PROSITE documentation PDOC00399Fatty acid desaturases signatures
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PURL: https://purl.expasy.org/prosite/documentation/PDOC00399
Fatty acid desaturases (EC 1.14.19.-) are enzymes that catalyze the insertion of a double bond at the delta position of fatty acids.
There seems to be two distinct families of fatty acid desaturases which do not seem to be evolutionary related.
Family 1 is composed of:
- Stearoyl-CoA desaturase (SCD) (EC 1.14.19.1) [1]. SCD is a key regulatory enzyme of unsaturated fatty acid biosynthesis. SCD introduces a cis double bond at the delta(9) position of fatty acyl-CoA's such as palmitoleoyl- and oleoyl-CoA. SCD is a membrane-bound enzyme that is thought to function as a part of a multienzyme complex in the endoplasmic reticulum of vertebrates and fungi.
As a signature pattern for this family we selected a conserved region in the C-terminal part of these enzymes, this region is rich in histidine residues and in aromatic residues.
Family 2 is composed of:
- Plants stearoyl-acyl-carrier-protein desaturase (EC 1.14.19.2) [2], these enzymes catalyze the introduction of a double bond at the delta(9) position of steraoyl-ACP to produce oleoyl-ACP. This enzyme is responsible for the conversion of saturated fatty acids to unsaturated fatty acids in the synthesis of vegetable oils.
- Cyanobacteria desA [3] an enzyme that can introduce a second cis double bond at the delta(12) position of fatty acid bound to membranes glycerolipids. DesA is involved in chilling tolerance; the phase transition temperature of lipids of cellular membranes being dependent on the degree of unsaturation of fatty acids of the membrane lipids.
As a signature pattern for this family we selected a conserved region in the C-terminal part of these enzymes.
Expert(s) to contact by email: Last update:December 2004 / Pattern and text revised.
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PROSITE methods (with tools and information) covered by this documentation:
| 1 | Authors | Kaestner K.H. Ntambi J.M. Kelly T.J. Jr. Lane M.D. |
| Title | Differentiation-induced gene expression in 3T3-L1 preadipocytes. A second differentially expressed gene encoding stearoyl-CoA desaturase. | |
| Source | J. Biol. Chem. 264:14755-14761(1989). | |
| PubMed ID | 2570068 |
| 2 | Authors | Shanklin J. Somerville C.R. |
| Title | Stearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs. | |
| Source | Proc. Natl. Acad. Sci. U.S.A. 88:2510-2514(1991). | |
| PubMed ID | 2006187 |
| 3 | Authors | Wada H. Gombos Z. Murata N. |
| Title | Enhancement of chilling tolerance of a cyanobacterium by genetic manipulation of fatty acid desaturation. | |
| Source | Nature 347:200-203(1990). | |
| PubMed ID | 2118597 | |
| DOI | 10.1038/347200a0 |
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