ApoB (apolipoprotein B)-containing lipoprotein particles, such as chylomicrons, very-low-density and low-density lipoprotein particles, transport triacylglycerol and cholesteryl esters in the bloodstream. A palmitoylation site was previously mapped to Cys-1085 in a functional truncated apoB variant (apoB-29) and abolished by mutagenesis. This Cys-1085Ser mutation resulted in secretion of smaller and denser lipoprotein particles containing 80% less cholesteryl ester and triacylglycerol than wild-type controls. We show that palmitoylation of apoB-29 occurs in the ER (endoplasmic reticulum), stimulates the ER–Golgi transport rate of apoB-29 almost 2-fold, doubles the secretion efficiency of wild-type apoB-29 in comparison with (Cys-1085Ser)apoB-29 and reduces significantly the association of wild-type apoB-29 with calnexin in comparison with (Cys-1085Ser)apoB-29. While non-palmitoylated apoB-29 co-localized extensively with constitutively secreted transferrin, wild-type apoB-29 did so only partially and was enriched in ER extensions. Our results suggest that palmitoylation of apoB regulates the biogenesis of nascent apoB-containing lipoprotein particles by concentrating apoB in a specialized ER compartment and by stimulating dissociation from constituents of the ER quality-control machinery. This reduced interaction would lead to a faster ER–Golgi transit time and a higher secretion efficiency of wild-type apoB-29. Palmitoylation could regulate the amount of apoB available for secretion of neutral lipids.
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January 2004
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Research Article|
January 01 2004
A role for palmitoylation in the quality control, assembly and secretion of apolipoprotein B
Gonzalo L. VILAS;
Gonzalo L. VILAS
Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 555 Medical Science Building, Edmonton, Alberta, Canada T6G 2H7
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Luc G. BERTHIAUME
Luc G. BERTHIAUME
1
Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 555 Medical Science Building, Edmonton, Alberta, Canada T6G 2H7
1To whom correspondence should be addressed (e-mail luc.berthiaume@ualberta.ca).
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Publisher: Portland Press Ltd
Received:
June 26 2003
Revision Received:
September 19 2003
Accepted:
September 22 2003
Accepted Manuscript online:
September 22 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2004
2004
Biochem J (2004) 377 (1): 121–130.
Article history
Received:
June 26 2003
Revision Received:
September 19 2003
Accepted:
September 22 2003
Accepted Manuscript online:
September 22 2003
Citation
Gonzalo L. VILAS, Luc G. BERTHIAUME; A role for palmitoylation in the quality control, assembly and secretion of apolipoprotein B. Biochem J 1 January 2004; 377 (1): 121–130. doi: https://doi.org/10.1042/bj20030951
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