Cytochrome P450 2B6 is an
enzyme that in humans is encoded by the ''CYP2B6''
gene.
CYP2B6 is a member of the
cytochrome P450
Cytochromes P450 (CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are ...
group of enzymes. Along with
CYP2A6
Cytochrome P450 2A6 (abbreviated CYP2A6) is a member of the cytochrome P450 mixed-function oxidase system, which is involved in the metabolism of xenobiotics in the body. CYP2A6 is the primary enzyme responsible for the oxidation of nicotine and ...
, it is involved with metabolizing
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is used fo ...
, along with many other substances.
Function
This gene, CYP2B6, encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are
monooxygenases which catalyze many reactions involved in drug
metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the
endoplasmic reticulum
The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...
and its expression is induced by
phenobarbital. The enzyme is known to metabolize some
xenobiotics, such as the anti-cancer drugs cyclophosphamide and ifosphamide.
Gene
Transcript variants for this gene have been described; however, it has not been resolved whether these transcripts are in fact produced by this gene or by a closely related
pseudogene
Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by Reverse transcriptase, reverse transcription of an mRNA trans ...
, CYP2B7. Both the gene and the pseudogene are located in the middle of a CYP2A pseudogene found in a large cluster of cytochrome P450 genes from the CYP2A, CYP2B and CYP2F subfamilies on chromosome 19q.
CYP2B6 ligands
Following is a table of selected
substrates,
inducers and
inhibitors of CYP2B6.
Inhibitors of CYP2B6 can be classified by their
potency, such as:
*Strong inhibitor being one that causes at least a 5-fold increase in the plasma
AUC values, or more than 80% decrease in
clearance.
*Moderate inhibitor being one that causes at least a 2-fold increase in the plasma AUC values, or 50-80% decrease in clearance.
*Weak inhibitor being one that causes at least a 1.25-fold but less than 2-fold increase in the plasma AUC values, or 20-50% decrease in clearance.
References
Further reading
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External links
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