Selective photochemical treatment of oestrogen receptor in a Xenopus liver extract destroys hormone binding and transcriptional activation but not DNA binding.
Selective photochemical treatment of oestrogen receptor in a Xenopus liver extract destroys hormone binding and transcriptional activation but not DNA binding.
复制标题
对爪蟾肝脏提取物中的雌激素受体进行选择性光化学处理会破坏激素结合和转录激活，但不会破坏 DNA 结合。
作者：
N. Cridland;C. Wright;E. A. Mckenzie;J. Knowland
使用UV-A范围内的光对雌二醇的简单衍生物进行光化学激发，完全、永久和选择性地灭活非洲爪蟾肝脏提取物中存在的雌激素受体蛋白，而不影响其整体大小。结合位点的失活以简单的一级动力学完成。过量的雌二醇可以防止失活，但非雌激素类固醇不能。使用体外转录系统，我们表明，治疗消除了卵黄蛋白原基因的转录，这是正常的雌激素反应，但对白蛋白基因的转录没有影响，这不是。天然受体与卵黄蛋白原B2基因中的两个不完全回文序列结合，这两个序列共同构成雌激素反应单位。它对一个序列的亲和力大于对另一个序列的亲和力，这表明当受体与B2基因相互作用时，强制结合顺序起作用。光失活的受体仍然与两个序列结合，但亲和力降低。我们还讨论了我们的研究结果的背景下，目前的关注紫外线对人体组织的影响。
Photochemical excitation of a simple derivative of oestradiol using light in the UV‐A range totally, permanently and selectively inactivates the oestrogen receptor protein present in a Xenopus liver extract without affecting its overall size. Inactivation of the binding site proceeds to completion with simple, first‐order kinetics. Inactivation is prevented by excess oestradiol but not by non‐oestrogenic steroids. Using an in vitro transcription system, we show that the treatment eliminates transcription of vitellogenin genes, which are normally oestrogen‐responsive, but has no effect on the transcription of albumin genes, which are not. Native receptor binds to the two imperfectly palindromic sequences in the vitellogenin B2 gene which together constitute an oestrogen‐response unit. Its affinity for one sequence is greater than its affinity for the other, suggesting that a compulsory binding order operates when receptor interacts with the B2 gene. Photoinactivated receptor still binds to both sequences, but with reduced affinity. We also discuss our findings in the context of the current concern over the effects of UV‐A on human tissues.