The role of adrenodoxin in adrenal steroidogenesis

During the preceding decade, major advances have been made in our understanding of the adrenal steroid hormone biosynthesis. Although the final hydroxylation steps are catalyzed by different cytochromes P450, which have been cloned and characterized in detail, the electron transferring proteins also play a pivotal role in oxygen activation and product formation. Adrenodoxin transfers electrons from adrenodoxin reductase to mitochondrial cytochromes P450. Its role in regulating adrenal steroid production has long been underestimated, and our recent understanding is mainly based on in vitro studies using bovine adrenodoxin. Although only a few reports on this topic have been published within the past 12 months, recent data have demonstrated that the concentration of adrenodoxin as well as its electron transfer and redox partner interaction properties affect steroid biosynthesis. Thorough investigation of these complex processes in different species offers the hope of improved understanding of adrenal steroid biosynthesis.