title: Studies on the mechanism of action of 1 alpha, 24-dihydroxyvitamin D3. II. Specific binding of alpha, 24-dihydroxyvitamin D3 to chick intestinal receptor.
abstract: The binding of vitamin D3 analogues to the chick intestinal cytosol receptor was studied. In intestinal cytosol fraction, receptor proteins having the sedimentation constant of 2.5 S and 3.7 S to which 1 alpha,25-dihydroxyvitamin D3 binds were present, and the latter was specific for the compound. The binding of 1 alpha,24(R)-dihydroxyvitamin D3 and 1 alpha,24(S)-dihydroxyvitamin D3 to the receptor was also observed, while very weak binding was seen in the case of 24(R)25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3. The binding affinity of 1 alpha,24(R)-dihydroxyvitamin D3 to the 3.7 S receptor was 1.3 times as high as that of 1 alpha,25-dihydroxyvitamin D3, whereas those of 1 alpha,24(S)-dihydroxyvitamin D3, 1 alpha-hydroxyvitamin D3 and 25-hydroxyvitamin D3 were 10, 304 and 652 times lower than 1 alpha,25-dihydroxyvitamin D3, respectively. The dissociation constant of the receptor-1 alpha,25-dihydroxyvitamin D3 complex at 0 degrees C was 3.0 x 10(-11) M, and the dissociation constants were calculated to be 2.4 x 10(-11) M and 2.7 x 10(-10) M for the complexes with 1 alpha,24(R)-dihydroxyvitamin D3 and 1 alpha,24(S)-dihydroxyvitamin D3, respectively.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002499:Centrifugation, Density Gradient; D002645:Chickens; D003600:Cytosol / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; C023850:1 alpha,24-dihydroxyvitamin D3