Assembly and secretion of very low density lipoproteins containing apolipoprotein B48 in transfected McA-RH7777 cells - Lack of evidence that palmitoylation of apolipoprotein B48 is required for lipoprotein secretion Journal Article

  

Authors:	Vukmirica, J.; Tran, K.; Liang, X.; Shan, J.; Yuan, J.; Miskie, B. A.; Hegele, R. A.; Resh, M. D.; Yao, Z. M.
Article Title:	Assembly and secretion of very low density lipoproteins containing apolipoprotein B48 in transfected McA-RH7777 cells - Lack of evidence that palmitoylation of apolipoprotein B48 is required for lipoprotein secretion
Abstract:	We examined the role of S-linked palmitoylation of human apolipoprotein (apo) B in the assembly and secretion of very low density lipoproteins using recombinant human apoB48. There are four free cysteine residues (Cys(1085), Cys(1396), Cys(1478), and Cys(1635)) within apoB48 that potentially can be palmitoylated. All four cysteine residues were substituted with serine by site-specific mutagenesis. The mutant protein was expressed in transfected rat hepatoma McA-RH7777 cells. Metabolic labeling of the stably transfected cells with iodo-palmitic acid analog showed that the mutant apoB48 lacked palmitoylation. The lack of palmitoylation had little impact on the ability of apoB48 to assemble and secrete,very low density lipoproteins or high density lipoproteins. Immunocytochemistry experiments using confocal microscopy failed to reveal any major alterations in the intracellular distribution of the mutant apoB48 at steady state. Pulse-chase analysis combined with subcellular fractionation showed no apparent deficiency in the movement of the mutant apoB48 protein from the endoplasmic reticulum to cis/medial Golgi. However, the mutant apoB48 lacking palmitoylation showed retarded movement toward the distal Golgi and increased association (>2-fold) with the membranes of the secretory compartments. A marginal decrease (by 15-20%) in secretion efficiency as compared with that of wild type apoB48 was also observed. These results suggest that lack of palmitoylation may influence the partitioning of apoB48 between microsomal membranes and microsomal lumen, but it does not compromise the ability of apoB48 to assemble lipoproteins.
Keywords:	phosphorylation; acylation; identification; nitric-oxide synthase; caveolae; triglyceride transfer protein; b100
Journal Title:	Journal of Biological Chemistry
Volume:	278
Issue:	16
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Date Published:	2003-04-18
Start Page:	14153
End Page:	14161
Language:	English
ACCESSION:	WOS:000182405000076
DOI:	10.1074/jbc.M211995200
PROVIDER:	wos
PUBMED:	12582154
Notes:	Article -- Source: Wos

https://synapse.mskcc.org/synapse/works/has_related_data_chk/62749