Hayward M A, Mitchell T A, Shapiro D J
J Biol Chem. 1980 Dec 10;255(23):11308-12.
The levels of cytoplasmic and nuclear estrogen receptor have been determined in livers of male Xenopus laevis stimulated by estradiol-17 beta to synthesize vitellogenin mRNA. Estrogen receptor levels were also determined in unstimulated liver and following long term withdrawal of estrogen. In unstimulated liver cells, which do not contain detectable vitellogenin mRNA, more than 80% of the estrogen receptor is located in the nucleus (550 high affinity estrogen binding sites/nucleus), while the cytoplasm contains only 100 high affinity estrogen binding sites/cell. Administration of estradiol-17 beta, which induces massive synthesis and accumulation of vitellogenin mRNA, induces the estrogen receptor as well. The nuclear receptor level rises to approximately 2,000 estrogen binding sites/cell, while the cytosol receptor increases to only 150 sites/cel. Liver cells of male X. laevis which have been withdrawn from estrogen for 70 days exhibit a striking change in receptor levels. The nuclear receptor returns to the level prevailing in unstimulated cells (approximately 500 sites/cell) while the cytosol receptor level rises to more than 1,200 sites/cell (equivalent to 260 fmol/g of tissue). The existence of a pool of cytosol receptor, which is rapidly available for induction of vitellogenin mRNA, may in part explain the shorter lag period and more rapid induction of vitellogenin mRNA observed during secondary estrogen stimulation of withdrawn Xenopus liver cells.
已测定了经17β-雌二醇刺激以合成卵黄蛋白原mRNA的雄性非洲爪蟾肝脏中细胞质和细胞核雌激素受体的水平。还测定了未受刺激肝脏以及长期撤除雌激素后的雌激素受体水平。在未受刺激的肝细胞中，其不含有可检测到的卵黄蛋白原mRNA，超过80%的雌激素受体位于细胞核中（每个细胞核有550个高亲和力雌激素结合位点），而细胞质中每个细胞仅含有100个高亲和力雌激素结合位点。给予诱导卵黄蛋白原mRNA大量合成和积累的17β-雌二醇，也会诱导雌激素受体。细胞核受体水平升至约每个细胞2000个雌激素结合位点，而胞质溶胶受体仅增加至每个细胞150个位点。已撤除雌激素70天的雄性非洲爪蟾肝细胞的受体水平出现显著变化。细胞核受体恢复到未受刺激细胞中的水平（约每个细胞500个位点），而胞质溶胶受体水平升至超过每个细胞1200个位点（相当于260飞摩尔/克组织）。存在一个可快速用于诱导卵黄蛋白原mRNA的胞质溶胶受体池，这可能部分解释了在对撤除雌激素的爪蟾肝细胞进行二次雌激素刺激期间观察到的卵黄蛋白原mRNA较短的延迟期和更快的诱导现象。
