Vitamin D Nuclear Receptor (VDR)

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Ligand-binding Features Analyzed by Chemical Modification, Site-directed Mutagenisis and Homology-Extension Modeling

Rahul Ray, Narasimha Swamy
Wenrong Xu, George J. Maalouf
Scott C. Mohr

Model I

Model II

INTRODUCTION

1,25-dihydroxyvitamin D3 [1,25-(OH)2-D3] or "vitamin D hormone" plays multiple roles in the regulation of animal metabolism. These are effected in two ways: (1) at the level of the plasma membrane (by a vitamin D membrane receptor) and (2) at the level of gene transcription. This web site is dedicated to information about the key protein involved in the second process.

Domain structure of VDR

VDR has a domain structure homologous to that of the other nuclear receptors (see next section). Its 427 amino acids encompass a short N-terminal activation-function 1 (AF-1) domain (A/B), a DNA-binding domain (DBD) containing two Zn2+-fingers (C), a flexible "hinge" region (D) that includes nuclear localization signals and an HSP-70 site, and finally the ligand-binding domain (LBD or "E") whose C-terminal end also has transcriptional activation function(s) (AF-2).