Ligand affinity, homodimerization, and ligand-induced secondary structural change of the human vitamin d receptor.
The intrinsic tryptophan fluorescence signal of the full-length nuclear receptor hVDR was used to directly determine the dissociation constants, K(d), of two ligands yielding K(d) = 32 nM for 1alpha,25(OH)(2)D(3) and K(d) = 322 nM for 25(OH)D(3). Ligand binding was accompanied by a conformational change in the alpha-helical part of hVDR as revealed by CD spectroscopy. In addition, the presence of calcitriol was found to be a necessary prerequisite for the homodimerisation of hVDR which was monitored using fluorescence anisotropy. We conclude that the observed ligand-induced structural change of hVDR is conditional for dimerisation of the protein.
Falsone
S F
SF
Institute of Pharmaceutical Chemistry, University of Graz, Universitätsplatz 1, Graz, A-8010, Austria.
Kurkela
R
R
Chiarandini
G
G
Vihko
P
P
Kungl
A J
AJ
D002112:Calcifediol / Q000737:chemistry / Q000494:pharmacology; D002117:Calcitriol / Q000737:chemistry; D002942:Circular Dichroism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005454:Fluorescence Polarization; D006801:Humans; D008024:Ligands; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011487:Protein Conformation / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects; D018167:Receptors, Calcitriol / Q000737:chemistry* / Q000502:physiology; D013329:Structure-Activity Relationship; D014807:Vitamin D / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology
C116441:2-methyl-1,25-dihydroxyvitamin D3; D008024:Ligands; D018167:Receptors, Calcitriol; D014807:Vitamin D; D002117:Calcitriol; D002112:Calcifediol