Module 7: Figure vitamin D receptor activation
Vitamin D receptor activation.
The activation of the vitamin D receptor (VDR) begins with the binding of the vitamin D3 hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and this is followed by its phosphorylation by protein kinase C and casein kinase II that then induces a conformational change enabling it to bind its partner retinoid X receptor (RXR). The VDR/RXR heterodimer then binds to the vitamin D response element (VDRE). Once in place, the complex binds to a number of co-activators enabling the transcriptional complex to activate RNA polymerase II (Pol II) to initiate the expression of a large number of genes that encode proteins that function in a number of cellular processes.