Philpot C J, Rahman N A, Kenny N, Barisas B G, Roess D A
Department of Physiology, Colorado State University, Ft. Collins 80523, USA.
Biol Reprod. 1995 Sep;53(3):647-52. doi: 10.1095/biolreprod53.3.647.
To determine whether LH receptor rotational diffusion is similar in closely related species, we compared the rotational correlation times of LH receptors on bovine CL membranes with those of LH receptors on sheep small luteal cells and luteal cell plasma membranes using time-resolved phosphorescence anisotropy techniques. After binding of erythrosin isothiocyanate (ErITC)-derived bovine LH (bLH), ErITC-ovine LH (oLH), or ErITC-hCG, there was no difference in the initial and final anisotropy at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C, indicating that the bLH receptor was rotationally immobile on the time scale of our experiments. On these same membrane preparations, the epidermal growth factor (EGF) receptor occupied by ErITC-murine EGF exhibited temperature-dependent rotational correlation times of 80 +/- 5 microseconds, 111 +/- 7 microseconds, 254 +/- 4 microseconds, and > 1000 microseconds at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C, respectively. Slower rotational times for EGF receptor observed at higher temperatures suggested the occurrence of temperature-dependent receptor aggregation. Like the bLH receptor, the oLH receptor on intact cells and on CL plasma membranes was rotationally immobile on the time scale of our experiments when occupied by ErITC-hCG. However, the oLH-occupied receptors on small luteal cells and on luteal cell membranes had comparable rotational correlation times at 37 degrees C. These results suggest that bLH receptors are present in large, rotationally immobile structures, whereas the receptor-containing structure formed on ovine luteal cells depends on whether that receptor is occupied by hCG or oLH. Also, despite the similarities between reproductive function in these species, the LH-occupied receptor appears to be organized differently in the plasma membranes of these hormone-responsive luteal cells.
为了确定促黄体生成素（LH）受体的旋转扩散在亲缘关系密切的物种中是否相似，我们使用时间分辨磷光各向异性技术，比较了牛黄体（CL）膜上LH受体与绵羊小黄体细胞和黄体细胞质膜上LH受体的旋转相关时间。在异硫氰酸藻红蛋白（ErITC）标记的牛促黄体生成素（bLH）、ErITC标记的绵羊促黄体生成素（oLH）或ErITC标记的人绒毛膜促性腺激素（hCG）结合后，在4℃、15℃、25℃和37℃时，初始和最终各向异性没有差异，这表明在我们的实验时间尺度上，bLH受体是旋转不动的。在这些相同的膜制剂上，被ErITC标记的小鼠表皮生长因子（EGF）占据的EGF受体在4℃、15℃、25℃和37℃时分别表现出温度依赖性的旋转相关时间，分别为80±5微秒、111±7微秒、254±4微秒和>1000微秒。在较高温度下观察到EGF受体的旋转时间较慢，这表明发生了温度依赖性的受体聚集。与bLH受体一样，完整细胞和CL质膜上的oLH受体在被ErITC-hCG占据时，在我们的实验时间尺度上是旋转不动的。然而，小黄体细胞和黄体细胞膜上被oLH占据的受体在37℃时具有相当的旋转相关时间。这些结果表明，bLH受体存在于大型的、旋转不动的结构中，而在绵羊黄体细胞上形成的含受体结构取决于该受体是被hCG还是oLH占据。此外，尽管这些物种的生殖功能相似，但在这些激素反应性黄体细胞的质膜中，被LH占据的受体似乎组织方式不同。
