Cholesterol synthesis in rat liver peroxisomes. Conversion of mevalonic acid to cholesterol.

摘要: The key regulatory enzyme of cholesterol, dolichol, and isopentenyl adenosine biosynthesis, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) is a 97-kilodalton transmembrane glycoprotein which was believed until recently to reside exclusively in the endoplasmic reticulum mammalian cells. However, several recent publications have shown that liver cells present not only but also within peroxisomes. In an effort clarify role peroxisomal HMG-CoA reductase, highly purified (95%) rat peroxisomes from cholestyramine-treated rats were incubated with RS-[2-14C]mevalonic acid plus cytosolic proteins then tested for presence newly synthesized cholesterol. For comparison, microsomes same preparation at protein concentrations under conditions. three-step procedure employed resolve cholesterol complex mixture sterol intermediates biosynthesis. After termination reaction addition [3H]cholesterol standard, incubation products extracted separated by thin layer chromatography into number fractions. fraction containing C-27 sterols further resolved reverse-phase high pressure liquid chromatography. acetylation, silicic Confirmation identity obtained recrystallization added non-radioactive cholestenyl acetate standard. results indicate are able convert mevalonic vitro. An abstract these has been published (Krisans, S. K., Thompson, L., Burrows, R., Laub, R. J. (1986) Cell Biol. 103, 525 (abstr.).