Métabolisme et fonctions de l’acide myristique

Metabolism and the functions of myristic acid

Institut national de la recherche agronomique, 65, rue de Saint-Brieuc, CS 84215, 35042 Rennes Cedex France

Résumé

L’acide myristique (C:14:0) est un acide gras saturé d’origine alimentaire ou d’origine endogène, encore peu connu. Il a des spécificités métaboliques et fonctionnelles qui sont présentées ici. Il possède un avenir court dans la cellule puisqu’il est majoritairement beta-oxydé et/ou allongé en acide palmitique. Il a également, en acylant plusieurs protéines (myristoylation), des rôles fonctionnels très importants dans la régulation de certaines fonctions cellulaires.

Abstract

Myristic acid metabolism, utilization, and biosynthesis in the cell remain unclear. Myristic acid usually accounts for small amounts of total fatty acids in animal tissues, but is more abundant in milk fat or in copra and palmist oil. Dietary saturated fat containing myristate (C14:0), but also laurate (C12:0) and palmitate (C16:0), is generally considered to induce an increase in plasma cholesterol. However, myristic acid exhibits other important specific functions: it is known to modify a number of proteins of both eukaryotic and viral origin by acylation. N-myristoylated proteins have several biological functions, such as signal transduction pathways, vesicular trafficking and structural roles, which depend on the presence of myristic acid in the cells. Therefore, myristic acid could play an important role in cell regulation. This report examines the recent data describing the metabolism and function of myristic acid. The origin (endogenous or dietary) of myristic acid, its uptake by the cell, incorporation into lipids, beta-oxydation rate, conversion to other fatty acids by elongation and desaturation, and the acylation of proteins by this fatty acid are discussed.