25-Hydroxyvitamin D 1-alpha-hydroxylase
25-Hydroxyvitamin D 1-alpha-hydroxylase also known as calcidiol 1-monooxygenase or cytochrome p450 27B1 or simply 1-alpha-hydroxylase is a cytochrome P450 enzyme that in humans is encoded by the CYP27B1 gene.
VD 1A hydroxylase is located in the proximal tubule of the kidney and a variety of other tissues, including skin, immune cells, and bone.
Reactions
The enzyme catalyzes the hydroxylation of calcifediol to calcitriol :The enzyme is also able to oxidize ercalcidiol to ercalcitriol, secalciferol to calcitetrol, and 25-hydroxy-24-oxocalciol to -1,25-dihydroxy-24-oxocalciol.