25-Hydroxyvitamin D 1-alpha-hydroxylase
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25-Hydroxyvitamin D 1-alpha-hydroxylase (VD 1A hydroxylase) also known as calcidiol 1-monooxygenase or cytochrome p450 27B1 (CYP27B1) 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 (keratinocytes), immune cells, and bone (osteoblasts).
Reactions
The enzyme catalyzes the hydroxylation of calcifediol to calcitriol (the bioactive form of Vitamin D):
calcidiol + 2 reduced adrenodoxin + 2 H+ + O2 ⇌ calcitriol + 2 oxidized adrenodoxin + H2O
The enzyme is also able to oxidize ercalcidiol (25-OH D2) to ercalcitriol, secalciferol to calcitetrol, and 25-hydroxy-24-oxocalciol to (1S)-1,25-dihydroxy-24-oxocalciol.
Clinical significance
Loss-of-function mutations in CYP27B1 cause Vitamin D-dependent rickets, type IA.
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
Further reading
External links
- at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Human genome location and gene details page in the UCSC Genome Browser.
- Human genome location and gene details page in the UCSC Genome Browser.