9 exons. The gene sequence: 6910 bp.

1751 base pairs.

CYP2A6 is an enzyme responsible for the metabolism of clinically used pharmaceuticals such as coumarin and valproic acid, several carcinogens such as 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone and aflatoxin B1, nicotine and for the bioactivation process of tegafur to 5-FU.
The formation of 5-FU from tegafur was inhibited over 90% by a CYP2A6 selective antibody using human liver microsomes. CYP2A6 shows large interindividual and interethnic variations in its expression levels and conversion activities, which are mainly attributed to CYP2A6 genetic polymorphisms. The expression is induced by Phenobarbital and dexamethasone.

494 amino acids.

Liver.

Endoplasmic reticulum membrane, peripheral membrane protein, microsome membrane.

Oxidation, reduction, coumarin 7-hydroxylase activity, electron carrier activity, heme binding, iron ion binding, oxygen binding, the hydroxylation of the anti-cancer drugs.

Belongs to the cytochrome P450 family.

CYP2A6 shows large interindividual and interethnic variations in its expression levels and conversion activities, which are mainly attributed to CYP2A6 genetic polymorphisms. These alleles are derived from single nucleotide polymorphisms in the regulatory and coding regions, deletion mutations and conversions. Polymorphisms in the CYP2A6 gene affect enzyme activity. CYP2A6*2, a polymorphism that a single base mutation (1799T>A) cause an amino acid change from leucine at residue 160 to histidine, functionally shows no enzymatic activity in vivo and in vitro. While in Caucasian this type allele has been found in 1.1-3.0%, there is no report in Asian. CYP2A6*4C, which is a whole deleted allele for the human CYP2A6 gene, is a major mutant allele associated with decreased metabolic activity. CYP2A6*4C is relatively common in Asian populations, with estimated allele frequency of 20% in the Japanese, whereas the allele frequency is 0.5-1.0% in European. CYP2A6*7 and CYP2A6*9, a gene conversion in the 3 flanking region (6558T>C) and a point mutation in the TATA box (-48T>G), respectively, are associated with poor nicotine metabolism.
There are many alleles that have been listed by the Human CYP Allele Nomenclature Committee.