Function
Acts as a fatty acyl-coenzyme A (CoA) desaturase that introduces a cis double bond at carbon 6 of the fatty acyl chain. Involved in biosynthesis of highly unsaturated fatty acids (HUFA) from the essential polyunsaturated fatty acids (PUFA) linoleic acid (LA) (18:2n-6) and alpha-linolenic acid (ALA) (18:3n-3) precursors. 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-linoleate (GLA) (18:3n-6) and stearidonate (18:4n-3), respectively (PubMed:10049752, PubMed:14563830, PubMed:22216341, PubMed:11988075). Subsequently, in the biosynthetic pathway of HUFA n-3 series, desaturates tetracosapentaenoate (24:5n-3) to tetracosahexaenoate (24:6n-3), which is then converted to docosahexaenoate (DHA)(22:6n-3), an important lipid for nervous system function (PubMed:11988075). Also desaturates (11E)-octadecenoate (trans-vaccenoate)(18:1n-9), a metabolite in the biohydrogenation pathway of LA (18:2n-6) (PubMed:24070791).
Sequence
MGKGGNQGEGSTELQAPMPTFRWEEIQKHNLRTDRWLVIDRKVYNVTKWSQRHPGGHRVIGHYSGEDATDAFRAFHLDLDFVGKFLKPLLIGELAPEEPSLDRGKSSQITEDFRALKKTAEDMNLFKTNHLFFFLLLSHIIVMESIAWFILSYFGNGWIPTVITAFVLATSQAQAGWLQHDYGHLSVYKKSIWNHIVHKFVIGHLKGASANWWNHRHFQHHAKPNIFHKDPDIKSLHVFVLGEWQPLEYGKKKLKYLPYNHQHEYFFLIGPPLLIPMYFQYQIIMTMIRRRDWVDLAWAISYYARFFYTYIPFYGILGALVFLNFIRFLESHWFVWVTQMNHIVMEIDLDHYRDWFSSQLAATCNVEQSFFNDWFSGHLNFQIEHHLFPTMPRHNLHKIAPLVKSLCAKHGIEYQEKPLLRALLDIVSSLKKSGELWLDAYLHK