Cytochrome P450 family 27 subfamily B member 1 (CYP27B1)

Cytochrome P450 family 27 subfamily B member 1 (CYP27B1) is a mitochondrial cytochrome P450 monooxygenase enzyme that catalyzes the conversion of calcifediol to calcitriol, the hormonally active form of vitamin D. This reaction is the rate-limiting step in the activation of vitamin D, which is essential for the regulation of calcium and phosphate homeostasis and thus for bone health. The enzyme is predominantly expressed in the proximal renal tubule but also found in other tissues, including bone, immune cells, and skin. Loss-of-function mutations lead to vitamin D-dependent rickets type IA, underscoring its critical role in endocrine and mineral metabolism.

Other names

25-Hydroxyvitamin D 1-alpha-hydroxylase25-Hydroxyvitamin D3 1-alpha-hydroxylaseCalcidiol 1-monooxygenase1-alpha-hydroxylaseVDDR I (Vitamin D-dependent rickets type I protein)Cytochrome P450 27B1

Hydroxylation of 25-hydroxyvitamin D3 (calcifediol) to the active form 1,25-dihydroxyvitamin D3 (calcitriol) Mitochondrial monooxygenase activity dependent on adrenodoxin as an electron transfer partner