Ferredoxin-1 is a small iron-sulfur protein who transfers electrons from NADPH through ferredoxin reductase to a terminal cytochrome P450. This specific oxidation/reduction system is located in steroidogenic tissues, and is involved with the synthesis of bile acid and vitamin D. FDX1 takes part in the synthesis of thyroid hormones and transfers electrons from adrenodoxin reductase to the cholesterol side chain cleavage cytochrome P450. FDX1 supports reactions catalyzed by human microsomal P450s- full length CYP17, truncated CYP17, and truncated CYP21. In addition to the FDX1 at the 11q22chromosomal locus, there are pseudogenes located on chromosomes 20 and 21 Synonyms: Adrenodoxin mitochondrial, Adrenal ferredoxin, Ferredoxin-1, Hepatoredoxin, FDX1, ADX