Vitamin D3--resistant fibroblasts have immunoassayable 1,25-dihydroxyvitamin D3 receptors.
Cultured fibroblasts obtained from patients with tissue resistance to 1,25-dihydroxyvitamin D3 (vitamin D3--dependent rickets, type II) contain normal, low, or undetectable concentrations of this hormone's receptor protein as measured by a ligand-binding assay. Extracts from these cells were evaluated for receptors by immunoassay with a recently developed monoclonal antibody to the chick receptor. The results show that a protein sedimenting at 3.7S and recognizable by the antibody exists in comparable concentrations in cells from both normal and resistant patients, irrespective of the hormone-binding abnormalities of the cells. This implies that deficiencies in hormone binding associated with inherited tissue resistance to 1,25-dihydroxyvitamin D3 probably arise from structural variations in the receptor molecule and not from defective receptor synthesis.
D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D005347:Fibroblasts / Q000032:analysis*; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000378:metabolism*; D011863:Radioimmunoassay; D011869:Radioligand Assay; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000032:analysis*; D012867:Skin / Q000166:cytology
D000911:Antibodies, Monoclonal; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid