Studies on the mechanism of action of 1 alpha,24-dihydroxyvitamin D3. III. The specific binding of 1 alpha,24-dihydroxyvitamin D3 to the receptor of chick parathyroid gland.
Three protein fractions of the cytosol of the chick parathyroid glands, which had the sedimentation constants of 2.5 S, 3.7 S and 5.5 S,  were found to bind with 1 alpha,25-dihydroxyvitamin D3. Among these proteins, the 3.7 S protein was assumed to be the specific receptor protein. The 3.7 S receptor protein was also capable of binding to 1 alpha,24-dihydroxyvitamin D3 but not 25-hydroxyvitamin D3. The binding affinity of 1 alpha,24(R)-dihydroxyvitamin D3 to the 3.7 S receptor protein was estimated to be 1.2 times greater than that of 1 alpha,25-dihydroxyvitamin D3, while 1 alpha,25-dihydroxyvitamin D3 bound to the receptor protein about 10 times stronger than 1 alpha,24(S)-dihydroxyvitamin D3. The dissociation constant for the receptor-1 alpha,25-dihydroxyvitamin D3 complex at 0 degrees C was 2.7 x 10(-11) M, the dissociation constants were calculated to be 2.2 x 10(-11) M and 2.6 x 10(-10) M for the complexes with 1 alpha,24(R)-dihydroxyvitamin D3 and 1 alpha,24(S)-dihydroxyvitamin D3.
D000818:Animals; D002499:Centrifugation, Density Gradient; D002645:Chickens; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D010280:Parathyroid Glands / Q000378:metabolism*; D018167:Receptors, Calcitriol; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011987:Receptors, Steroid
C034373:1,24-dihydroxycholecalciferol receptor; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D018167:Receptors, Calcitriol; D011956:Receptors, Cell Surface; D011987:Receptors, Steroid; C023850:1 alpha,24-dihydroxyvitamin D3