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Homo sapiens Enzyme: fatty acid desaturase 2

Gene: FADS2 Accession Number: HS05918 (HumanCyc)

Synonyms: SLL0262, LLCDL2, FADSD6, TU13, DES6, D6D, Δ6 fatty acid desaturase, linoleoyl-CoA desaturase

Component of: Δ6 linoleoyl-CoA desaturase complex

Summary:
The human Δ6 desaturase is encoded by the FADS2 gene, a member of the FADS family. The gene is clustered with two more desaturase genes within 92 kb of genomic DNA on chromosome 11 [Marquardt00]. The enzyme forms a microsomal membrane-bound three-component enzyme complex that also includes cytochrome b5 and NADH-cytochrome b5 reductase 3 [Tocher].

FADS family members are considered fusion products composed of an N-terminal cytochrome b5-like domain and a C-terminal multiple membrane-spanning desaturase portion, both of which are characterized by conserved histidine motifs [Marquardt00].

The human gene has been cloned, characterized, and expressed in rat hepatocytes and Chinese hamster ovary cells, where it conferred on the cells the ability to convert 18:2(n-6) and 18:3(n-3) fatty acids to their respective products [Cho99a].

The enzyme is expressed in a wide array of tissues, highest expression is found in liver followed by brain, lung, heart, and retina [Marquardt00, Lane03].

In both fungi and animals, fatty acid desaturation generally utilize CoA-linked substrates, unlike plant enzymes, which usually desaturate the fatty acids while esterified into lipids (see γ-linolenate biosynthesis I (plants)). The enzyme catalyzes the desaturation of α-linolenoyl-CoA to stearidonoyl-CoA, linoleoyl-CoA to γ-linolenoyl-CoA [Cho99a], and also the desaturation of palmitate to the mono-unsaturated fatty acid sapienate, the most abundant fatty acid in sebum [Ge03].

Citations: [Nara02, Stohr98]

Locations: plasma membrane, endoplasmic reticulum membrane

Map Position: [63,159,476 -> 63,210,514] (46.26 centisomes) on Chromosome 11
Length: 51039 bp

Unification Links: Ensembl:ENSG00000134824 , Entrez-gene:9415 , Entrez-Nucleotide:AF084559 , Entrez-Nucleotide:AF108658 , Entrez-Nucleotide:AF126799 , Entrez-Nucleotide:AK074925 , Entrez-Nucleotide:AK074939 , Entrez-Nucleotide:AK074991 , Entrez-Nucleotide:AL050118 , Entrez-Nucleotide:BC009011 , GeneCards:FADS2 , MOPED:O95864 , OMIM:606149 , RefSeq:NM_004265 , RefSeq:NP_004256 , UCSC Human Genome:NM_004265 , UniGene:184641 , UniProt:O95864

Gene-Reaction Schematic: ?

GO Terms:

Biological Process: GO:0006636 - unsaturated fatty acid biosynthetic process
GO:0022900 - electron transport chain
Molecular Function: GO:0016491 - oxidoreductase activity
Cellular Component: GO:0005789 - endoplasmic reticulum membrane
GO:0005887 - integral component of plasma membrane

Credits:
Created 06-Aug-2008 by Caspi R , SRI International


Enzymatic reaction of: fatty acid desaturase 2

EC Number: 1.14.19.-

linoleate + a reduced electron acceptor + oxygen <=> γ-linolenate + an oxidized electron acceptor + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.


Enzymatic reaction of: fatty acid desaturase 2

EC Number: 1.14.19.-

oleate + a reduced electron acceptor + oxygen <=> linoleate + an oxidized electron acceptor + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.


Enzymatic reaction of: fatty acid desaturase 2

EC Number: 1.14.19.1

2 a ferrocytochrome b5 + stearoyl-CoA + oxygen + 2 H+ <=> 2 a ferricytochrome b5 + oleoyl-CoA + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: oleate biosynthesis


Enzymatic reaction of: Δ6 linoleoyl-CoA desaturase (fatty acid desaturase 2)

EC Number: 1.14.19.3

linoleoyl-CoA + a reduced electron acceptor + oxygen <=> γ-linolenoyl-CoA + an oxidized electron acceptor + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: γ-linolenate biosynthesis


Enzymatic reaction of: α-linolenate Δ6-desaturase (fatty acid desaturase 2)

EC Number: 1.14.19.-

α-linolenoyl-CoA + a reduced electron acceptor + oxygen <=> stearidonoyl-CoA + an oxidized electron acceptor + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: eicosapentaenoate biosynthesis

Credits:
Imported from MetaCyc 17-May-2012 by Caspi R , SRI International


Subunit of: Δ6 linoleoyl-CoA desaturase complex

Subunit composition of Δ6 linoleoyl-CoA desaturase complex = [FADS2][CYB5A][CYB5R3]
         fatty acid desaturase 2 = FADS2 (extended summary available)
         cytochrome b5 = CYB5A (summary available)
         NADH-cytochrome b5 reductase 3 = CYB5R3 (summary available)

Unification Links: MOPED:P00167 , UniProt:P00167

Credits:
Created 06-Aug-2008 by Caspi R , SRI International


Gene Local Context (not to scale): ?

Exons/Introns:


References

Cho99a: Cho HP, Nakamura MT, Clarke SD (1999). "Cloning, expression, and nutritional regulation of the mammalian Delta-6 desaturase." J Biol Chem 274(1);471-7. PMID: 9867867

Ge03: Ge L, Gordon JS, Hsuan C, Stenn K, Prouty SM (2003). "Identification of the delta-6 desaturase of human sebaceous glands: expression and enzyme activity." J Invest Dermatol 120(5);707-14. PMID: 12713571

Lane03: Lane J, Mansel RE, Jiang WG (2003). "Expression of human delta-6-desaturase is associated with aggressiveness of human breast cancer." Int J Mol Med 12(2);253-7. PMID: 12851727

Marquardt00: Marquardt A, Stohr H, White K, Weber BH (2000). "cDNA cloning, genomic structure, and chromosomal localization of three members of the human fatty acid desaturase family." Genomics 66(2);175-83. PMID: 10860662

Nara02: Nara TY, He WS, Tang C, Clarke SD, Nakamura MT (2002). "The E-box like sterol regulatory element mediates the suppression of human Delta-6 desaturase gene by highly unsaturated fatty acids." Biochem Biophys Res Commun 296(1);111-7. PMID: 12147235

Stohr98: Stohr H, Marquardt A, Rivera A, Cooper PR, Nowak NJ, Shows TB, Gerhard DS, Weber BH (1998). "A gene map of the Best's vitelliform macular dystrophy region in chromosome 11q12-q13.1." Genome Res 8(1);48-56. PMID: 9445487

Tocher: Tocher DR, Leaver MJ, Hodgson PA "Recent advances in the biochemistry and molecular biology of fatty acyl desaturases." Prog Lipid Res 37(2-3);73-117. PMID: 9829122


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of HumanCyc: Genome Biology 6(1):1-17 2004
Page generated by SRI International Pathway Tools version 18.5 on Sun Dec 21, 2014, BIOCYC13A.