Cloning, Expression, and Nutritional Regulation of the Mammalian Δ-6 Desaturase

摘要: Arachidonic acid (20:4(n-6)) and docosahexaenoic (22:6(n-3)) have a variety of physiological functions that include being the major component membrane phospholipid in brain retina, substrates for eicosanoid production, regulators nuclear transcription factors. The rate-limiting step production 20:4(n-6) 22:6(n-3) is desaturation 18:2(n-6) 18:3(n-3) by Delta-6 desaturase. In this report, we describe cloning, characterization, expression mammalian open reading frames mouse human desaturase each encode 444-amino peptide, two peptides share an 87% amino homology. sequence predicts peptide contains membrane-spanning domains as well cytochrome b5-like domain characteristic nonmammalian desaturases. Expression frame rat hepatocytes Chinese hamster ovary cells instilled these ability to convert their respective products, 18:3(n-6) 18:4(n-3). When mice were fed diet containing 10% fat, hepatic enzymatic activity mRNA abundance corn oil 70 50% lower than triolein. Finally, Northern analysis revealed contained amount was several times greater found other tissues including liver, lung, heart, skeletal muscle. RNA data indicate prior conclusions regarding low level nonhepatic may need be reevaluated.