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The vitamin D receptor (VDR also known as the calcitriol receptor) is a member of the nuclear receptor family of transcription factors. [5] Calcitriol (the active form of vitamin D, 1,25-(OH) 2 vitamin D 3) binds to VDR, which then forms a heterodimer with the retinoid-X receptor.
Calcitriol is a hormone and the active form of vitamin D, normally made in the kidney. [ 8 ] [ 9 ] [ 10 ] It is also known as 1,25-dihydroxycholecalciferol . It binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. [ 11 ]
Vitamin D response element (VDRE) is a type of DNA sequence that is found in the promoter region of vitamin D regulated genes. This sequence binds the vitamin D receptor (VDR), when complexed with calcitriol (1,25(OH) 2 D), the active form of vitamin D, and so regulates the expression of many genes.
The active vitamin D metabolite, calcitriol, exerts its biological effects by binding to the vitamin D receptor (VDR), which is primarily located in the nuclei of target cells. [ 1 ] [ 13 ] When calcitriol binds to the VDR, it enables the receptor to act as a transcription factor , modulating the gene expression of transport proteins involved ...
However, it has been shown to have comparable affinity with calcitriol for the vitamin D receptor (VDR), while being less than 1% as active as the calcitriol in regulating calcium metabolism. The vitamin D receptor belongs to the steroid/thyroid receptor superfamily, and is found on the cells of many different tissues including the thyroid ...
25-Hydroxyvitamin D 1-alpha-hydroxylase (VD 1A hydroxylase) also known as calcidiol 1-monooxygenase [5] or cytochrome p450 27B1 (CYP27B1) or simply 1-alpha-hydroxylase is a cytochrome P450 enzyme that in humans is encoded by the CYP27B1 gene.
Calcitriol: secosteroid (1,25-dihydroxyvitamin D 3) skin/proximal tubule of kidneys: VDR: Active form of vitamin D 3. Increase absorption of calcium and phosphate from gastrointestinal tract and kidneys inhibit release of PTH. Calcidiol: secosteroid (25-hydroxyvitamin D 3) skin/proximal tubule of kidneys: VDR: Inactive form of vitamin D 3
Vitamin D requires activation by cytochrome P450 (CYP) enzymes to become active and bind to the VDR. Specifically, CYP27A1 , CYP27B1 , and CYP2R1 are involved in the activation of vitamin D, while CYP24A1 and CYP3A4 are responsible for the degradation of the active vitamin D. CYP24A1 , the primary catabolic enzyme of calcitriol , is ...