Müller R E, Beebe D M, Bercel E, Traish A M, Wotiz H H
J Steroid Biochem. 1984 Apr;20(4B):1039-46. doi: 10.1016/0022-4731(84)90016-5.
The cytosolic estrogen receptor (calf uterus) bound to estradiol (E2) at 0 degrees C changes from a state with fast into a state with slow E2 dissociation rates when placed at 28 degrees C. This temperature accelerated transition in receptor affinity for its ligand takes place within 10 min at 28 degrees C. Similarly, receptor bound to estriol (E3) at 0 degrees C changes, when heated, from a state with fast into a state with slow E3 dissociation. The main difference between RE2 and RE3 was that E3 dissociates from unheated 8S RE3 and heat-transformed 5S RE3 at a much faster rate than E2 from RE2 . In the mature ovariectomized rat a slow dissociating 5S receptor estrogen complex is found in nuclei 1 h after injection of [3H]E2 or [3H]E3. In vitro dissociation of these 2 estrogens from this nuclear bound receptor formed in vivo takes place at rates similar to those from heat-transformed cytosolic RE2 or RE3 complexes. Addition of pyridoxal 5'-phosphate (PLP) to the slow-dissociating heat-transformed 5S estrogen receptor complexes causes rapid dissociation of E2 or E3; this effect is dose-dependent and is not due to disruption of 5S dimers, since after PLP addition RE2 and RE3 sediment unchanged as 5S dimers. The presence of a large excess of non-radioactive 4S RE3 does not interfere with the temperature induced rapid transition of 4S R[3H]E2 complexes from the state with fast into a state with slow E2 dissociation kinetics. A model is presented to explain the temperature induced biphasic estrogen dissociation from the receptor. It is proposed that the low affinity 4S RE2 monomer undergoes a temperature and estrogen dependent conformation change, such that the ligand is "locked" into the receptor's binding site. This conformational change results in the formation of a high affinity 4S monomer from which estrogen dissociates at a slower rate. This reaction is independent from subsequent 4S to 5S dimerization (transformation). The different rates of ligand dissociation from the low and high affinity 4S receptors reflect the different interactions (hydrophobic and hydrogen bonding) of E2 and E3 with the estrogen binding domain.
与雌二醇（E2）结合的胞质雌激素受体（小牛子宫）在0℃时处于E2解离速率快的状态，当置于28℃时会转变为E2解离速率慢的状态。这种受体对其配体亲和力的温度加速转变在28℃下10分钟内发生。同样，与雌三醇（E3）结合的受体在0℃时加热后，会从E3解离速率快的状态转变为E3解离速率慢的状态。RE2和RE3之间的主要区别在于，E3从未加热的8S RE3和热转化的5S RE3上解离的速率比E2从RE2上解离的速率快得多。在成熟的去卵巢大鼠中，注射[3H]E2或[3H]E3 1小时后，在细胞核中发现了一种解离缓慢的5S受体雌激素复合物。这两种雌激素从体内形成的这种核结合受体上的体外解离速率与从热转化的胞质RE2或RE3复合物上的解离速率相似。向解离缓慢的热转化5S雌激素受体复合物中添加磷酸吡哆醛（PLP）会导致E2或E3迅速解离；这种效应是剂量依赖性的，并非由于5S二聚体的破坏，因为添加PLP后，RE2和RE3作为5S二聚体沉淀不变。大量过量的非放射性4S RE3的存在并不干扰温度诱导的4S R[3H]E2复合物从E2解离动力学快的状态到慢的状态的快速转变。提出了一个模型来解释温度诱导的雌激素从受体上的双相解离。有人提出，低亲和力的4S RE2单体经历温度和雌激素依赖性的构象变化，使得配体“锁定”在受体的结合位点。这种构象变化导致形成高亲和力的4S单体，雌激素从该单体上解离的速率较慢。该反应独立于随后的4S到5S二聚化（转化）。雌激素从低亲和力和高亲和力4S受体上解离的不同速率反映了E2和E3与雌激素结合域的不同相互作用（疏水和氢键）。
