Regulation of rat liver microsomal squalene epoxidase: inactivation of the supernatant protein factor by nucleotides.
Modulation of squalene epoxidase activity by nucleotides was studied in rat liver microsomal preparations. Supernatant protein factor (SPF) stimulates hepatic microsome-associated squalene epoxidase. The stimulatory effect of this activator was abolished by some nucleotides, and the effect of ATP on SPF was examined in detail. The inhibition by ATP was time- and concentration-dependent and was increased remarkably by the addition of Mg2+. Binding studies employing Sephadex column chromatography showed that ATP and SPF formed a complex (molar ratio, 1:1). These results suggest that nucleotides may regulate cholesterol metabolism through inactivation of the supernatant protein activator in the presence of bivalent metal ions.
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D009711:Nucleotides / Q000494:pharmacology*; D010105:Oxygenases / Q000378:metabolism*; D011506:Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D050603:Squalene Monooxygenase
D009711:Nucleotides; D011506:Proteins; D000255:Adenosine Triphosphate; D010105:Oxygenases; D050603:Squalene Monooxygenase; D008274:Magnesium