Component of a lipid metabolic pathway that catalyzes biosynthesis of highly unsaturated fatty acids (HUFA) from precursor essential polyunsaturated fatty acids (PUFA) linoleic acid (LA) (18:2n-6) and alpha-linolenic acid (ALA) (18:3n-3). Catalyzes the first and rate limiting step in this pathway which is the desaturation of LA (18:2n-6) and ALA (18:3n-3) into gamma-linoleic acid (GLA) (18:3n-6) and stearidonic acid (18:4n-3) respectively and other desaturation steps. Highly unsaturated fatty acids (HUFA) play pivotal roles in many biological functions. It catalizes as well the introduction of a cis double bond in palmitate to produce the mono-unsaturated fatty acid sapienate, the most abundant fatty acid in sebum.
Delta-6 desaturase, also known as fatty acid desaturase-2 (FADS2), is a component of a lipid metabolic pathway that converts the essential fatty acids linoleate and alpha-linolenate into long-chain polyunsaturated fatty acids. Isolation of Delta-6 desaturase/FADS2 cDNA from human skin predicts an identical protein to that expressed in human brain and Southern analysis indicates a single locus, together suggestive of a single Delta-6 desaturase/FADS2 gene. Within human skin, Delta-6 desaturase/FADS2 mRNA and protein expression is restricted to differentiating sebocytes located in the suprabasal layers of the sebaceous gland. Enzymatic analysis using CHO cells overexpressing human Delta-6 desaturase/FADS2 indicates catalysis of a "polyunsaturated fatty acid type" reaction, but also an unexpected "sebaceous-type" reaction, that of converting palmitate into the mono-unsaturated fatty acid sapienate, a 16-carbon fatty acid with a single cis double bond at the sixth carbon from the carboxyl end. Sapienate is the most abundant fatty acid in human sebum, and among hair-bearing animals is restricted to humans. This work identifies Delta-6 desaturase/FADS2 as the major fatty acid desaturase in human sebaceous glands and suggests that the environment of the sebaceous gland permits catalysis of the sebaceous-type reaction and restricts catalysis of the polyunsaturated fatty acid type reaction.
J. Biol. Chem. 274, 471-477 (1999)[PubMed:9867867]
Arachidonic acid (20:4(n-6)) and docosahexaenoic acid (22:6(n-3)) have a variety of physiological functions that include being the major component of membrane phospholipid in brain and retina, substrates for eicosanoid production, and regulators of nuclear transcription factors. The rate-limiting step in the production of 20:4(n-6) and 22:6(n-3) is the desaturation of 18:2(n-6) and 18:3(n-3) by Delta-6 desaturase. In this report, we describe the cloning, characterization, and expression of a mammalian Delta-6 desaturase. The open reading frames for mouse and human Delta-6 desaturase each encode a 444-amino acid peptide, and the two peptides share an 87% amino acid homology. The amino acid sequence predicts that the peptide contains two membrane-spanning domains as well as a cytochrome b5-like domain that is characteristic of nonmammalian Delta-6 desaturases. Expression of the open reading frame in rat hepatocytes and Chinese hamster ovary cells instilled in these cells the ability to convert 18:2(n-6) and 18:3(n-3) to their respective products, 18:3(n-6) and 18:4(n-3). When mice were fed a diet containing 10% fat, hepatic enzymatic activity and mRNA abundance for hepatic Delta-6 desaturase in mice fed corn oil were 70 and 50% lower than in mice fed triolein. Finally, Northern analysis revealed that the brain contained an amount of Delta-6 desaturase mRNA that was several times greater than that found in other tissues including the liver, lung, heart, and skeletal muscle. The RNA abundance data indicate that prior conclusions regarding the low level of Delta-6 desaturase expression in nonhepatic tissues may need to be reevaluated.
A process in which a series of electron carriers operate together to transfer electrons from donors to any of several different terminal electron acceptors to generate a transmembrane electrochemical gradient.
The chemical reactions and pathways resulting in the formation of an unsaturated fatty acid, any fatty acid containing one or more double bonds between carbon atoms.
Protein involved in the transport of electrons, a process by which electrons are transported through a series of reactions from the reductant, or electron donor, to the oxidant, or electron acceptor, with concomitant energy conversion. Necessary for both photosynthesis and aerobic respiration.
Protein involved in the synthesis of fatty acids, long chain organic acids of the general formula CH3(CnHx)COOH. They are constituents of lipids and can be saturated or unsaturated. The esterified forms are important both as energy storage molecules and structural molecules.
Protein involved in the biochemical reactions with fatty acids. Fatty acids are long chain organic acids of the general formula CH3(CnHx)COOH. They are constituents of lipids and can be saturated or unsaturated. The esterified forms are important both as energy storage molecules and structural molecules.
Protein involved in the synthesis of lipids, a diverse class of compounds which are insoluble in water but soluble in organic solvents. They include fats, oils, triacylglycerols, fatty acids, glycolipids, phospholipids and steroids.
Protein involved in the biochemical reactions of lipids. Lipids are a diverse class of compounds which are insoluble in water but soluble in organic solvents. They include fats, oils, triacylglycerols, fatty acids, glycolipids, phospholipids and steroids.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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