Adrenodoxin reductase

NADPH:adrenodoxin oxidoreductase, mitochondrial also known as adrenodoxin reductase is an is_associated_with::enzyme that in humans is encoded by the FDXR is_associated_with::gene, also known as ADXR. It catalyzes the following reaction:


 * NADPH + 2 oxidized adrenodoxin —→ 2 reduced adrenodoxin + NADP + H

In both bovine and human genomes there is only a single copy of this gene.

ADXR gene is expressed in all tissues that have mitochondrial P450s. The highest levels of the enzyme is found in the adrenal cortex, granulosa cells of the ovary and leydig cells of the testis that specialize in is_associated_with::steroid hormone synthesis. In addition the enzyme is also expressed in the liver, the kidney and the placenta.

Function
Adrenodoxin reductase is a mitochondrial is_associated_with::flavoprotein as it carries a is_associated_with::FAD type coenzyme. The enzyme functions as the first electron transfer protein of mitochondrial P450 systems such as is_associated_with::P450scc. The FAD coenzyme receives two electrons from NADPH and transfers them one at a time to the electron transfer protein is_associated_with::adrenodoxin. Adrenodoxin functions as a mobile shuttle that transfers electrons between ADXR and mitochondrial P450s.

Adrenodoxin reductase has been also called a is_associated_with::ferredoxin-NADP+ reductase. But, determination of the sequence and structure of the enzyme revealed that it is completely different from ferredoxin reductase.