DNA binding property of vitamin D3 receptors associated with 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3 |
| |
| Authors: | M Inaba S Okuno A Inoue Y Nishizawa H Morii H F DeLuca |
| |
| Institution: | Second Department of Internal Medicine, Osaka City University Medical School, Japan. |
| |
| Abstract: | 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. |
| |
| Keywords: | |
|
|
