A low-affinity estrogen-binding site in pregnant rat uteri: analysis and partial purification.
A low-affinity estrogen-binding site in pregnant rat uteri: analysis and partial purification.
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怀孕大鼠子宫中的低亲和力雌激素结合位点：分析和部分纯化。
DOI：
10.1073/pnas.91.24.11502
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发表时间：
1994
影响因子：
11.1
通讯作者：
S. Biswas
中科院分区：
文献类型：
--
作者：
W. Gray;E. Biswas;N. Bashirelahi;S. Biswas
我们已经确定了一个低亲和力（II型）雌激素结合位点（EBS），在怀孕期间在大鼠子宫内高水平表达。虽然在未怀孕的大鼠子宫中可以检测到这种活性，但其含量（0.094 pmol/g子宫）比高亲和力的I型雌激素受体（0.57 pmol/g子宫）低几倍。妊娠期间，在妊娠19-20天，低亲和力的II型EBS成为大鼠子宫内主要的雌激素结合位点（>或= 88%）。子宫内低亲和型EBS （7.9 pmol/g）水平增加了约85倍，比活性增加了约20倍（0.39 pmol/mg），而高亲和型EBS保持相对不变。我们报告了一种从妊娠大鼠子宫中纯化II型EBS的方法，并对其DNA和类固醇结合特性进行了分析。雌二醇结合研究和Scatchard分析表明，II型EBS具有明显的雌二醇结合亲和力，为>或= 24 nM。凝胶过滤和SDS/PAGE分析表明，II型EBS是一个单体73-kDa蛋白。雌二醇的结合在大量过量的他莫昔芬、萘氧化胺或二氢睾酮的存在下仍明显不受抑制。雌二醇、己烯雌酚和槲皮素（一种II型ebs特异性抑制剂）有效竞争。纯化的低亲和力EBS与雌激素应答元件没有序列特异性的dna结合活性，这表明它与I型雌激素受体的功能不同。
We have identified a low-affinity (type II) estrogen-binding site (EBS) that is expressed at high levels during pregnancy in rat uteri. Although this activity was detectable in nonpregnant rat uteri, it was present in amounts (0.094 pmol/g of uteri) that were severalfold lower than the high-affinity type I estrogen receptor (0.57 pmol/g of uteri). During pregnancy, at 19-20 days of gestation, the low-affinity type II EBS became the major (> or = 88%) estrogen-binding site in rat uteri. The increase in the level of low-affinity EBS (7.9 pmol/g) in uteri was approximately 85-fold with an approximately 20-fold increase in the specific activity (0.39 pmol/mg) of this form, whereas the high-affinity form remained relatively unchanged. We report here a method of purification of type II EBS from pregnant rat uteri and present an analysis of its DNA and steroid-binding properties. Estradiol-binding studies and Scatchard analysis showed that the type II EBS had an apparent estradiol-binding affinity of > or = 24 nM. Gel filtration and SDS/PAGE analysis indicated that the type II EBS was a monomeric 73-kDa protein. The estradiol binding remained apparently uninhibited in the presence of a large excess of tamoxifen, nafoxidine, or dihydrotestosterone. Estradiol, diethylstilbestrol, and quercitin (a type II EBS-specific inhibitor) competed efficiently. The purified low-affinity EBS did not have sequence-specific DNA-binding activity with the estrogen-responsive element, which indicated that it differs in function from the type I estrogen receptor.