Summary: Fatty acid desaturase
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Fatty acid desaturase Edit Wikipedia article
In the biosynthesis of essential fatty acids, different elongases alternate with desaturases (Î”6desaturase, Î”5desaturase, Î”4desaturase) repeatedly inserting an ethyl group, then forming a double bond.
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Fatty acid desaturase Provide feedback
Fatty acid desaturases are enzymes that catalyse the insertion of a double bond at the delta position of fatty acids. There seem to be two distinct families of fatty acid desaturases which do not seem to be evolutionary related: Family 1 composed of Stearoyl-CoA desaturases (SCD) [1,2] and Family 2 composed of Bacterial fatty acid desaturases, Plant stearoyl-acyl-carrier-protein desaturase  and Cyanobacterial DesA . Members of this entry are ER integral membrane proteins that share the same mushroom-shaped fold consisting of four transmembrane helices (TM1-TM4) which anchor them to the membrane, capped by a cytosolic domain containing a unique 9-10 histidine- coordinating di metal (di-iron) catalytic centre [5,6]. The structure of mouse stearoyl-CoA desaturase (SDC) revealed that TM2 and TM4 are longer than TM1 and TM3 and protrude into the cytosolic domain, providing three of the nine histidine residues that coordinate the two metal ions, while the other histidine residues are provided by the soluble domain in this enzyme .
Lindqvist Y, Huang W, Schneider G, Shanklin J; , EMBO J 1996;15:4081-4092.: Crystal structure of delta9 stearoyl-acyl carrier protein desaturase from castor seed and its relationship to other di-iron proteins. PUBMED:8861937 EPMC:8861937
Kaestner KH, Ntambi JM, Kelly TJ Jr, Lane MD;, J Biol Chem. 1989;264:14755-14761.: Differentiation-induced gene expression in 3T3-L1 preadipocytes. A second differentially expressed gene encoding stearoyl-CoA desaturase. PUBMED:2570068 EPMC:2570068
Shanklin J, Somerville C;, Proc Natl Acad Sci U S A. 1991;88:2510-2514.: Stearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs. PUBMED:2006187 EPMC:2006187
Wang H, Klein MG, Zou H, Lane W, Snell G, Levin I, Li K, Sang BC;, Nat Struct Mol Biol. 2015;22:581-585.: Crystal structure of human stearoyl-coenzyme A desaturase in complex with substrate. PUBMED:26098317 EPMC:26098317
Internal database links
|SCOOP:||7tm_1 DUF3474 Lipid_DES|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005804
Fatty acid desaturases are enzymes that catalyse the insertion of a double bond at the delta position of fatty acids. There seem to be two distinct families of fatty acid desaturases which do not seem to be evolutionary related.
Family 1 is composed of:
Family 2 is composed of:
- Bacterial fatty acid desaturases.
- Plant stearoyl-acyl-carrier-protein desaturase ( EC ) [ PUBMED:2006187 ], this enzyme catalyzes 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.
- Cyanobacterial DesA [ PUBMED:2118597 ], 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.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Biological process||lipid metabolic process (GO:0006629)|
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Families in this clan are integral membrane di-iron-containing enzymes that share the same fold consisting of four transmembrane helices (TM1-TM4) that anchor them to the endoplasmic reticulum (ER) membrane, capped by a cytosolic domain containing a unique 9-10 histidine-coordinating dimetal (di-iron) catalytic centre. This fold is found in fatty acid hydroxylases and fatty acid desaturases, which hydroxylate or desaturate lipid-based substrates in a NADH and oxygen-dependent reaction [1,2,3]. The structure of mouse stearoyl-CoA desaturase (SDC) revealed that TM2 and TM4 are longer than TM1 and TM3 and protrude into the cytosolic domain, providing three of the nine histidine residues that coordinate the two metal ions, while the other histidine residues are provided by the soluble domain in this enzyme .
The clan contains the following 3 members:FA_desaturase FA_hydroxylase Lipid_desat
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
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|Seed source:||Bateman A|
|Author:||Finn RD , Bateman A|
|Number in seed:||125|
|Number in full:||28403|
|Average length of the domain:||242.4 aa|
|Average identity of full alignment:||15 %|
|Average coverage of the sequence by the domain:||64.45 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||27|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the FA_desaturase domain has been found. There are 4 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.
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AlphaFold Structure Predictions
The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.