title: Evidence for 24,25-dihydroxycholecalciferol receptors in long bones of newborn rats.
abstract: Several reports have appeared that suggest that 24,25-dihydroxycholecalciferol has a possible biological role in bone formation. We have utilized competition studies, saturation analysis, sucrose-density-gradient sedimentation and DEAE-cellulose chromatography to demonstrate that long bones of vitamin D-depleted newborn rats contain cytoplasmic and possibly nuclear receptors that bind 24,25-dihydroxycholecalciferol with specificity and high affinity (Kd = 1.79 nM). Sucrose-density-gradient analysis of the cytoplasmic 24,25-dihydroxycholecalciferol-binding component showed a single binding macromolecule for 24,25-dihydroxycholecalciferol with a sedimentation coefficient of 3.1 S. DEAE-cellulose chromatography showed a [3H]24,25, dihydroxycholecalciferol-macromolecular complex that binds to DEAE-cellulose and elutes between 0.15 and 0.21 M-KCl. The finding of 24,25-dihydroxycholecalciferol receptors in long bones of newborn rats suggests a possible involvement of 24,25-dihydroxycholecalciferol in the metabolism of developing skeletal tissues.
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001667:Binding, Competitive; D001842:Bone and Bones / Q000378:metabolism*; D002117:Calcitriol / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002848:Chromatography, DEAE-Cellulose; D003593:Cytoplasm / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D005260:Female; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011955:Receptors, Drug / Q000378:metabolism
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D011955:Receptors, Drug; D015650:24,25-Dihydroxyvitamin D 3; D002117:Calcitriol