Document Detail

The influence of the triglyceride content of low density lipoprotein on the interaction of apolipoprotein B-100 with cells.
MedLine Citation:
PMID:  3182816     Owner:  NLM     Status:  MEDLINE    
To study the effect of triglyceride content of low density lipoprotein (LDL) on its physicochemical and biological properties, we have depleted the triglyceride by incubation with hepatic lipase (HL-LDL) and raised the triglyceride by incubation of HL-LDL with very low density lipoprotein and lipoprotein-deficient serum. HL-LDL was taken up by human monocyte-derived macrophages and by human skin fibroblasts at an increased rate compared to untreated LDL. Incubation of the various LDL preparations revealed that cellular LDL degradation as well as LDL-mediated cholesterol esterification were inversely related to the triglyceride content of the LDL preparation. Modification of the triglyceride content of LDL also was associated with changes in the free fatty acid content, but the interaction of the LDL with cells was unaffected by the level of this component. The triglyceride content of LDL was found to be reciprocally related to the number of free lysine amino groups of LDL apolipoprotein B (apoB) which could be labeled with trinitrobenzenesulfonic acid. 13C-Nuclear magnetic resonance (NMR) spectra of native LDL and HL-LDL samples containing [13CH3]2 lysine residues formed by reductive methylation (11-13% modification) showed that the arrangement of apoB lysines is perturbed by the exposure to hepatic lipase. The ratio of labeled lysines with pK 8.9 to those with pK 10.5 exposed on the surface of LDL particles was decreased by about 40% by lipase treatment. These effects are apparently due to changes in local apoB conformation because circular dichroism spectra revealed that the average secondary structure of the entire apoB molecule is the same in native LDL and HL-LDL. The triglyceride content of LDL reciprocally affected its binding to a monoclonal antibody which recognizes epitopes around the LDL receptor binding domain of apoB. The above evidence indicates that modulation of the core triglyceride and possibly also surface phospholipid content of LDL can alter the conformation of apoB on the surface of the particle, thereby influencing the interaction with cell surface LDL receptors.
M Aviram; S Lund-Katz; M C Phillips; A Chait
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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:  263     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1988 Nov 
Date Detail:
Created Date:  1988-12-14     Completed Date:  1988-12-14     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  16842-8     Citation Subset:  IM    
Department of Medicine, University of Washington, Seattle 98195.
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MeSH Terms
Apolipoprotein B-100
Apolipoproteins B / metabolism*
Chemistry, Physical
Fatty Acids, Nonesterified / pharmacology
Fibroblasts / metabolism
Lipase / metabolism
Lipoproteins, LDL / analysis*
Liver / enzymology*
Macrophages / metabolism
Magnetic Resonance Spectroscopy
Physicochemical Phenomena
Protein Conformation
Triglycerides / analysis*
Grant Support
Reg. No./Substance:
0/Apolipoprotein B-100; 0/Apolipoproteins B; 0/Fatty Acids, Nonesterified; 0/Lipoproteins, LDL; 0/Triglycerides; EC

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