The calcitriol receptor, more commonly known as the vitamin D receptor (VDR) and also known as NR1I1 (nuclear receptor subfamily 1, group I, member 1), is a member of the nuclear receptor family of transcription factors.
Calcitriol, the active form of vitamin D, binds to the VDR, which then forms a heterodimer with the retinoid-X receptor. This then binds to hormone response elements on DNA resulting in expression or transrepression of specific gene products. The VDR not only regulates transcriptional responses but also involved in microRNA-directed post transcriptional mechanisms.
In humans, the vitamin D receptor is encoded by the VDR gene.