DNA binding property of vitamin D3 receptors associated with 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3.
Using [3H]-26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3 (F6-1,25-(OH)2D3), we have examined its ability to bind to the 1,25-(OH)2D3 receptor, and the ability of the resulting complex to bind DNA. The binding sites for [3H]F6-1,25-(OH)2D3 in the chick intestinal receptor represented a limited number of saturable sites for which 1,25-(OH)2D3 competes. 1,25-Dihydroxyvitamin D3 is three times more active than F6-1,25-(OH)2D3 in displacing [3H]F6-1,25-(OH)2D3. By affinity chromatography using DNA-Sephadex, the [3H]F6-1,25-(OH)2D3 receptor complex eluted from the column in a single peak at 0.14 M KCl, while [3H]-1,25-(OH)2D3 receptor complex eluted at 0.13 M KCl. These results indicate that F6-1,25-(OH)2D3 and 1,25-(OH)2D3 recognize the same binding site of the receptor and that the F6-1,25-(OH)2D3 receptor complex binds DNA more tightly than the 1,25-(OH)2D3 receptor complex. We suggest that the higher binding affinity for DNA may contribute to the greater biological activity of F6-1,25-(OH)2D3.
Inaba
M
M
Second Department of Internal Medicine, Osaka City University Medical School, Japan.
Okuno
S
S
Inoue
A
A
Nishizawa
Y
Y
Morii
H
H
DeLuca
H F
HF
D000818:Animals; D001667:Binding, Competitive; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000378:metabolism; D002645:Chickens; D002762:Cholecalciferol / Q000378:metabolism*; D002846:Chromatography, Affinity / Q000379:methods; D004247:DNA; D003911:Dextrans; D007413:Intestinal Mucosa / Q000378:metabolism; D007700:Kinetics; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000302:isolation & purification / Q000378:metabolism*; D005466:Fluorocarbons
D002117:Calcitriol; D002762:Cholecalciferol; D004247:DNA; D003911:Dextrans; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; C058171:DNA-Sephadex; C040488:26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3; D005466:Fluorocarbons