Serves as the first electron transfer protein in all the mitochondrial P450 systems including cholesterol side chain cleavage in all steroidogenic tissues, steroid 11-beta hydroxylation in the adrenal cortex, 25-OH-vitamin D3-24 hydroxylation in the kidney, and sterol C-27 hydroxylation in the liver. H(+) + NADP(+) + 2 reduced [adrenodoxin] = NADPH + 2 oxidized [adrenodoxin] Steroid metabolism; cholesterol metabolism. Monomer. Interacts directly with FDX1. Belongs to the ferredoxin--NADP reductase type 1 family.