Schematic illustration of VDR mRNA and protein. The linear diagram above the protein rectangle documents an mRNA species of 4800
nucleotides that is derived from the chromosomal gene and is composed of spliced exons designated 1–9. The boundaries of these exons within
the mRNA and their corresponding locations within the VDR protein are indicated. The VDR protein is comprised of 427 aa and five general
domains, regions designated A/B, C, D, andEwhose approximate boundaries are illustrated. The shaded regions within the protein exhibit strong
homology with other members of the nuclear receptor gene family. These regions of homology include the amino-terminal DBD (C domain, gray)
and the carboxy-terminal LBD (E domain), which contains three internal regions of homology (black). Subregions E1 and AF-2 represent helices
within the E domain that participate in transactivation.