Acyl-CoA synthetase isoforms 1, 4, and 5 are present in different subcellular membranes in rat liver and can be inhibited independently

被引:233
作者
Lewin, TM
Kim, JH
Granger, DA
Vance, JE
Coleman, RA
机构
[1] Univ N Carolina, Dept Nutr, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Dept Pediat, Chapel Hill, NC 27599 USA
[3] Univ Alberta, Dept Med, Edmonton, AB T6G 2S2, Canada
[4] Univ Alberta, Canadian Inst Hlth Res, Grp Mol & Cell Biol Lipids, Edmonton, AB T6G 2S2, Canada
关键词
D O I
10.1074/jbc.M102036200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Inhibition studies have suggested that acyl-CoA synthetase (ACS, EC 6.2.1.3) isoforms might regulate the use of acyl-CoAs by different metabolic pathways. In order to determine whether the subcellular locations differed for each of the three ACSs present in liver and whether these isoforms were regulated independently, non-cross-reacting peptide antibodies were raised against ACS1, ACS4, and ACS5, ACS1 was identified in endoplasmic reticulum, mitochondria-associated membrane (MAM), and cytosol, but not in mitochondria. ACS4 was present primarily in MAM, and the 76-kDa ACS5 protein was located in mitochondrial membrane, Consistent with these locations, N-ethylmaleimide, an inhibitor of ACS4, inhibited ACS activity 47% in MAM and 28% in endoplasmic reticulum. Troglitazone, a second ACS4 inhibitor, inhibited ACS activity < 10% in microsomes and mitochondria and 45% in MAM. Triacsin C, a competitive inhibitor of both ACS1 and ACS4, inhibited ACS activity similarly in endoplasmic reticulum, MAM, and mitochondria, suggesting that a hitherto unidentified triacsin-sensitive ACS is present in mitochondria. ACS1, ACS4, and ACS5 were regulated independently by fasting and re-feeding. Fasting rats for 48 h resulted in a decrease in ACS4 protein, and an increase in ACS5, Refeeding normal chow or a high sucrose diet for 24 h after a 48-h fast increased both ACS1 and ACS4 protein expression 1.5-2.0-fold, consistent with inhibition studies, These results suggest that ACS1 and ACS4 may be linked to triacylglycerol synthesis. Taken together, the data suggest that acyl-CoAs may be functionally channeled to specific metabolic pathways through different ACS isoforms in unique subcellular locations.
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收藏
页码:24674 / 24679
页数:6
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