The Aqueous Pore through the Translocon Has a Diameter of 40–60 Å during Cotranslational Protein Translocation at the ER Membrane
CellPublished 1 May 1997Open access
Brian D. Hamman, Jui‐Chang Chen, Edward E. Johnson, Arthur E. Johnson
Citations278
SJR quartileQ1
SJR score22.61
SNIP7.62
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TL;DR
Accessibility studies showed that the aqueous pore in a functioning translocon is 40-60 A in diameter, making it the largest hole observed to date in a membrane that must maintain a permeability barrier.
Abstract
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 A in diameter, making it the largest hole observed to date in a membrane that must maintain a permeability barrier.
Keywords
Materials ScienceBiochemistry, Genetics and Molecular Biology
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