean and obese (fa/fa) Zucker rats (a model for non-insulin dependent diabetes mellitus, NIDDM). N-myristoyltransferase activity isolated from the particulate fraction of obese (fa/fa) Zucker rat liver was ∼4.7-fold lower than the corresponding activity observed in either the controls or the vanadate-treated obese rat livers. This pattern was only observed in the particulate fraction; the homogenate and soluble N-myristoyltransferase activities were not significantly different to the control activities. N-myristoyltransferase activity isolated from the brain of the four groups showed no significant variations. These results, and previous work [King, M. J., Pugazhenthi, S., Khandelwal, R. L. and Sharma, R. K. (1993) Biochim. Biophys. Acta. 1165, 259-262], 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. The specific activity of the particulate liver N-myristoyltransferase was approximately 10-fold higher than that of the soluble liver N-myristoyltransferase, raising the possibility that N-myristoyltransferase exists in 2 populations, with the active form of N-myristoyltransferase residing in the membranous fraction. This situation could provide a system whereby N-myristoylation is regulated by the translocation of N-myristoyltransferase from the cytosol to its active site in the membranes.