title: I alpha, 25-Dihydroxyvitamin D3 receptor in the X-linked hypophosphatemic mouse.
abstract: We have attempted to determine if the resistance of the X-linked hypophosphatemic mouse to the actions of 1,25(OH)2D3 is due to abnormal cytosolic receptors for this hormone. Cytoplasmic 1,25-dihydroxy-vitamin D3 [1,25(OH)3D3] receptors were demonstrated in hypophosphatemic (HYP) mouse tissues including intestine, kidney and testis. Cytosol preparations from 14 murine tissues were prepared using hypertonic buffer and incubated for three hours at 0 C with 1,25(OH)2 [23,24(n)-(-3)H]D3 ([3H]-1,25(OH)2D3). The results of studies using 5-20% sucrose density gradients revealed th at cytosol preparations from intestine, kidney and testis exhibited a 3.2 S peak which ws specific for 1,25(OH)2D3. Scatchard analysis of intestinal, renal and testicular cytosol preparations of Hyp mice revealed a single class of noninteracting binding sites with a range of equilibrium dissociation constants (KD) of 0.9-3.5 X 10(-10) M, and a range of specific binding sites of 15-317 fmol/mg protein. There were no significant differences in values of KD, and numbers of specific binding sites among Hyp and control mice. We conclude the reported resistance of Hyp mice to vitamin D is not due to abnormal 1,24(OH)2D3 receptor in Hyp mouse.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D005260:Female; D007015:Hypophosphatemia, Familial / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*; D014960:X Chromosome
chemical_list: D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002117:Calcitriol