Endocrinology, Vol 113, 758-762, Copyright © 1983 by Endocrine Society

ARTICLES

Hormonal activation of phospholipid methyltransferase in the Leydig cell

A Nieto and KJ Catt

Hormonal stimulation of purified rat Leydig cells with hCG caused a 2- fold increase in phospholipid methyltransferase activity within 10 min. This effect of gonadotropin was concentration dependent, with maximal activation of methyltransferase at 10(-12) M hCG, and was reproduced by 8-bromo-cAMP. Hormonal activation of phospholipid methyltransferase caused an increase in the maximum velocity of the enzyme, without changing the Km for S-adenosylmethionine. Analysis of the pattern of radiolabeled phospholipids from Leydig cells showed that the incorporation of methyl groups and the increase in phospholipid methylation stimulated by 8-bromo-cAMP occurred mainly in phosphatidyl- N-monomethylethanolamine. The rapid and highly sensitive increase in phospholipid methylation in hCG-stimulated Leydig cells is consistent with a role of methyltransferase in the hormonal activation mechanism probably at a step subsequent to cAMP production.

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				D. J. Shields, R. Lehner, L. B. Agellon, and D. E. Vance Membrane Topography of Human Phosphatidylethanolamine N-Methyltransferase J. Biol. Chem., January 24, 2003; 278(5): 2956 - 2962. [Abstract] [Full Text] [PDF]