vitamin D binding

Definition

Target type: molecularfunction

Binding to vitamin D, any of a group of related, fat-soluble compounds that are derived from delta-5,7 steroids and play a central role in calcium metabolism. Specific forms of vitamin D include calciferol (ergocalciferol; vitamin D2) and cholecalciferol (calciol; vitamin D3). [GOC:mah, ISBN:0471331309]

Vitamin D binding involves the interaction of vitamin D metabolites, primarily calcitriol (1,25-dihydroxyvitamin D3), with specific proteins known as vitamin D receptors (VDRs). VDRs belong to the nuclear receptor superfamily and act as ligand-activated transcription factors. Upon binding to calcitriol, VDR undergoes a conformational change, dimerizes with the retinoid X receptor (RXR), and translocates to the nucleus. In the nucleus, the VDR-RXR heterodimer binds to specific DNA sequences called vitamin D response elements (VDREs) located in the promoter regions of target genes. This binding event triggers the recruitment of coactivator proteins, leading to the activation of gene transcription.

The molecular function of vitamin D binding can be summarized as follows:

1. **Ligand binding:** Vitamin D metabolites, particularly calcitriol, bind to VDR with high affinity.

2. **Conformational change:** Binding of calcitriol induces a conformational change in VDR, enabling it to dimerize with RXR.

3. **Nuclear translocation:** The VDR-RXR heterodimer translocates to the nucleus.

4. **DNA binding:** The VDR-RXR complex binds to VDREs in the promoter regions of target genes.

5. **Transcriptional activation:** Binding to VDREs recruits coactivator proteins, leading to the activation of target gene transcription.

The transcriptional activation of target genes by VDR-mediated vitamin D binding plays a crucial role in various biological processes, including calcium and phosphate homeostasis, bone metabolism, immune regulation, cell proliferation, and differentiation.'
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Proteins (1)

Compounds (1)