The mechanism of 17 beta-estradiol uptake into prolactin-producing rat pituitary cells (GH3 cells) in culture.
The mechanism of 17 beta-estradiol uptake into prolactin-producing rat pituitary cells (GH3 cells) in culture.
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培养中产生催乳素的大鼠垂体细胞（GH3 细胞）摄取 17 β-雌二醇的机制。
DOI：
10.1210/endo-117-3-967
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发表时间：
1985
期刊：
影响因子：
4.8
通讯作者：
K. Gautvik
中科院分区：
文献类型：
--
作者：
K. Kilvik;K. Furu;E. Haug;K. Gautvik
在培养的GH 3细胞中，雌激素刺激PRL合成，GH 3细胞是来自大鼠垂体的克隆株。该模型系统用于研究17 β-雌二醇（E2）进入靶细胞的机制。在37 ℃时，[~ 3 H] E_2的细胞摄取迅速，在10-15秒内达到半最大值。在37 ℃下，在不到2分钟内观察到最大吸收。E2摄取的初始速率是细胞外激素浓度的线性函数。在完整细胞中的[3 H]E2的摄取和在不同温度下研究的结合到胞质溶胶导致线性Arrhenius图，和活化能分别为39.0和33.5 kJ mol-1度-1。纯化的GH 3细胞膜组分显示出[3 H]TRH的特异性结合位点，在无或有冷激素的情况下显示出相同的[3 H]E2的最大结合。膜结合[3 H]E2的量随温度和细胞外激素浓度的增加而线性增加。温度对E2与膜组分结合的影响逐渐发生，没有相变，并且不饱和。我们认为E2在生理温度下被靶细胞吸收的机制涉及在细胞膜中的瞬时溶解，从那里它被动地扩散到细胞中。此后，E2以能量依赖性步骤与特异性受体结合。
Estrogens stimulate PRL synthesis in cultured GH3 cells, which are clonal strains derived from the rat pituitary gland. This model system was used to study the mechanism by which 17 beta-estradiol (E2) enters target cells. The cellular uptake of [3H]E2 was rapid at 37 C and reached half-maximal values within 10-15 sec. Maximal uptake was observed in less than 2 min at 37 C. The initial rates of E2 uptake were a linear function of the extracellular hormone concentration. The uptake of [3H]E2 in intact cells and the binding to cytosol studied at different temperatures resulted in linear Arrhenius plots, and the energies of activation were 39.0 and 33.5 kJ mol-1 degree-1, respectively. Purified GH3 cells membrane fractions, which showed specific binding sites for [3H]TRH, displayed the same maximal binding of [3H]E2 in the absence or presence of cold hormone. The amount of membrane-associated [3H]E2 increased linearly with temperature and extra-cellular hormone concentration. The effect of temperature on binding of E2 to membrane fractions occurred gradually without phase transitions and was not saturable. We suggest that the mechanism by which E2 is taken up by target cells at physiological temperature involves instantaneous dissolution in the cell membrane from where it diffuses passively into the cell. E2 binds thereafter to specific receptors in an energy-dependent step.