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A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER

Tail-anchored (TA) proteins play essential roles in mammalian cells, and their accurate localization is critical for proteostasis. Biophysical similarities lead to mistargeting of mitochondrial TA proteins to the ER, where they are delivered to the insertase, the ER membrane protein complex (EMC). L...

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Autores principales: Pleiner, Tino, Hazu, Masami, Pinton Tomaleri, Giovani, Nguyen, Vy N., Januszyk, Kurt, Voorhees, Rebecca M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Rockefeller University Press 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10200711/
https://www.ncbi.nlm.nih.gov/pubmed/37199759
http://dx.doi.org/10.1083/jcb.202212007
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author Pleiner, Tino
Hazu, Masami
Pinton Tomaleri, Giovani
Nguyen, Vy N.
Januszyk, Kurt
Voorhees, Rebecca M.
author_facet Pleiner, Tino
Hazu, Masami
Pinton Tomaleri, Giovani
Nguyen, Vy N.
Januszyk, Kurt
Voorhees, Rebecca M.
author_sort Pleiner, Tino
collection PubMed
description Tail-anchored (TA) proteins play essential roles in mammalian cells, and their accurate localization is critical for proteostasis. Biophysical similarities lead to mistargeting of mitochondrial TA proteins to the ER, where they are delivered to the insertase, the ER membrane protein complex (EMC). Leveraging an improved structural model of the human EMC, we used mutagenesis and site-specific crosslinking to map the path of a TA protein from its cytosolic capture by methionine-rich loops to its membrane insertion through a hydrophilic vestibule. Positively charged residues at the entrance to the vestibule function as a selectivity filter that uses charge-repulsion to reject mitochondrial TA proteins. Similarly, this selectivity filter retains the positively charged soluble domains of multipass substrates in the cytosol, thereby ensuring they adopt the correct topology and enforcing the “positive-inside” rule. Substrate discrimination by the EMC provides a biochemical explanation for one role of charge in TA protein sorting and protects compartment integrity by limiting protein misinsertion.
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spelling pubmed-102007112023-11-18 A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER Pleiner, Tino Hazu, Masami Pinton Tomaleri, Giovani Nguyen, Vy N. Januszyk, Kurt Voorhees, Rebecca M. J Cell Biol Article Tail-anchored (TA) proteins play essential roles in mammalian cells, and their accurate localization is critical for proteostasis. Biophysical similarities lead to mistargeting of mitochondrial TA proteins to the ER, where they are delivered to the insertase, the ER membrane protein complex (EMC). Leveraging an improved structural model of the human EMC, we used mutagenesis and site-specific crosslinking to map the path of a TA protein from its cytosolic capture by methionine-rich loops to its membrane insertion through a hydrophilic vestibule. Positively charged residues at the entrance to the vestibule function as a selectivity filter that uses charge-repulsion to reject mitochondrial TA proteins. Similarly, this selectivity filter retains the positively charged soluble domains of multipass substrates in the cytosol, thereby ensuring they adopt the correct topology and enforcing the “positive-inside” rule. Substrate discrimination by the EMC provides a biochemical explanation for one role of charge in TA protein sorting and protects compartment integrity by limiting protein misinsertion. Rockefeller University Press 2023-05-18 /pmc/articles/PMC10200711/ /pubmed/37199759 http://dx.doi.org/10.1083/jcb.202212007 Text en © 2023 Pleiner et al. https://creativecommons.org/licenses/by-nc-sa/4.0/http://www.rupress.org/terms/This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Pleiner, Tino
Hazu, Masami
Pinton Tomaleri, Giovani
Nguyen, Vy N.
Januszyk, Kurt
Voorhees, Rebecca M.
A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER
title A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER
title_full A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER
title_fullStr A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER
title_full_unstemmed A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER
title_short A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER
title_sort selectivity filter in the er membrane protein complex limits protein misinsertion at the er
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10200711/
https://www.ncbi.nlm.nih.gov/pubmed/37199759
http://dx.doi.org/10.1083/jcb.202212007
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