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MARCH6 and TRC8 facilitate the quality control of cytosolic and tail-anchored proteins.

Published version
Peer-reviewed

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Authors

Stefanovic-Barrett, Sandra 
Dickson, Anna S 
Burr, Stephen P 
Williamson, James C 
Lobb, Ian T 

Abstract

Misfolded or damaged proteins are typically targeted for destruction by proteasome-mediated degradation, but the mammalian ubiquitin machinery involved is incompletely understood. Here, using forward genetic screens in human cells, we find that the proteasome-mediated degradation of the soluble misfolded reporter, mCherry-CL1, involves two ER-resident E3 ligases, MARCH6 and TRC8. mCherry-CL1 degradation is routed via the ER membrane and dependent on the hydrophobicity of the substrate, with complete stabilisation only observed in double knockout MARCH6/TRC8 cells. To identify a more physiological correlate, we used quantitative mass spectrometry and found that TRC8 and MARCH6 depletion altered the turnover of the tail-anchored protein heme oxygenase-1 (HO-1). These E3 ligases associate with the intramembrane cleaving signal peptide peptidase (SPP) and facilitate the degradation of HO-1 following intramembrane proteolysis. Our results highlight how ER-resident ligases may target the same substrates, but work independently of each other, to optimise the protein quality control of selected soluble and tail-anchored proteins.

Description

Keywords

ERAD, MARCH6, TRC8, intramembrane proteolysis, protein quality control, Endoplasmic Reticulum, Gene Knockout Techniques, HeLa Cells, Heme Oxygenase-1, Humans, Mass Spectrometry, Membrane Proteins, Proteolysis, Receptors, Cell Surface, Ubiquitin-Protein Ligases, Ubiquitination

Journal Title

EMBO Rep

Conference Name

Journal ISSN

1469-221X
1469-3178

Volume Title

19

Publisher

Springer Science and Business Media LLC
Sponsorship
Wellcome Trust (102770/Z/13/Z)
Wellcome Trust (101835/Z/13/Z)
MRC (1625900)
Wellcome Trust (084957/Z/08/Z)
Wellcome Trust (100140/Z/12/Z)
Wellcome Trust (210688/Z/18/Z)