The aqueous pore through the translocon has a diameter of 40-60 angstrom during cotranslational protein translocation at the ER membrane
The aqueous pore through the translocon has a diameter of 40-60 angstrom during cotranslational protein translocation at the ER membrane
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DOI：
10.1016/s0092-8674(00)80235-4
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发表时间：
1997-05-16
期刊：
影响因子：
64.5
通讯作者：
Johnson, AE
中科院分区：
文献类型：
--
作者：
Hamman, BD;Chen, JC;Johnson, AE
真核分泌蛋白通过跨脂质双分子层的水孔在内质网（ER）膜上进行协同转运。荧光探针被纳入新生分泌蛋白使用修改后的Lys-tRNA，和由此产生的新生链被密封关闭从完全组装的易位中间体的胞质溶胶。然后将不同尺寸的荧光猝灭剂引入ER腔中，以确定哪些足够小以进入孔并猝灭核糖体和/或孔内的探针的荧光。这些可及性研究表明，功能性易位子中的水性孔直径为40-60埃，使其成为迄今为止在必须保持渗透性屏障的膜中观察到的最大孔。
Eukaryotic secretory proteins are cotranslationally translocated through the endoplasmic reticulum (ER) membrane via aqueous pores that span the lipid bilayer. Fluorescent probes were incorporated into nascent secretory proteins using modified Lys-tRNAs, and the resulting nascent chains were sealed off from the cytosol in fully assembled translocation intermediates. Fluorescence quenching agents of different sizes were then introduced into the ER lumen in order to determine which were small enough to enter the pore and to quench the fluorescence of probes inside the ribosome and/or the pore. These accessibility studies showed that the aqueous pore in a functioning translocon is 40-60 Angstrom in diameter, making it the largest hole observed to date in a membrane that must maintain a permeability barrier.