scholarly journals The expanding role of the ER translocon in membrane protein folding

2007 ◽  
Vol 179 (7) ◽  
pp. 1333-1335 ◽  
Author(s):  
William R. Skach
Keyword(s):  
Protein Folding ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Functional Organization ◽  
Conducting Channel ◽  
Membrane Protein Folding ◽  
Protein Biogenesis ◽  
Insight Into ◽  
Er Membrane

Eukaryotic polytopic membrane proteins are cotranslationally inserted into the ER membrane by a multisubunit protein-conducting channel called the Sec61 translocon. Although most major translocon components have been identified and reconstituted, their stoichiometry and functional organization remain unknown. This has led to speculative and sometimes conflicting models describing how multiple transmembrane (TM) segments might be oriented and integrated during nascent polytopic protein biogenesis. Kida et al. (see p. 1441 of this issue) shed new insight into this area by demonstrating that functional translocons exhibit a remarkable flexibility by simultaneously accommodating at least two hydrophilic translocating peptides that are separated by multiple hydrophobic TMs. These surprising findings support an expanded role for the translocon in membrane protein biogenesis and require reassessment of current views based on a single small functional pore.

scholarly journals SecY alterations that impair membrane protein folding and generate a membrane stress

2007 ◽  
Vol 176 (3) ◽  
pp. 307-317 ◽  
Author(s):  
Nobuyuki Shimohata ◽  
Shushi Nagamori ◽  
Yoshinori Akiyama ◽  
H. Ronald Kaback ◽  
Koreaki Ito
Keyword(s):  
Protein Folding ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Signal Recognition Particle ◽  
Membrane Vesicles ◽  
In Vitro Translation ◽  
Membrane Protein Folding ◽  
Protein Biogenesis ◽  
Simple Reduction

We report on a class of Escherichia coli SecY mutants that impair membrane protein folding. The mutants also up-regulate the Cpx/σE stress response pathways. Similar stress induction was also observed in response to a YidC defect in membrane protein biogenesis but not in response to the signal recognition particle–targeting defect or in response to a simple reduction in the abundance of the translocon. Together with the previous contention that the Cpx system senses a protein abnormality not only at periplasmic and outer membrane locations but also at the plasma membrane, abnormal states of membrane proteins are postulated to be generated in these secY mutants. In support of this notion, in vitro translation, membrane integration, and folding of LacY reveal that mutant membrane vesicles allow the insertion of LacY but not subsequent folding into a normal conformation recognizable by conformation-specific antibodies. The results demonstrate that normal SecY function is required for the folding of membrane proteins after their insertion into the translocon.

scholarly journals 2P103 Direct monitoring of membrane protein folding process during in-vitro expression by Surface Enhanced IR spectroscopy(03. Membrane proteins,Poster)

2013 ◽  
Vol 53 (supplement1-2) ◽  
pp. S176
Author(s):  
Kenichi Ataka ◽  
Joachim Heberle ◽  
Axel Baumann ◽  
Silke Kerruth ◽  
Ramona Schlesinger ◽  
...  
Keyword(s):  
Protein Folding ◽  
Membrane Proteins ◽  
Ir Spectroscopy ◽  
Membrane Protein ◽  
In Vitro Expression ◽  
Folding Process ◽  
Membrane Protein Folding ◽  
Surface Enhanced

scholarly journals The Role of the Membrane-Water Interface in Co-Translational Membrane Protein Folding

2021 ◽  
Vol 120 (3) ◽  
pp. 134a
Author(s):  
Jan Steinkühler ◽  
Sharon M. Loverde ◽  
Neha P. Kamat
Keyword(s):  
Protein Folding ◽  
Membrane Protein ◽  
Water Interface ◽  
Membrane Protein Folding

TMCC3 localizes at the three-way junctions for the proper tubular network of the endoplasmic reticulum

2019 ◽  
Vol 476 (21) ◽  
pp. 3241-3260
Author(s):  
Sindhu Wisesa ◽  
Yasunori Yamamoto ◽  
Toshiaki Sakisaka
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Mammalian Cells ◽  
Coiled Coil ◽  
Transmembrane Domains ◽  
Domain Family ◽  
Coiled Coil Domain ◽  
U2os Cells ◽  
Er Membrane

The tubular network of the endoplasmic reticulum (ER) is formed by connecting ER tubules through three-way junctions. Two classes of the conserved ER membrane proteins, atlastins and lunapark, have been shown to reside at the three-way junctions so far and be involved in the generation and stabilization of the three-way junctions. In this study, we report TMCC3 (transmembrane and coiled-coil domain family 3), a member of the TEX28 family, as another ER membrane protein that resides at the three-way junctions in mammalian cells. When the TEX28 family members were transfected into U2OS cells, TMCC3 specifically localized at the three-way junctions in the peripheral ER. TMCC3 bound to atlastins through the C-terminal transmembrane domains. A TMCC3 mutant lacking the N-terminal coiled-coil domain abolished localization to the three-way junctions, suggesting that TMCC3 localized independently of binding to atlastins. TMCC3 knockdown caused a decrease in the number of three-way junctions and expansion of ER sheets, leading to a reduction of the tubular ER network in U2OS cells. The TMCC3 knockdown phenotype was partially rescued by the overexpression of atlastin-2, suggesting that TMCC3 knockdown would decrease the activity of atlastins. These results indicate that TMCC3 localizes at the three-way junctions for the proper tubular ER network.

Spatial localization of unknown proteins in the endoplasmic reticulum predicts functions

2007 ◽  
Vol 30 (4) ◽  
pp. 84
Author(s):  
Michael D. Jain ◽  
Hisao Nagaya ◽  
Annalyn Gilchrist ◽  
Miroslaw Cygler ◽  
John J.M. Bergeron
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Folding ◽  
Protein Synthesis ◽  
Protein Function ◽  
Protein Translocation ◽  
Spatial Localization ◽  
Predict Protein Function ◽  
Insight Into ◽  
Soluble Fractions ◽  
Er Membrane

Protein synthesis, folding and degradation functions are spatially segregated in the endoplasmic reticulum (ER) with respect to the membrane and the ribosome (rough and smooth ER). Interrogation of a proteomics resource characterizing rough and smooth ER membranes subfractionated into cytosolic, membrane, and soluble fractions gives a spatial map of known proteins involved in ER function. The spatial localization of 224 identified unknown proteins in the ER is predicted to give insight into their function. Here we provide evidence that the proteomics resource accurately predicts the function of new proteins involved in protein synthesis (nudilin), protein translocation across the ER membrane (nicalin), co-translational protein folding (stexin), and distal protein folding in the lumen of the ER (erlin-1, TMX2). Proteomics provides the spatial localization of proteins and can be used to accurately predict protein function.

scholarly journals Applications of Single-Molecule Methods to Membrane Protein Folding Studies

2018 ◽  
Vol 430 (4) ◽  
pp. 424-437 ◽  
Author(s):  
Robert E. Jefferson ◽  
Duyoung Min ◽  
Karolina Corin ◽  
Jing Yang Wang ◽  
James U. Bowie
Keyword(s):  
Protein Folding ◽  
Membrane Protein ◽  
Single Molecule ◽  
Membrane Protein Folding

scholarly journals In-Situ Observation of Membrane Protein Folding during Cell-Free Expression

PLoS ONE ◽  
2016 ◽  
Vol 11 (3) ◽  
pp. e0151051 ◽  
Author(s):  
Axel Baumann ◽  
Silke Kerruth ◽  
Jörg Fitter ◽  
Georg Büldt ◽  
Joachim Heberle ◽  
...  
Keyword(s):  
Protein Folding ◽  
Membrane Protein ◽  
Free Expression ◽  
In Situ Observation ◽  
Membrane Protein Folding
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