Robinson M S, Rhodes J A, Albertini D F
J Cell Physiol. 1983 Oct;117(1):43-50. doi: 10.1002/jcp.1041170108.
Kinetic studies were performed on two-day cultures of rat ovarian granulosa cells to follow the fate of surface-bound 125I-labeled human chorionic gonadotropin (125I-hCG). Low pH was used to release hCG from its surface receptor, allowing us to distinguish between surface-bound and internalized hormone. Because our results indicated that hormone is lost from the cell surface by dissociation as well as internalization, equations were derived to determine independent rate constants for each process. We calculate that if hormone binding were irreversible, the t 1/2 for internalization would be 8.5 hour. Morphometric studies on the uptake of horseradish peroxidase indicate that the t 1/2 for internalization of bulk membrane in granulosa cells is 55 to 77 minutes. Thus, the rate of uptake of surface-bound hCG appears to be seven to nine times slower than the rate of uptake of bulk plasma membrane, which suggests that the LH/hCG receptor may be selectively excluded from the endocytic vesicles of granulosa cells.
对大鼠卵巢颗粒细胞进行了为期两天的培养动力学研究，以追踪表面结合的125I标记人绒毛膜促性腺激素（125I-hCG）的去向。采用低pH值从其表面受体释放hCG，从而使我们能够区分表面结合的激素和内化的激素。由于我们的结果表明激素通过解离和内化从细胞表面丢失，因此推导了方程式以确定每个过程的独立速率常数。我们计算得出，如果激素结合是不可逆的，内化的t1/2将为8.5小时。对辣根过氧化物酶摄取的形态计量学研究表明，颗粒细胞中大量细胞膜内化的t1/2为55至77分钟。因此，表面结合的hCG的摄取速率似乎比大量质膜的摄取速率慢七至九倍，这表明LH/hCG受体可能被选择性地排除在颗粒细胞的内吞小泡之外。
