cDNA cloning and initial characterization of CYP3A43, a novel human cytochrome P450.

Article Details

Citation

Domanski TL, Finta C, Halpert JR, Zaphiropoulos PG

cDNA cloning and initial characterization of CYP3A43, a novel human cytochrome P450.

Mol Pharmacol. 2001 Feb;59(2):386-92.

PubMed ID
11160876 [ View in PubMed
]
Abstract

The RACE amplification technology was used on a novel CYP3A-like exon 1 sequence detected during the reverse transcriptase/polymerase chain reaction analysis of human CYP3A gene expression. This resulted in the identification of cDNAs encompassing the complete coding sequence of a new member of the CYP3A gene subfamily, CYP3A43. Interestingly, the majority of the cDNAs identified were characterized by alternative splicing events such as exon skipping and complete or partial intron inclusion. CYP3A43 expression was detected in liver, kidney, pancreas, and prostate. The amino acid sequence is 75% identical to that of CYP3A4 and CYP3A5 and 71% identical to CYP3A7. CYP3A43 differs from CYP3A4 at six amino acid residues, found within the putative substrate recognition sites of CYP3A4, that are known to be determinants of substrate selectivity. The N terminus of CYP3A43 was modified for efficient expression of the protein in Escherichia coli, and a 6X histidine tag was added at the C terminus to facilitate purification. CYP3A43 gave a reduced carbon monoxide difference spectra with an absorbance maximum at 450 nm. The level of heterologous expression was significantly lower than that observed for CYP3A4 and CYP3A5. Immunoblot analyses revealed that CYP3A43 comigrates with CYP3A4 in polyacrylamide gel electrophoresis but does separate from CYP3A5. Monooxygenase assays were performed under a variety of conditions, several of which yielded reproducible, albeit low, testosterone hydroxylase activity. The findings from this study demonstrate that there is a novel CYP3A member expressed in human tissues, although its relative contribution to drug metabolism has yet to be ascertained.

DrugBank Data that Cites this Article

Drug Enzymes
DrugEnzymeKindOrganismPharmacological ActionActions
Testosterone cypionateCytochrome P450 3A43ProteinHumans
Unknown
Substrate
Details
Testosterone enanthateCytochrome P450 3A43ProteinHumans
Unknown
Substrate
Details
Testosterone undecanoateCytochrome P450 3A43ProteinHumans
Unknown
Substrate
Details
Polypeptides
NameUniProt ID
Cytochrome P450 3A43Q9HB55Details