CYP27B1 : cytochrome P450 family 27 subfamily B member 1
Description
The CYP27B1 (cytochrome P450 family 27 subfamily B member 1) is a protein-coding gene located on chromosome 12.
The CYP27B1 gene provides instructions for making an enzyme called 1-alpha-hydroxylase (1α-hydroxylase). This enzyme carries out the second of two reactions to convert vitamin D to its active form, 1,25-dihydroxyvitamin D3, also known as calcitriol. Vitamin D can be acquired from foods in the diet or can be made in the body with the help of sunlight exposure. When active, this vitamin is involved in maintaining the proper balance of several minerals in the body, including calcium and phosphate, which are essential for the normal formation of bones and teeth. One of vitamin D's major roles is to control the absorption of calcium and phosphate from the intestines into the bloodstream. Vitamin D is also involved in several processes unrelated to bone and tooth formation.
The CYP27B1 gene encodes for 1-alpha-hydroxylase, a cytochrome P450 monooxygenase that is essential for vitamin D metabolism and calcium and phosphorus homeostasis. This enzyme catalyzes the rate-limiting step in the activation of vitamin D in the kidney, namely the hydroxylation of 25-hydroxyvitamin D3/calcidiol at the C1alpha-position to form the hormonally active form of vitamin D3, 1alpha,25-dihydroxyvitamin D3/calcitriol. Calcitriol acts via the vitamin D receptor (VDR). CYP27B1 also has 1alpha-hydroxylase activity on vitamin D intermediates of the CYP24A1-mediated inactivation pathway, and it converts 24R,25-dihydroxyvitamin D3/secalciferol to 1-alpha,24,25-trihydroxyvitamin D3, an active ligand of VDR. CYP27B1 is also active on 25-hydroxyvitamin D2. Mechanistically, it utilizes molecular oxygen to insert one oxygen atom into a substrate and reduce the second into a water molecule, with two electrons provided by NADPH via FDXR/adrenodoxin reductase and FDX1/adrenodoxin.
CYP27B1 is also known as CP2B, CYP1, CYP1alpha, CYP27B, P450c1, PDDR, VDD1, VDDR, VDDRI, VDR.
Associated Diseases
- Hypocalcemic vitamin D-dependent rickets
- Vitamin D hydroxylation-deficient rickets, type 1A
- Multiple sclerosis
- Autoimmune Addison disease
- Vitamin D-dependent rickets
