Complete cDNA sequence of a major 3-methylcholanthrene-inducible cytochrome P-450 isozyme (P-450AFB) of Syrian hamsters with high activity toward aflatoxin B1.
Cytochrome P-450AFB is major isozyme inducible by 3-methylcholanthrene in Syrian golden hamsters and shows high potency toward aflatoxin B1 activation. We have isolated and sequenced cDNA clones to P-450AFB by immunoscreening a hamster liver cDNA library in lambda gt11. The longest clone contains an open reading frame of 1482 nucleotides and encodes a protein of 494 amino acids with a molecular weight of 57,420. The sequence of P-450AFB shares a 73% and 65% homology with that of mouse P-450 15 alpha (IIA3) and rat P-450a (IIA1), respectively, indicating that P-450AFB is a unique gene of the P-450IIA subfamily. The apparent concentration of a mRNA species hybridizable to the clone as well as the concentration of a protein immunoreactive to P-450AFB was increased significantly by the treatment with 3-methyl-cholanthrene, which indicates that the increase in P-450AFB protein is due mainly to an elevation of the mRNA.
Fukuhara
M
M
Department of Pharmaceutical Sciences, Institute of Public Health, Tokyo, Japan.
Nagata
K
K
Mizokami
K
K
Yamazoe
Y
Y
Takanaka
A
A
Kato
R
R
D016604:Aflatoxin B1; D000348:Aflatoxins; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D006224:Cricetinae; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D004247:DNA / Q000302:isolation & purification*; D005796:Genes; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D008647:Mesocricetus; D008748:Methylcholanthrene; D008969:Molecular Sequence Data; D005810:Multigene Family; D012333:RNA, Messenger / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity
D000348:Aflatoxins; D007527:Isoenzymes; D012333:RNA, Messenger; D008748:Methylcholanthrene; D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D016604:Aflatoxin B1