Biochemical evidence for oligomerization of rat adrenal acyl-coenzyme A:cholesterol acyltransferase.
Acyl-coenzyme A:cholesterol acyltransferase (ACAT) in rat adrenal was compared with that in rat liver. Immunoblot analyses of the microsomal fractions from adrenal with an anti-human ACAT antibody detected a 45 kDa protein. Upon pretreatment of these microsomal fractions with chemical cross-linkers such as BS3 and Sulfo-EGS, the 45 kDa band decreased with a concomitant increase in high molecular weight proteins (55, approximately 100, and approximately 230 kDa), suggesting that ACAT constitutes oligomers of 45 kDa monomers associated with a 10 kDa protein. In sharp contrast, the same immunoblot analysis of rat liver microsomal fractions identified a 50 kDa protein which was not cross-linked by these cross-linkers. Moreover, when four ACAT inhibitors were tested for their effects on adrenal and liver enzymes, NTE-122, CI-976, and E5324 were more effective for the liver enzyme, whereas 58-035 was much more effective for adrenal ACAT. These biochemical and pharmacological observations support the notion that the rat liver ACAT protein is distinct from the adrenal counterpart.
Kawasaki
T
T
Department of Biochemistry, Kumamoto University School of Medicine, Japan.
Miyazaki
A
A
Hakamata
H
H
Matsuda
H
H
Horiuchi
S
S
D000311:Adrenal Glands / Q000201:enzymology*; D000813:Anilides / Q000494:pharmacology; D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D003432:Cross-Linking Reagents; D003510:Cyclohexanes / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D046911:Macromolecular Substances; D008297:Male; D008861:Microsomes / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D008970:Molecular Weight; D010671:Phenylurea Compounds / Q000494:pharmacology; D011487:Protein Conformation; D051381:Rats; D017208:Rats, Wistar; D002785:Sterol O-Acyltransferase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D014018:Tissue Distribution
D000813:Anilides; D000814:Aniline Compounds; D003432:Cross-Linking Reagents; D003510:Cyclohexanes; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; C111531:NTE 122; D010671:Phenylurea Compounds; C069304:PD 128042; C090175:E 5324; D002785:Sterol O-Acyltransferase