Secondary structure prediction of liver microsomal cytochrome P-450; proposed model of spatial arrangement in a membrane.
The secondary structure of rabbit liver microsomal cytochrome P-450 LM2, rat liver microsomal cytochromes P-450b and P-450e (phenobarbital-inducible), and rat liver microsomal cytochromes P-450c, P-450d (3-methylcholanthrene-inducible) was predicted by a combination of methods (i) identifying the transmembrane parts of integral membrane proteins, and (ii) statistically predicting the secondary structure of globular proteins. The results are similar for all phenobarbital-inducible enzymes and make it possible to construct two structural models with seven or four transmembrane alpha-helices. The cytochromes of the second group obviously form a second structural family with four membrane-spanning alpha-helices. In both cases, a large ectodomain with several consecutive alpha-helices, which may provide the heme-binding pocket, is exposed out of the membrane.
Hudecek
J
J
Department of Biochemistry, Charles University, Prague, Czechoslovakia.
Anzenbacher
P
P
D000465:Algorithms; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis; D004790:Enzyme Induction; D007527:Isoenzymes; D008566:Membranes / Q000201:enzymology; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D008956:Models, Chemical; D010634:Phenobarbital / Q000494:pharmacology; D011487:Protein Conformation; D011817:Rabbits
D007527:Isoenzymes; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital