Document Detail

Cloning, expression, and nutritional regulation of the mammalian Delta-6 desaturase.
MedLine Citation:
PMID:  9867867     Owner:  NLM     Status:  MEDLINE    
Arachidonic acid (20:4(n-6)) and docosahexaenoic acid (22:6(n-3)) have a variety of physiological functions that include being the major component of membrane phospholipid in brain and retina, substrates for eicosanoid production, and regulators of nuclear transcription factors. The rate-limiting step in the production of 20:4(n-6) and 22:6(n-3) is the desaturation of 18:2(n-6) and 18:3(n-3) by Delta-6 desaturase. In this report, we describe the cloning, characterization, and expression of a mammalian Delta-6 desaturase. The open reading frames for mouse and human Delta-6 desaturase each encode a 444-amino acid peptide, and the two peptides share an 87% amino acid homology. The amino acid sequence predicts that the peptide contains two membrane-spanning domains as well as a cytochrome b5-like domain that is characteristic of nonmammalian Delta-6 desaturases. Expression of the open reading frame in rat hepatocytes and Chinese hamster ovary cells instilled in these cells the ability to convert 18:2(n-6) and 18:3(n-3) to their respective products, 18:3(n-6) and 18:4(n-3). When mice were fed a diet containing 10% fat, hepatic enzymatic activity and mRNA abundance for hepatic Delta-6 desaturase in mice fed corn oil were 70 and 50% lower than in mice fed triolein. Finally, Northern analysis revealed that the brain contained an amount of Delta-6 desaturase mRNA that was several times greater than that found in other tissues including the liver, lung, heart, and skeletal muscle. The RNA abundance data indicate that prior conclusions regarding the low level of Delta-6 desaturase expression in nonhepatic tissues may need to be reevaluated.
H P Cho; M T Nakamura; S D Clarke
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  274     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1999 Jan 
Date Detail:
Created Date:  1999-02-05     Completed Date:  1999-02-05     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  471-7     Citation Subset:  IM    
Program of Nutritional Sciences and the Institute for Cellular and Molecular Biology, The University of Texas-Austin, Austin, Texas 78712, USA.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/AF126798;  AF126799
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MeSH Terms
Amino Acid Sequence
Arachidonic Acid / physiology*
Base Sequence
Cloning, Molecular
DNA Primers
Docosahexaenoic Acids / metabolism*
Fatty Acid Desaturases / genetics*,  metabolism
Gene Expression Regulation, Enzymologic / physiology*
Linoleoyl-CoA Desaturase
Molecular Sequence Data
RNA, Messenger / genetics,  metabolism
Sequence Homology, Amino Acid
Grant Support
Reg. No./Substance:
0/DNA Primers; 0/RNA, Messenger; 25167-62-8/Docosahexaenoic Acids; 506-32-1/Arachidonic Acid; EC 1.14.19.-/Fatty Acid Desaturases; EC Desaturase

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