PT  - JOURNAL ARTICLE
AU  - S A Wrighton
AU  - C Campanile
AU  - P E Thomas
AU  - S L Maines
AU  - P B Watkins
AU  - G Parker
AU  - G Mendez-Picon
AU  - M Haniu
AU  - J E Shively
AU  - W Levin
TI  - Identification of a human liver cytochrome P-450 homologous to the major isosafrole-inducible cytochrome P-450 in the rat.
DP  - 1986 Apr 01
TA  - Molecular Pharmacology
PG  - 405--410
VI  - 29
IP  - 4
4099  - http://molpharm.aspetjournals.org/content/29/4/405.short
4100  - http://molpharm.aspetjournals.org/content/29/4/405.full
SO  - Mol Pharmacol1986 Apr 01; 29
AB  - The rat 3-methylcholanthrene-inducible family of liver cytochromes P-450 contains two proteins (P-450c and P-450d) that are immunochemically related, possess 68% total sequence homology, and are induced by a number of toxic or carcinogenic compounds. To determine whether equivalent isozymes of hepatic cytochrome P-450 are expressed in humans, as they are in several mammalian species, we performed immunoblot analyses on microsomes prepared from 14 human liver specimens and found that each one contained a 52.5-kDa protein (termed HLd) that reacted with antibodies specific for rat P-450d. In addition, one specimen contained a 54-kDa protein (termed HLc) that reacted with antibodies specific for rat P-450c. HLd was purified through the use of immunoaffinity chromatography and was found to be 56% homologous to rat P-450d and 61% homologous to the equivalent isozyme in the rabbit (P-450 LM4) through their first 18 NH2-terminal amino acids. Finally, levels of immunoreactive HLd varied more than 10-fold among these patients but were unrelated to the patients' drug treatments, smoking habits, or amount of immunoreactive HLp, a human liver cytochrome P-450 related to the glucocorticoid-inducible family of rat cytochromes P-450. We conclude that, in man, there is a cytochrome P-450 family composed of two isozymes (HLc and HLd) that are immunochemically and structurally related to the 3-methylcholanthrene-inducible family observed in several other species.