Major enzyme responsible for the synthesis of 18:2 fatty acids in the endoplasmic reticulum. Contains His-rich motifs, which contribute to the interaction with the electron donor cytochrome b5. Mutations in this gene suppress the low temperature-induced phenotype of Arabidopsis tocopherol-deficient mutant vte2.
ER (microsomal) omega-6 fatty acid desaturase introduces the second double bond in the biosynthesis of 18:3 fatty acids, important constituents of plant membranes (PubMed:14593172, PubMed:7907506). Delta(12)-desaturase with regioselectivity determined by the double bond (delta(9) position) and carboxyl group of the substrate. Can use both 16:1 and 18:1 fatty acids as substrates (PubMed:8685264). It is thought to use cytochrome b5 as an electron donor and to act on fatty acids esterified to phosphatidylcholine (PC) and, possibly, other phospholipids (PubMed:14593172, PubMed:1730697, PubMed:7907506). Very low constitutive hydroxylation activity (PubMed:11864983). Required for desaturation of fatty acids present in extraplastidial membranes, including mitochondria (PubMed:11104757, PubMed:17507388). Required for salt tolerance during seed germination and early seedling growth (PubMed:22279586).