Phosphorylation of the 1,25-dihydroxyvitamin D3 receptor. A primary event in 1,25-dihydroxyvitamin D3 action.
1,25-Dihydroxyvitamin D3 is believed to mediate the regulation of calcium metabolism by a steroid hormone receptor mechanism. We now demonstrate that phosphorylation of the 1,25-dihydroxyvitamin D3 receptor occurs rapidly in embryonic chick duodenal organ culture in response to 1,25-dihydroxyvitamin D3. Phosphorylation of the receptor is strongly induced within 1 h by 1,25-dihydroxyvitamin D3 and occurs prior to the initiation of calcium uptake or induction of calcium-binding protein in this system. Phosphorylation is not affected by inhibition of protein synthesis by cycloheximide. Since chick duodenal organ culture is a vitamin D-responsive system that closely parallels in vivo rachitic chicken intestine, the occurrence of receptor phosphorylation in response to 1,25-dihydroxyvitamin D3 strongly suggests that it is a physiologically relevant event. In addition, since it occurs prior to the other responses to 1,25-dihydroxyvitamin D3, it appears possible that phosphorylation may play a significant role in the 1,25-dihydroxyvitamin D3 regulation of transcription in the intestine.
Brown
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TA
Department of Biochemistry, University of Wisconsin, College of Agricultural and Life Sciences, Madison 53706.
DeLuca
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HF
D000818:Animals; D002117:Calcitriol / Q000378:metabolism / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D002642:Chick Embryo; D003513:Cycloheximide / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D015854:Up-Regulation / Q000187:drug effects
D002135:Calcium-Binding Proteins; D010710:Phosphates; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D003513:Cycloheximide; D008715:Methionine; D002117:Calcitriol