Target type: molecularfunction
Catalysis of the reaction: calcidiol + H+ + NADPH + O2 = calcitriol + H2O + NADP+. [EC:1.14.15.18, RHEA:20573]
Calcidiol 1-monooxygenase activity is a critical enzyme in the synthesis of the active form of vitamin D, calcitriol. It catalyzes the hydroxylation of calcidiol (25-hydroxyvitamin D3) at the C1 position, transforming it into calcitriol (1,25-dihydroxyvitamin D3). This reaction occurs in the mitochondria of specific cells, primarily in the kidneys but also in other tissues like the skin, bone marrow, and immune cells. The enzyme is known as 1α-hydroxylase (CYP27B1), a member of the cytochrome P450 family. The process is tightly regulated by various factors, including parathyroid hormone, calcium levels, and phosphate levels, ensuring optimal calcitriol production. Calcitriol, the final active form of vitamin D, plays a crucial role in calcium homeostasis, bone metabolism, and immune system regulation. It exerts its effects by binding to the vitamin D receptor (VDR), a nuclear receptor, which then modulates gene expression. This action influences calcium absorption from the gut, bone resorption, and mineral homeostasis.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial | A 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial that is encoded in the genome of human. [PRO:DNx, UniProtKB:O15528] | Homo sapiens (human) |
| 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial | A 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial that is encoded in the genome of human. [PRO:DNx, UniProtKB:O15528] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| ketoconazole | 1-acetyl-4-(4-{[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy}phenyl)piperazine : A dioxolane that is 1,3-dioxolane which is substituted at positions 2, 2, and 4 by imidazol-1-ylmethyl, 2,4-dichlorophenyl, and [para-(4-acetylpiperazin-1-yl)phenoxy]methyl groups, respectively. | dichlorobenzene; dioxolane; ether; imidazoles; N-acylpiperazine; N-arylpiperazine | |
| ketoconazole | (2R,4S)-ketoconazole : A cis-1-acetyl-4-(4-{[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy}phenyl)piperazine which dioxolane moiety has (2R,4S)-configuration. | cis-1-acetyl-4-(4-{[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy}phenyl)piperazine |