Lamberg-Allardt C, Valtonen E, Polojärvi M, Stewen P
Endocrine Research Laboratory, University of Helsinki, Finland.
Mol Cell Endocrinol. 1991 Oct;81(1-3):25-31. doi: 10.1016/0303-7207(91)90201-3.
When FRTL-5 cell cytosol was incubated with increasing amounts of [3H]1,25-dihydroxy-vitamin D3 [( 3H]1,25-(OH)2D3), saturation of specific hormone binding occurred. Scatchard analysis of specific binding of [3H]1,25-(OH)2D3 to the macromolecule yielded an apparent Kd value of 0.41 +/- 0.08 X 10(-10) M and a single maximum binding capacity of 42.8 +/- 8.8 fmol/mg protein. Sucrose gradient analysis revealed substantial [3H]1,25-(OH)2D3 association with a macromolecule sedimentating slightly faster than ovalbumin (3.7 S). [3H]1,25-(OH)2D3 was completely displaced by excess 1,25-(OH)2D3. The 1,25-(OH)2D3-receptor complex bound to DNA cellulose columns in low salt buffer, and eluted as a single peak at 0.15-0.20 M KCl. Thus, we have shown for the first time the existence of a functional 1,25-(OH)2D3 receptor in thyroid follicular cells. Furthermore, 1,25-(OH)2D3 inhibited the thyrotropin (TSH)-stimulated iodide uptake in a dose-dependent manner, indicating that 1,25-(OH)2D3 has an effect on the physiological function of rat thyroid follicular cells in culture.
当用越来越多的[3H]1,25 - 二羟基维生素D3（[3H]1,25-(OH)2D3）孵育FRTL - 5细胞胞质溶胶时，特异性激素结合出现饱和。对[3H]1,25-(OH)2D3与大分子的特异性结合进行Scatchard分析，得出表观解离常数（Kd）值为0.41±0.08×10(-10) M，单个最大结合容量为42.8±8.8 fmol/mg蛋白质。蔗糖梯度分析显示，大量的[3H]1,25-(OH)2D3与一种沉降速度略快于卵清蛋白（3.7 S）的大分子结合。[3H]1,25-(OH)2D3被过量的1,25-(OH)2D3完全取代。1,25-(OH)2D3 - 受体复合物在低盐缓冲液中与DNA纤维素柱结合，并在0.15 - 0.20 M KCl浓度下作为单一峰洗脱。因此，我们首次证明了甲状腺滤泡细胞中存在功能性1,25-(OH)2D3受体。此外，1,25-(OH)2D3以剂量依赖性方式抑制促甲状腺激素（TSH）刺激的碘摄取，表明1,25-(OH)2D3对培养的大鼠甲状腺滤泡细胞的生理功能有影响。
