25-Hydroxyvitamin D3 1-alpha-hydroxylase

25-Hydroxyvitamin D3 1-alpha-hydroxylase (VD3 1A hydroxylase) also known as cytochrome p450 27B1 (CYP27B1) is a is_associated_with::cytochrome P450 is_associated_with::enzyme that in humans is encoded by the CYP27B1 is_associated_with::gene.

VD3 1A hydroxylase is located in the is_associated_with::proximal tubule of the is_associated_with::kidney and a variety of other tissues, including skin (is_associated_with::keratinocytes), immune cells, and bone (is_associated_with::osteoblasts). The is_associated_with::enzyme catalyzes the is_associated_with::hydroxylation of is_associated_with::Calcifediol to is_associated_with::calcitriol (the bioactive form of is_associated_with::Vitamin D):


 * calcidiol + NADPH + H+ + O2 $$\rightleftharpoons$$ calcitriol + NADP+ + H2O