title: Effect of pyridoxal 5'-phosphate on the 1,25-dihydroxyvitamin D3 receptor system.
abstract: The effect of pyridoxal 5'-phosphate on the 1,25-dihydroxyvitamin D3 receptor system has been studied by using pig intestinal chromatin. Pyridoxal 5'-phosphate did not affect the binding of 1,25-dihydroxyvitamin D3 to its receptor extracted from chromatin with hypertonic KCl, although in the presence of pyridoxal 5'-phosphate 1,25-dihydroxyvitamin D3-receptor complexes were not readily precipitated with polyethylene glycol. In contrast, pyridoxal 5'-phosphate showed a potency to dissociate the 1,25-dihydroxyvitamin D3 receptor from chromatin in a dose-dependent manner. A low concentration of pyridoxal 5'-phosphate was as effective as hypertonic KCl in dissociating the receptor from chromatin, while pyridoxine, p-nitrophenyl phosphate, or inorganic phosphate was much less effective. These observations suggest the inhibitory effect of pyridoxal 5'-phosphate on the recognition of 1,25-dihydroxyvitamin D3 by its receptor system.
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D007421:Intestine, Small / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000494:pharmacology*; D011736:Pyridoxine / Q000494:pharmacology; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000187:drug effects*; D013552:Swine
chemical_list: D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D011732:Pyridoxal Phosphate; D011736:Pyridoxine