Target type: molecularfunction
Catalysis of the hydroxylation of C-24 of 25-hydroxycholecalciferol (25-hydroxyvitamin D3) to form 24(R),25-dihydroxycholecalciferol. [ISBN:0471331309]
25-Hydroxycholecalciferol-24-hydroxylase (CYP24A1) is a cytochrome P450 enzyme that catalyzes the 24-hydroxylation of 25-hydroxyvitamin D3, the main circulating form of vitamin D. This reaction is the primary pathway for the inactivation of vitamin D, preventing excessive levels of the hormone in the body.
The enzyme acts by introducing a hydroxyl group at the C24 position of 25-hydroxyvitamin D3, converting it to 24,25-dihydroxyvitamin D3, also known as calcifediol. Calcifediol is less biologically active than 25-hydroxyvitamin D3 and is further metabolized to inactive products in the kidneys.
The regulation of CYP24A1 activity is crucial for maintaining adequate levels of vitamin D and preventing hypercalcemia. It is tightly regulated by both vitamin D levels and parathyroid hormone (PTH). High levels of vitamin D or PTH stimulate CYP24A1 expression and activity, leading to increased inactivation of vitamin D. Conversely, low levels of vitamin D or PTH suppress CYP24A1 activity, allowing for accumulation of active vitamin D.
The function of CYP24A1 is vital for maintaining calcium homeostasis. By controlling the levels of active vitamin D, it regulates calcium absorption in the gut, bone metabolism, and renal calcium reabsorption. Dysregulation of CYP24A1 activity can contribute to various conditions, including vitamin D deficiency, hypercalcemia, and bone disorders.'
"
| Protein | Definition | Taxonomy |
|---|---|---|
| 1,25-dihydroxyvitamin D(3) 24-hydroxylase, mitochondrial | A 1,25-dihydroxyvitamin D(3) 24-hydroxylase, mitochondrial that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q07973] | 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 | |
| liarozole | liarozole: inhibits all-trans-retinoic acid 4-hydroxylase; effective against hormone-dependent and hormone-independent tumors; R 75251 is chlorohydrate of R 61405; a potent inhibitor of retinoic acid metabolism; USAN name - liarozole fumarate | benzimidazoles | |
| 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 | |
| calcitriol | dihydroxy-vitamin D3: as a major in vitro metabolite of 1alpha,25-dihydroxyvitamin D3, produced in primary cultures of neonatal human keratinocytes | D3 vitamins; hydroxycalciol; triol | antineoplastic agent; antipsoriatic; bone density conservation agent; calcium channel agonist; calcium channel modulator; hormone; human metabolite; immunomodulator; metabolite; mouse metabolite; nutraceutical |