Document Detail


Myristate exchange. A second glycosyl phosphatidylinositol myristoylation reaction in African trypanosomes.
MedLine Citation:
PMID:  7982929     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The variant surface glycoprotein of African trypanosomes has a glycosyl phosphatidylinositol (GPI) anchor that is unusual in that its fatty acids are exclusively myristate. We showed previously that the myristate is added to a free GPI in a fatty acid remodeling reaction involving deacylation and reacylation, forming glycolipid A, the anchor precursor. We now demonstrate that trypanosomes have a second pathway for GPI anchor myristoylation distinct from the fatty acid remodeling pathway, which we call "myristate exchange." This reaction involves exchange of myristate into both the sn-1 and sn-2 positions of glycolipid A, which already contain myristate. Myristoyl-CoA, the probable myristate donor in the exchange reaction, has an apparent Km of about 6 nM. We have now identified a lyso-GPI, named theta', which has myristate as its sole fatty acid; the kinetics of formation and utilization of theta' are consistent with it being an intermediate in exchange. Myristate exchange and fatty acid remodeling appear to occur in different subcellular compartments, and the two reactions have different sensitivities to inhibitors. The myristate exchange reaction may be a proofreading system to ensure that the fatty acids on variant surface glycoproteins are exclusively myristate.
Authors:
L U Buxbaum; J Raper; F R Opperdoes; P T Englund
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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:  269     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1994 Dec 
Date Detail:
Created Date:  1994-12-30     Completed Date:  1994-12-30     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  30212-20     Citation Subset:  IM    
Affiliation:
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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MeSH Terms
Descriptor/Qualifier:
Acyl Coenzyme A / metabolism
Animals
Cell Membrane / metabolism
Cell-Free System
Chromatography, Thin Layer
Glycolipids / biosynthesis,  isolation & purification
Glycosylphosphatidylinositols / isolation & purification,  metabolism*
Kinetics
Myristic Acid
Myristic Acids / metabolism*
Phospholipases A
Trypanosoma / metabolism*
Grant Support
ID/Acronym/Agency:
5T32GM07329/GM/NIGMS NIH HHS; AI 21334/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Acyl Coenzyme A; 0/Glycolipids; 0/Glycosylphosphatidylinositols; 0/Myristic Acids; 3130-72-1/S-tetradecanoyl-coenzyme A; 544-63-8/Myristic Acid; EC 3.1.1.-/Phospholipases A

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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