title: Development of 1,25-dihydroxycholecalciferol receptor in the duodenal cytosol of chick embryo.
abstract: The development of 1,25-(OH)2D3 receptor in the duodenal cytosol of chick embryo was studied by the sucrose density gradient analysis. The binding profile for 1,25-(OH)2D3 in the cytosol of vitamin D-deficient chick duodenum on the sucrose density gradient revealed 3 binding components, and the sedimentation constant was estimated as 2.5, 3.5 and 5.5S respectively. The 3.5S binding component has high affinity and low capacity for 1,25-(OH)2D3 and is thought to be 1,25-(OH)2D3 receptor. During the development of chick embryo, the 3.5S binding component was not detected in 13-day embryonic duodenum, it appeared on 15th day of incubation and then gradually increased to the level of vitamin D-deficient chick on 19th day of incubation. The 5.5S binding component was specific for 25-OH-D3 and it was found even in 13-day embryo, but it did not show any significant change during development. On the other hand, the 2.5S component was not specific for either 1,25-(OH)2D3 or 25-OH-D3. However, it was main binding component in early stages of development and decreased during development. From these results, it is suggested that the receptor for 1,25-(OH)2D3 is available a few days before hatching and the inability to produce CaBP in the duodenum of chick embryo could not be ascribed to the absence of the receptor.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002642:Chick Embryo; D002645:Chickens; D002762:Cholecalciferol / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D004386:Duodenum / Q000196:embryology* / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000378:metabolism* / Q000494:pharmacology; D011987:Receptors, Steroid / Q000378:metabolism; D014808:Vitamin D Deficiency
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D011987:Receptors, Steroid; D002762:Cholecalciferol