Martin P M, Sheridan P J
J Steroid Biochem. 1982 Feb;16(2):215-29. doi: 10.1016/0022-4731(82)90170-4.
The classical model for the mechanisms of action of steroids holds that unbound receptors for steroids reside exclusively in the cytoplasmic compartment and that they undergo translocation to the nucleus when bound to steroids in a process which is temperature sensitive. In the present study we looked at the localization of the estradiol receptor using autoradiography and biochemical procedures. Uteri from ovariectomized, and/or ovariectomized-adrenalectomized rats, as well as several cell lines [with estrogen receptors (ER+)] were incubated with [3H]-estradiol or [3H]-R2858 (methoxy-17-ethinylestradiol) for 5 min to 2 h at different concentrations of ligands (0.1-10 nM) at 4 degrees C. When the tissue or cells were processed for autoradiography the localization of steroid was nuclear and cytoplasmic. In contrast when the tissue or cells were processed using the usual biochemical procedures, all binding activity appeared in the cytosolic fraction. In addition, when concentrated preparations of homogenized uteri as well as several nuclear preparation from cell lines were made, free receptor could be demonstrated in the crude nuclear preparations. In the present study, data are presented which suggest that there are unbound receptors for estrogen in nuclei of the smooth muscle cells of myometrium as well as in nuclei of the several cell lines (ER+). We propose a new model for the distribution of estrogen receptors in which unbound receptors are in equilibrium, partitioned between nucleus and cytoplasm according to the free water content of these intracellular compartments.
类固醇作用机制的经典模型认为，类固醇的未结合受体仅存在于细胞质中，当它们与类固醇结合时会发生易位进入细胞核，这一过程对温度敏感。在本研究中，我们使用放射自显影和生化方法研究了雌二醇受体的定位。将去卵巢和/或去卵巢-肾上腺切除大鼠的子宫，以及几种细胞系[带有雌激素受体(ER+)]与[3H]-雌二醇或[3H]-R2858(甲氧基-17-乙炔基雌二醇)在4℃下，于不同浓度的配体(0.1 - 10 nM)中孵育5分钟至2小时。当对组织或细胞进行放射自显影处理时，类固醇的定位是细胞核和细胞质。相反，当使用常规生化方法处理组织或细胞时，所有结合活性都出现在胞质部分。此外，当制备子宫匀浆的浓缩制剂以及几种细胞系的核制剂时，在粗制核制剂中可以证明存在游离受体。在本研究中，所呈现的数据表明，子宫肌层平滑肌细胞核以及几种细胞系(ER+)的核中存在未结合的雌激素受体。我们提出了一种雌激素受体分布的新模型，其中未结合的受体处于平衡状态，根据这些细胞内区室的自由水含量在细胞核和细胞质之间分配。
