scholarly journals Golgi membrane protein Erd1 Is essential for recycling a subset of Golgi glycosyltransferases

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Richa Sardana ◽  
Carolyn M Highland ◽  
Beth E Straight ◽  
Christopher F Chavez ◽  
J Christopher Fromme ◽  
...  
Keyword(s):  
Steady State ◽  
Membrane Protein ◽  
Integral Membrane Protein ◽  
Protein Glycosylation ◽  
Sequential Process ◽  
Golgi Membrane ◽  
Present Evidence ◽  
Cytosolic Receptor

Protein glycosylation in the Golgi is a sequential process that requires proper distribution of transmembrane glycosyltransferase enzymes in the appropriate Golgi compartments. Some of the cytosolic machinery required for the steady-state localization of some Golgi enzymes are known but existing models do not explain how many of these enzymes are localized. Here, we uncover the role of an integral membrane protein in yeast, Erd1, as a key facilitator of Golgi glycosyltransferase recycling by directly interacting with both the Golgi enzymes and the cytosolic receptor, Vps74. Loss of Erd1 function results in mislocalization of Golgi enzymes to the vacuole/lysosome. We present evidence that Erd1 forms an integral part of the recycling machinery and ensures productive recycling of several early Golgi enzymes. Our work provides new insights on how the localization of Golgi glycosyltransferases is spatially and temporally regulated, and is finely tuned to the cues of Golgi maturation.

scholarly journals A Novel Golgi Membrane Protein Is a Partner of the ARF Exchange Factors Gea1p and Gea2p

2003 ◽  
Vol 14 (6) ◽  
pp. 2357-2371 ◽  
Author(s):  
Sophie Chantalat ◽  
Rëgis Courbeyrette ◽  
Francesca Senic-Matuglia ◽  
Catherine L. Jackson ◽  
Bruno Goud ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Trafficking ◽  
Transmembrane Domain ◽  
Integral Membrane Protein ◽  
Membrane Dynamics ◽  
General Interest ◽  
Single Mutation ◽  
Golgi Membrane ◽  
Nucleotide Exchange

The Sec7 domain guanine nucleotide exchange factors (GEFs) for the GTPase ARF are highly conserved regulators of membrane dynamics and protein trafficking. The interactions of large ARF GEFs with cellular membranes for localization and/or activation are likely to participate in regulated recruitment of ARF and effectors. However, these interactions remain largely unknown. Here we characterize Gmh1p, the first Golgi transmembrane-domain partner of any of the high-molecular-weight ARF-GEFs. Gmh1p is an evolutionarily conserved protein. We demonstrate molecular interaction between the yeast Gmh1p and the large ARF-GEFs Gea1p and Gea2p. This interaction involves a domain of Gea1p and Gea2p that is conserved in the eukaryotic orthologues of the Gea proteins. A single mutation in a conserved amino acid residue of this domain is sufficient to abrogate the interaction, whereas the overexpression of Gmh1p can compensate in vivo defects caused by mutations in this domain. We show that Gmh1p is an integral membrane protein that localizes to the early Golgi in yeast and in human HeLa cells and cycles through the ER. Hence, we propose that Gmh1p acts as a positive Golgi-membrane partner for Gea function. These results are of general interest given the evolutionary conservation of both ARF-GEFs and the Gmh proteins.

scholarly journals Quantitative Proteomics Links the LRRC59 Interactome to mRNA Translation on the ER Membrane

2020 ◽  
Vol 19 (11) ◽  
pp. 1826-1849
Author(s):  
Molly M. Hannigan ◽  
Alyson M. Hoffman ◽  
J. Will Thompson ◽  
Tianli Zheng ◽  
Christopher V. Nicchitta
Keyword(s):  
Protein Synthesis ◽  
Steady State ◽  
Membrane Protein ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Mrna Translation ◽  
Integral Membrane Protein ◽  
Translation Factors ◽  
Er Membrane

Protein synthesis on the endoplasmic reticulum (ER) requires the dynamic coordination of numerous cellular components. Together, resident ER membrane proteins, cytoplasmic translation factors, and both integral membrane and cytosolic RNA-binding proteins operate in concert with membrane-associated ribosomes to facilitate ER-localized translation. Little is known, however, regarding the spatial organization of ER-localized translation. This question is of growing significance as it is now known that ER-bound ribosomes contribute to secretory, integral membrane, and cytosolic protein synthesis alike. To explore this question, we utilized quantitative proximity proteomics to identify neighboring protein networks for the candidate ribosome interactors SEC61β (subunit of the protein translocase), RPN1 (oligosaccharyltransferase subunit), SEC62 (translocation integral membrane protein), and LRRC59 (ribosome binding integral membrane protein). Biotin labeling time course studies of the four BioID reporters revealed distinct labeling patterns that intensified but only modestly diversified as a function of labeling time, suggesting that the ER membrane is organized into discrete protein interaction domains. Whereas SEC61β and RPN1 reporters identified translocon-associated networks, SEC62 and LRRC59 reporters revealed divergent protein interactomes. Notably, the SEC62 interactome is enriched in redox-linked proteins and ER luminal chaperones, with the latter likely representing proximity to an ER luminal chaperone reflux pathway. In contrast, the LRRC59 interactome is highly enriched in SRP pathway components, translation factors, and ER-localized RNA-binding proteins, uncovering a functional link between LRRC59 and mRNA translation regulation. Importantly, analysis of the LRRC59 interactome by native immunoprecipitation identified similar protein and functional enrichments. Moreover, [35S]-methionine incorporation assays revealed that siRNA silencing of LRRC59 expression reduced steady state translation levels on the ER by ca. 50%, and also impacted steady state translation levels in the cytosol compartment. Collectively, these data reveal a functional domain organization for the ER and identify a key role for LRRC59 in the organization and regulation of local translation.

scholarly journals Functional assessment of SLC4A11, an integral membrane protein mutated in corneal dystrophies

2016 ◽  
Vol 311 (5) ◽  
pp. C735-C748 ◽  
Author(s):  
Sampath K. Loganathan ◽  
Hans-Peter Schneider ◽  
Patricio E. Morgan ◽  
Joachim W. Deitmer ◽  
Joseph R. Casey
Keyword(s):  
Membrane Protein ◽  
Mammalian Cells ◽  
Expression System ◽  
Integral Membrane Protein ◽  
Normal Function ◽  
Hek293 Cells ◽  
Cell Swelling ◽  
Xenopus Laevis Oocytes ◽  
Corneal Dystrophies

SLC4A11, a member of the SLC4 family of bicarbonate transporters, is a widely expressed integral membrane protein, abundant in kidney and cornea. Mutations of SLC4A11 cause some cases of the blinding corneal dystrophies, congenital hereditary endothelial dystrophy, and Fuchs endothelial corneal dystrophy. These diseases are marked by fluid accumulation in the corneal stroma, secondary to defective fluid reabsorption by the corneal endothelium. The role of SLC4A11 in these corneal dystrophies is not firmly established, as SLC4A11 function remains unclear. To clarify the normal function(s) of SLC4A11, we characterized the protein following expression in the simple, low-background expression system Xenopus laevis oocytes. Since plant and fungal SLC4A11 orthologs transport borate, we measured cell swelling associated with accumulation of solute borate. The plant water/borate transporter NIP5;1 manifested borate transport, whereas human SLC4A11 did not. SLC4A11 supported osmotically driven water accumulation that was electroneutral and Na+ independent. Studies in oocytes and HEK293 cells could not detect Na+-coupled HCO3− transport or Cl−/HCO3− exchange by SLC4A11. SLC4A11 mediated electroneutral NH3 transport in oocytes. Voltage-dependent OH− or H+ movement was not measurable in SLC4A11-expressing oocytes, but SLC4A11-expressing HEK293 cells manifested low-level cytosolic acidification at baseline. In mammalian cells, but not oocytes, OH−/H+ conductance may arise when SLC4A11 activates another protein or itself is activated by another protein. These data argue against a role of human SLC4A11 in bicarbonate or borate transport. This work provides additional support for water and ammonia transport by SLC4A11. When expressed in oocytes, SLC4A11 transported NH3, not NH3/H+.

The Role of Tryptophan Residues in an Integral Membrane Protein:  Diacylglycerol Kinase†

Biochemistry ◽  
2003 ◽  
Vol 42 (37) ◽  
pp. 11065-11073 ◽  
Author(s):  
Elizabeth H. Clark ◽  
J. Malcolm East ◽  
Anthony G. Lee
Keyword(s):  
Membrane Protein ◽  
Diacylglycerol Kinase ◽  
Integral Membrane Protein ◽  
Tryptophan Residues

Total Chemical Synthesis of the Integral Membrane Protein Influenza A Virus M2:  Role of Its C-Terminal Domain in Tetramer Assembly†

Biochemistry ◽  
1999 ◽  
Vol 38 (37) ◽  
pp. 11905-11913 ◽  
Author(s):  
Gerd G. Kochendoerfer ◽  
David Salom ◽  
James D. Lear ◽  
Rosemarie Wilk-Orescan ◽  
Stephen B. H. Kent ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Chemical Synthesis ◽  
Influenza A Virus ◽  
Influenza A ◽  
Integral Membrane Protein ◽  
Terminal Domain

scholarly journals The role of protein purification in the structure determination of an integral membrane protein

1996 ◽  
Vol 52 (a1) ◽  
pp. C141-C141
Author(s):  
G. McDermott ◽  
S. M. Prince ◽  
M. Z. Papiz ◽  
A. M. Hawthornthwaite-Lawless ◽  
A. A. Freer ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Purification ◽  
Structure Determination ◽  
Integral Membrane Protein

Improving the questions we ask, with Psychology and Cognitive Conflict.

2018 ◽  
Author(s):  
Brett Buttliere
Keyword(s):  
Problem Solving ◽  
Scientific Method ◽  
Meaning Making ◽  
Cognitive Conflict ◽  
Empirical Literature ◽  
Present Evidence ◽  
Scientific Papers ◽  
Science In Society

Over the last decade, there have been many suggestions to improve how scientists answer their questions, but far fewer attempt to improve the questions scientists are asking in the first place. The goal of the paper is then to examine and summarize synthesize the evidence on how to ask the best questions possible. First is a brief review of the philosophical and empirical literature on how the best science is done, which implicitly but not explicitly mentions the role of psychology and especially cognitive conflict. Then we more closely focus on the psychology of the scientist, finding that they are humans, engaged in a meaning making process, and that cognitive conflict is a necessary input for any learning or change in the system. The scientific method is, of course, a specialized meaning making process. We present evidence for this central role of cognitive conflict in science by examining the most discussed scientific papers between 2013 and 2017, which are, in general, controversial and about big problems (e.g., whether vaccines cause autism, how often doctors kill us with their mistakes). Toward the end we discuss the role of science in society, suggesting science itself is an uncertainty reducing and problem solving enterprise. From this basis we encourage scientists to take riskier stances on bigger topics, for the good of themselves and society generally.

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