To improve security and privacy, we are moving our web pages and services from HTTP to HTTPS.
To give users of web services time to transition to HTTPS, we will support separate HTTP and HTTPS services until the end of 2017.
From January 2018 most HTTP traffic will be automatically redirected to HTTPS. [more...]
View this page in https
PROSITE documentation PDOC00399

Fatty acid desaturases signatures


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]. 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 [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:

Piffanelli P.

Last update:

December 2004 / Pattern and text revised.

Technical section

PROSITE methods (with tools and information) covered by this documentation:

FATTY_ACID_DESATUR_1, PS00476; Fatty acid desaturases family 1 signature  (PATTERN)

FATTY_ACID_DESATUR_2, PS00574; Fatty acid desaturases family 2 signature  (PATTERN)


1AuthorsKaestner K.H., Ntambi J.M., Kelly T.J. Jr., Lane M.D.
TitleDifferentiation-induced gene expression in 3T3-L1 preadipocytes. A second differentially expressed gene encoding stearoyl-CoA desaturase.
SourceJ. Biol. Chem. 264:14755-14761(1989).
PubMed ID2570068

2AuthorsShanklin J., Somerville C.R.
TitleStearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs.
SourceProc. Natl. Acad. Sci. U.S.A. 88:2510-2514(1991).
PubMed ID2006187

3AuthorsWada H., Gombos Z., Murata N.
TitleEnhancement of chilling tolerance of a cyanobacterium by genetic manipulation of fatty acid desaturation.
SourceNature 347:200-203(1990).
PubMed ID2118597

PROSITE is copyright. It is produced by the SIB Swiss Institute Bioinformatics. There are no restrictions on its use by non-profit institutions as long as its content is in no way modified. Usage by and for commercial entities requires a license agreement. For information about the licensing scheme send an email to
Prosite License or see: prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)