The role of the membrane domain in the regulated degradation of 3-hydroxy-3-methylglutaryl coenzyme A reductase.

摘要: We have constructed a series of mutations in the membrane and linker domains Syrian hamster 3-hydroxy-3-methylglutaryl-(HMG) CoA reductase order to determine regions critical for regulated degradation enzyme. In transfected Chinese ovary cells, we expressed fusion protein, HMGal, which consists HMG-CoA fused beta-galactosidase. Using this determined that deletion 64 amino acids from central region domain causes protein be degraded extremely rapidly. addition, PEST sequences has little effect on degradation, but makes protein's insensitive sterols mevalonate. addition mutations, systematically replaced each hydrophobic, putative spanning with first transmembrane sequence bacteriorhodopsin. Replacement span 4 no degradation. Replacements spans 5 or 6 result normal basal rate is not accelerated by mevalonate, low density lipoprotein, 25-hydroxycholesterol. 3 results whose similarly since might mislocalized, these are inconclusive. 7 yields short-lived more rapidly response mevalonate exogenous sterols. 8 extends both mevalonate-accelerated half-life about 5-fold. This work begins define within reductase.