title: Regulation of bile acid synthesis. Isolation and characterization of microsomal phosphatases.
abstract: In preliminary experiments, we have shown that rat liver microsomes possess phosphatase activity which was inhibited in the presence of sodium fluoride. We have now separated six microsomal phosphatase fractions appearing to be isoenzymes. They all possess different kinetic constants and are not equally inhibited by tartrate and fluoride ions, inhibitors of phosphatase activity. One phosphatase fraction, in fact, is almost completely unaffected by fluoride ion. More pertinent to our interest, these isoenzymes exhibit differing abilities to modulate the activities of hydroxymethylglutaryl CoA reductase, acyl-CoA:cholesterol O-acetyltransferase, and cholesterol 7 alpha-hydroxylase. Interaction of four of the fractions with rat liver microsomes resulted in a decrease in cholesterol 7 alpha-hydroxylase activity; two were without effect.
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, PA 15261.
authors.forename: W F
authors.initials: WF
authors.lastname: Diven
authors.forename: J
authors.initials: J
authors.lastname: Sweeney
authors.forename: V
authors.initials: V
authors.lastname: Warty
authors.forename: A
authors.initials: A
authors.lastname: Sanghvi
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000096:biosynthesis*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D002785:Sterol O-Acyltransferase / Q000378:metabolism
chemical_list: D001647:Bile Acids and Salts; D007527:Isoenzymes; D006903:Hydroxymethylglutaryl CoA Reductases; D002790:Cholesterol 7-alpha-Hydroxylase; D002785:Sterol O-Acyltransferase; D010744:Phosphoric Monoester Hydrolases