Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute cannabidiol treatment of mice inactivated hepatic microsomal cytochrome P-450IIIA (P-450IIIA) and markedly inhibited in vitro cannabinoid metabolism. Antibodies raised against purified P-450IIIA inhibited the microsomal formation of quantitatively minor cannabinoid metabolites but had no effect on the major metabolites. Cannabinoid hydroxylation to the major metabolites was used as a functional probe to isolate and purify a P-450 (termed P-450THC) from hepatic microsomes of untreated mice. The purified protein had an apparent molecular weight of 47,000 and a specific content of 15.4 nmol/mg and exhibited an absorbance maximum at 452 nm for the reduced carbon monoxide complex. NH2-terminal sequence analysis of the first 16 residues of P-450THC suggests that it is a member of the P-450IIC subfamily, because its sequence is 85 and 69% identical to published sequences of rat hepatic P-450IIC7 and P-450IIC6, respectively. P-450THC exhibited high activity for cannabinoid hydroxylation and specifically produced 6 alpha- and 7-hydroxy-delta 1-tetrahydrocannabinol, as well as 6 alpha-, 7-, and 4"-hydroxycannabidiol. Unlike anti-P-450IIIA antibody, antibody raised against purified P-450THC markedly inhibited the microsomal formation of all major cannabinoid metabolites. Similar immunoinhibition studies also revealed the existence of orthologs of mouse P-450THC and P-450IIIA in human liver microsomes. Thus, cannabidiol treatment of mice resulted in the inactivation of at least two constitutive P-450 isozymes, which together account for the majority of the detected cannabinoid metabolites.
Mol Pharmacol 1991 Aug
PMID:Purification and characterization of the major hepatic cannabinoid hydroxylase in the mouse: a possible member of the cytochrome P-450IIC subfamily. 187 10

The nuclear yeast mutant pet ts2858 is defective in the removal of pre-sequences from the mitochondrially encoded cytochrome oxidase subunit II (COXII) and the processing intermediate of cytochrome b2 (Cytb2), a nuclear gene product. In order to identify the genetic lesion in this mutant we have cloned and characterized a DNA region which complements the pet ts2858 mutation. The DNA sequence revealed three open reading frames, one of which is responsible for the complementation. A 570 bp reading frame represents the structural gene PET2858, as demonstrated by in vitro mutagenesis, gene expression from a foreign promoter, and allelism tests. PET2858 encodes a 21.4 kDa protein, which is essential for growth on non-fermentable carbon sources and for the proteolytic processing of COXII and the Cytb2 intermediate. When the N-terminus of the PET2858 protein is fused to a reporter protein, the resulting hybrid molecule is imported into mitochondria. Interestingly, the N-terminal half of the deduced PET2858 protein exhibits 30.7% amino acid identity to the leader peptidase of Escherichia coli. These results suggest that PET2858 codes for a mitochondrial inner membrane protease (IMP1) or at least a subunit of it. This protease is involved in protein processing and export from the mitochondrial matrix.
Mol Gen Genet 1991 Aug
PMID:Mitochondrial inner membrane protease 1 of Saccharomyces cerevisiae shows sequence similarity to the Escherichia coli leader peptidase. 188 6

Ascorbic acid (VC) deficiency resulted in a decrease in the activities of aminopyrine N-demethylase, aniline hydroxylase, and p-nitroanisole O-demethylase and in the content of cytochrome P-450, as spectrally determined, whereas it caused an increase in the activities of 6 beta-hydroxylases for testosterone and progesterone in liver microsomes of guinea pigs. Western blot analysis of liver microsomes with antibodies to rat P-448-H (P-4501A2), P-450j (P-450IIE), P-450 PB-1 (P-450IIIA), and P-450b (P-450IIB1) showed that VC deficiency decreased the amount of cytochrome P-450 immunochemically related to P-450IA2 and P-450IIE but did not change the amount of the form that was cross-reactive with antibodies to P-450IIB1 and tended to slightly increase (not statistically significantly) the amount of the form of the cytochrome immunochemically related to P-450IIIA. The larger decrease by VC deficiency in the amount of cytochrome P-450 that was cross-reactive to the rat P-450IA2 resulted in a lower capacity of liver microsomes to activate promutagens, such as 2-amino-3-methyl-imidazo(4,5-f)quinoline and aflatoxin B1. These results indicate that VC deficiency in guinea pigs differentially affects the content of individual forms of cytochrome P-450.
Mol Pharmacol 1991 Apr
PMID:Ascorbic acid deficiency decreases specific forms of cytochrome P-450 in liver microsomes of guinea pigs. 190 38

The alcohol-inducible CYP2E subfamily in rabbits contains two genes; CYP2E1 encodes the cytochrome earlier termed P-450 3a, and CYP2E2 encodes a cytochrome that is 97% identical in amino acid sequence to cytochrome P-450 (P-450) 2E1. In the present studies, the ontogenic expression of these two cytochromes was examined. In liver, P-450 2E2 mRNA is detectable immediately after birth and reaches slightly greater than the adult level at 2 weeks of age; in contrast, P-450 2E1 mRNA is not detectable until day 14 and increases rapidly to approximately twice the adult level at 5 weeks of age. P-450 2E protein is present in liver immediately after birth, coincident with the appearance of P-450 2E2 mRNA, peaks at 2 weeks, and then, despite the continued elevation in P-450 2E mRNA, decreases to the adult level at 5 weeks. In kidney, P-450 2E2 mRNA is not detectable at any age; P-450 2E1 mRNA, however, is present at 1 week, and the level increases to about half the adult level at 5 weeks of age. P-450 2E protein in this tissue is elevated at 2 weeks, relative to mRNA levels, and reaches approximately half the adult level at 5 weeks. The lack of close correlation between mRNA and protein levels in the liver and kidney of newborn rabbits indicates that the posttranscriptional control of P-450 2E enzyme levels that predominates in adult animals is also operative during the neonatal period. Monooxygenase activities with ethanol and p-nitrophenol as substrates reflect the developmental increase in P-450 2E protein, as well as the appearance and levels of spectrally detectable P-450, cytochrome b5, and NADPH-P-450 reductase in hepatic microsomes. The expression of P-450 2E2, but not P-450 2E1, in early neonates suggests that these two closely related cytochromes may have functional differences that are important during the first few weeks of life.
Mol Pharmacol 1991 Jul
PMID:Differences in the developmental expression of rabbit cytochromes P-450 2E1 and 2E2. 190 76

We transduced mouse cytochrome P4501A2 DNA into NIH 3T3 cells by retrovirus-mediated gene transfer. The capacity of the transduced cytochrome P4501A2 for metabolic activation and DNA-carcinogen adduct formation of aromatic amine carcinogens was investigated. Clones of NIH 3T3 cells that constitutively express cytochrome P4501A2 and controls were exposed to a prototype food-derived carcinogenic heterocyclic amine, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and an aromatic amine, 2-acetylaminofluorene (AAF), and their genomic DNAs were analyzed for adducts by 32P-postlabeling assays. Kinetic analysis of DNA-carcinogen adducts indicated that adduct formation was dependent on the level of the enzyme, the dose of carcinogen, and the duration of exposure. Addition of 7,8-benzoflavone, an inhibitor of P4501A2, blocked both the enzyme activity and DNA-adduct formation, indicating the specific role of P4501A2 in metabolic activation and adduct formation. Three specific IQ-DNA adducts were detected in cells expressing P4501A2. Fingerprints of the in situ DNA adducts were similar to those of the in vivo adducts in rodent hepatic DNA after the administration of IQ. A single AAF-DNA adduct was observed in cells exposed to AAF, but other minor adducts were also detected in vivo. These results show that cells expressing constitutive levels of single cytochrome P450s provide an excellent in situ model system for analyzing the catalytic specificity, metabolic activation, and genotoxicity of putative toxic, mutagenic, and carcinogenic substances.
Mol Carcinog 1991
PMID:Cytochrome P4501A2 constitutively expressed from transduced DNA mediates metabolic activation and DNA-adduct formation of aromatic amine carcinogens in NIH 3T3 cells. 191 Apr 84

A hybridization probe that is homologous to the B2 short interspersed repetitive element detects an mRNA in mouse kidney and liver that is regulated by androgen. Administration of testosterone induces this mRNA in kidney and represses it in liver. The mRNA was cloned by first using the B2 probe to select 48 cDNA clones from an androgen-induced kidney library. These clones were then tested for their androgen response by hybridizing them with probes made by reverse transcription of basal and testosterone-treated kidney poly(A)+ RNA. Any homology to the B2 sequence was masked by prehybridizing the filters to an excess of non-radioactive RNA synthesized from a B2 sequence cloned into a riboprobe vector. A unique sequence was subcloned from the largest androgen-responsive cDNA clone. A radioactive riboprobe generated from the unique sequence subclone detected an androgen-responsive mRNA in Northern blots with the same electrophoretic mobility as the predominant androgen-responsive mRNA detected with the B2 homologous riboprobe. The riboprobe also detected a unique sequence in Southern blots of genomic DNA. This subclone was then used as the probe to isolate a full-length cDNA clone from a second androgen-induced kidney library. When sequenced, this full-length cDNA of an androgen-responsive, B2-containing mRNA showed strong homology to the rat and human cytochrome P450J and the rabbit cytochrome P450 3a genes (CYP2E1). It showed only weak homology to the mouse testosterone 15 alpha-hydroxylase gene (CYP2A3) which is also regulated reciprocally by androgen in kidney and liver. The sequence of mouse P450J is identical to the B2 homologous mRNA previously named B2+ mRNAx which is abundant in mouse liver.
J Mol Endocrinol 1991 Oct
PMID:Isolation of the mouse cytochrome P450J (CYP2E1) cDNA and its reciprocal testosterone regulation in kidney and liver. 193 Jun 27

The ability of 3,3',4,4'-tetrachlorobiphenyl to stimulate bilirubin degradation by liver microsomes from rats treated with a polycyclic aromatic hydrocarbon-type inducer has been confirmed and extended to another planar biphenyl, 3,3',4,4',5,5'-hexachlorobiphenyl. The following evidence indicates the involvement of an inducible cytochrome P450 isoenzyme in this reaction, with a role, specifically, for cytochrome P450IA1. (a) The biphenyl-dependent bilirubin degradation and 7-ethoxyresorufin O-deethylase (EROD) activity were both markedly inhibited by a monoclonal antibody raised against cytochrome P450IA1; the two dose-inhibition curves were essentially superimposable, with maximum inhibition observed for both activities at a ratio of antibody to total cytochrome P450 of about 1. (b) Treatment of rats with 3-methylcholanthrene increased both EROD activity and biphenyl-dependent bilirubin degradation not only in the liver (where both cytochromes P450IA1 and P450IA2 are inducible) but also in the kidney (where only induction of cytochrome P450IA1 has been reported), with similar ratios of the two enzymatic activities in both tissues. (c) With carbon tetrachloride and 3,5-diethoxycarbonyl-4-ethyl-1,4-dihydro-2,4-dimethyl pyridine as selective suicide substrates of members of the cytochrome P450IA subfamily, the biphenyl-dependent degradation of bilirubin showed a good correlation with cytochrome P450IA1, determined both as EROD activity and as an immunoreactive band on immunoblotting. These findings implicate cytochrome P450IA1 in the alternative pathway of bilirubin disposal, which can be stimulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin in Gunn rats, and also help substantiate the hypothesis that interaction of a polyhalogenated aromatic compound with the induced cytochrome may initiate an oxidative mechanism leading to oxidation of target molecules in the cell, one of which is bilirubin.
Mol Pharmacol 1991 Nov
PMID:Inducible bilirubin-degrading system of rat liver microsomes: role of cytochrome P450IA1. 194 39

Steroid 17 alpha-hydroxylase has emerged as a key enzyme in steroidogenic cells: (i) it represents the branch point between the 17-deoxy (mineralo) and the 17-hydroxy (gluco) corticosteroid pathways in the adrenal cortex; (ii) the corresponding specific cytochrome (P-450(17 alpha] is highly dependent upon hormonal regulation; and (iii) the enzyme also catalyzes the steroid 17-20 lyase reaction, leading to the major androgens in the testis. As a prerequisite to the study of its regulation in intact cell, 17 alpha-hydroxylase was purified from calf testis microsomal preparations. Following five chromatographic steps, the enzyme was obtained as an apparently homogeneous protein of Mr = 57 kDa upon gel electrophoresis. The procedure yielded a recovery of about 10% as judged by cytochrome P-450 assay. Whereas 17 alpha-hydroxylase specific activity was about 30-fold enriched during the purification, that of the C17-20 lyase was increased by about 6-fold, strongly suggesting that its organelle environment may modulate the enzymatic activity. The purified enzyme yielded a 20 N-terminal amino-acid sequence showing a complete homology with that of its adrenal counterpart and a polyclonal antibody raised against our preparation revealed a 57 kDa protein band in bovine adrenocortical microsomal extracts, upon immunoblotting experiments. It was thus concluded that bovine 17 alpha-hydroxylase activity is supported by highly similar if not identical enzymatic proteins in both testis and adrenal cortex tissues. The purified P-450(17 alpha) preparation is now being used in reconstitution experiments which suggest that microsomal components may contribute to a different expression of the enzyme specificity in its native testis or adrenocortical intracellular environment, respectively.
J Steroid Biochem Mol Biol 1991
PMID:Purification and properties of steroid 17 alpha-hydroxylase from calf testis. 195 44

Further genetic evidence is provided here that Bradyrhizobium japonicum possesses a mitochondria-like electron-transport pathway: 2[H]----UQ----bc1----c----aa3----O2. Two Tn5-induced mutants, COX122 and COX132, having cytochrome c oxidase-negative phenotypes, were obtained and characterized. Mutant COX122 was defective in a novel gene, named cycM, which was responsible for the synthesis of a c-type cytochrome with an Mr of 20,000 (20K). This 20K cytochrome c appeared to catalyse electron transport from the cytochrome bc1 complex to the aa3-type terminal oxidase and, unlike mitochondrial cytochrome c, was membrane-bound in B. japonicum. The Tn5 insertion of mutant COX132 was localized in coxA, the structural gene for subunit I of cytochrome aa3. This finding also led to the cloning and sequencing of the corresponding wild-type coxA gene that encoded a 541-amino-acid protein with a predicted Mr of 59,247. The CoxA protein shared about 60% sequence identity with the cytochrome aa3 subunit I of mitochondria. The B. japonicum cycM and coxA mutants were able to fix nitrogen in symbiosis with soybean (Fix+). In contrast, mutants described previously which lacked the bc1 complex did not develop into endosymbiotic bacteroids and were thus Fix-. The data suggest that a symbiosis-specific respiratory chain exists in B. japonicum in which the electrons branch off at the bc1 complex.
Mol Microbiol 1990 Dec
PMID:Genetic analysis of the cytochrome c-aa3 branch of the Bradyrhizobium japonicum respiratory chain. 196 17

Microsomes prepared from livers of male and female rats of nine inbred and outbred strains and of male Sprague-Dawley rats pretreated with monooxygenase-inducing agents were used to study N-dealkylation of diazepam and temazepam and C3-hydroxylation of diazepam and nordazepam. Both C3-hydroxylation reactions were more rapid in male than in female liver preparations, but this gender-dependent pattern was not seen with the N-dealkylation reactions. These results indicate the lack of identity of the monooxygenases responsible for the two kinds of reaction and suggest that male-specific enzyme(s) are responsible for the C3-hydroxylations. Induction studies were undertaken to further define these enzymes. To do this, liver microsomes prepared from male Sprague-Dawley rats pretreated with a variety of agents known to have different monooxygenase induction effects were used. With triacetyloleandomycin, dexamethasone, and phenobarbital pretreatment, the specific activities of the C3-hydroxylation reactions were selectively elevated over corresponding control values. These particular xenobiotics are known to enhance the abundance of cytochrome P450IIIA family enzymes, and our results strongly suggest the involvement of these enzymes in the benzodiazepine B ring monooxygenations. Formation of temazepam was also shown to be inhibited by triacetyloleandomycin. This effect was demonstrated to be equal in both saline-treated and dexamethasone-treated male Sprague-Dawley rat liver microsomes, with the antibiotic present either with diazepam throughout the entire incubation period or initially with NADPH in a preincubation mix for 15 min, following which C3-hydroxylation was initiated by the addition of diazepam. These results confirm the uniformity of the involvement of cytochrome P450IIIA family enzymes in diazepam C3-hydroxylation in untreated and inducer-treated rat liver microsomes. Recent studies with human and rabbit liver microsomal preparations have shown that orthologues of these enzymes also catalyze an equivalent hydroxylation in the B ring of midazolam. These findings, considered with the present results showing that the adjacent methyl N-substituent (absent in nordazepam but present in diazepam) did not affect the selectivity of these enzymes for the C3-hydroxylation reaction, suggest that neither steric nor electronic factors markedly influence catalysis of this monooxygenation by these enzymes.
Mol Pharmacol 1990 May
PMID:Cytochrome P450IIIA enzymes in rat liver microsomes: involvement in C3-hydroxylation of diazepam and nordazepam but not N-dealkylation of diazepam and temazepam. 197 Oct 91


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