Identification of the membrane anchor of microsomal rat liver cytochrome P-450.
Cytochrome P450IIB1 isolated from rat liver microsomes was incorporated into phosphatidylcholine/phosphatidylethanolamine/phosphatidylserine (10:5:1 w/w) liposomes. Trypsinolysis of proteoliposomes and sequencing of the membrane-bound domains revealed that only one peptide, comprising amino acid residues 1-21, spans the membrane. Modification of the N-terminal methionine by membrane-impermeable fluorescein isothiocyanate occurred with the protein in solution but not in proteoliposomes. We conclude that in proteoliposomes cytochrome P-450 spans the membrane only with amino acid residues 1-21, the N-terminal methionine facing the lumen.
Vergères
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Laboratorium für Biochemie, Eidgenössische Technische Hochschule, Zürich, Switzerland.
Winterhalter
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Richter
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D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D004790:Enzyme Induction; D005614:Freeze Fracturing; D008051:Lipid Bilayers; D008297:Male; D008854:Microscopy, Electron; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology; D011510:Proteolipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D008051:Lipid Bilayers; D011510:Proteolipids; C020485:proteoliposomes; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital