This entry includes fatty acid desaturase family members from bacteria, fungi, plants and animals. Proteins in this family contain the fatty acid desaturase domain (). The eukaryotic members, including human FADS1 and FADS2, are fusion proteins containing an N-terminal cytochrome b5-like domain and a C-terminal multiple membrane-spanning desaturase portion [].Three human fatty acid desaturase genes have been identified, fatty acid desaturase 1-3 (FADS1-3) []. FADS1 and FADS2 encode delta-5 desaturase (D5D) and delta-6 desaturase (D6D) respectively. They are membrane-bound enzymes that catalyse the rate-limiting formation of endogenous long-chain polyunsaturated fatty acid (PUFA). FADS3 is a ceramide desaturase that produces sphinga-4,14-dienine-containing ceramides (SPD ceramides). FADS3 also acts as a methyl-end fatty acyl coenzyme A (CoA) desaturase that introduces a cis double bond between the preexisting double bond and the terminal methyl group of the fatty acyl chain. [].
