scholarly journals Cholesterol controls the clustering of the glycophospholipid-anchored membrane receptor for 5-methyltetrahydrofolate.

1990 ◽  
Vol 111 (6) ◽  
pp. 2931-2938 ◽  
Author(s):  
K G Rothberg ◽  
Y S Ying ◽  
B A Kamen ◽  
R G Anderson
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Folate Receptor ◽  
Critical Role ◽  
Membrane Domain ◽  
Glycosyl Phosphatidylinositol ◽  
Membrane Specialization ◽  
Pit Membrane ◽  
Methodological Approaches ◽  
Receptor Clusters

The folate receptor is a glycosyl-phosphatidylinositol (GPI)-anchored membrane protein that mediates the delivery of 5-methyltetrahydrofolate to the cytoplasm of MA104 cells. Ordinarily the receptor is sequestered into numerous discrete clusters that are associated with an uncoated pit membrane specialization called a caveola. By using two different methodological approaches, we found that the maintenance of both receptor clusters and caveolae depends upon the presence of cholesterol in the membrane. These results suggest that cholesterol plays a critical role in maintaining the caveola membrane domain and modulates the interaction of GPI-anchored membrane proteins via their phospholipid anchors.

scholarly journals Design of PG-Surfactants Bearing Polyacrylamide Polymer Chain to Solubilize Membrane Proteins in a Surfactant-Free Buffer

2021 ◽  
Vol 22 (4) ◽  
pp. 1524
Author(s):  
Taro Shimamoto ◽  
Tatsuki Nakakubo ◽  
Tomoyasu Noji ◽  
Shuhei Koeda ◽  
Keisuke Kawakami ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Photophysical Properties ◽  
Gel Filtration ◽  
Bound State ◽  
Research Area ◽  
Membrane Domain ◽  
Protein Surfaces ◽  
Linear Polyacrylamide ◽  
Structure And Functions

The development of techniques capable of using membrane proteins in a surfactant-free aqueous buffer is an attractive research area, and it should be elucidated for various membrane protein studies. To this end, we examined a method using new solubilization surfactants that do not detach from membrane protein surfaces once bound. The designed solubilization surfactants, DKDKC12K-PAn (n = 5, 7, and 18), consist of two parts: one is the lipopeptide-based solubilization surfactant part, DKDKC12K, fand the other is the covalently connected linear polyacrylamide (PA) chain with different Mw values of 5, 7, or 18 kDa. Intermolecular interactions between the PA chains in DKDKC12K-PAn concentrated on the surfaces of membrane proteins via amphiphilic binding of the DKDKC12K part to the integral membrane domain was observed. Therefore, DKDKC12K-PAn (n = 5, 7, and 18) could maintain a bound state even after removal of the unbound by ultrafiltration or gel-filtration chromatography. We used photosystem I (PSI) from Thermosynecoccus vulcanus as a representative to assess the impacts of new surfactants on the solubilized membrane protein structure and functions. Based on the maintenance of unique photophysical properties of PSI, we evaluated the ability of DKDKC12K-PAn (n = 5, 7, and 18) as a new solubilization surfactant.

scholarly journals The influence of the extracellular domains on the dynamic behavior of membrane proteins

2021 ◽  
Author(s):  
Linda Wedemann ◽  
Cenk Onur Gurdap ◽  
Taras Sych ◽  
Erdinc Sezgin
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Dynamics ◽  
Dynamic Behavior ◽  
Transmembrane Domain ◽  
Critical Role ◽  
Cortical Actin ◽  
Extracellular Domains ◽  
The Impact

The dynamic behavior of the plasma membrane proteins mediates various cellular processes, such as cell-cell interactions, transmembrane transport and signaling. It is widely accepted that the dynamics of the membrane proteins is determined either by the interactions of the transmembrane domain with the surrounding lipids or by the interaction of the intracellular domain with cytosolic components such as cortical actin. However, the impact of the extracellular domains (ECDs) on the dynamics of membrane proteins is rather unexplored. Here, we investigate how the ECD size influences protein dynamics in lipid bilayer. We reconstitute ECDs of different molecular weights and heights in model membrane systems and analyze ECD-driven protein sorting in lipid domains as well as protein mobility. We observe that increasing the ECD size leads to a decrease in ordered domain partitioning as well as diffusivity. Our data suggests a critical role of the ECDs on membrane protein behavior in the plasma membrane and paves the way to a more complete understanding of membrane protein dynamics that includes interaction with the extracellular matrix and glycocalyx in health and disease.

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.

Simulation studies of the interactions between membrane proteins and detergents

2005 ◽  
Vol 33 (5) ◽  
pp. 910-912 ◽  
Author(s):  
P.J. Bond ◽  
J. Cuthbertson ◽  
M.S.P. Sansom
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Self Assembly ◽  
Kinetic Mechanism ◽  
Coarse Grained ◽  
Simulation Studies ◽  
High Resolution Data ◽  
Biologically Relevant ◽  
Structure And Dynamics ◽  
Detergent Interactions

Interactions between membrane proteins and detergents are important in biophysical and structural studies and are also biologically relevant in the context of folding and transport. Despite a paucity of high-resolution data on protein–detergent interactions, novel methods and increased computational power enable simulations to provide a means of understanding such interactions in detail. Simulations have been used to compare the effect of lipid or detergent on the structure and dynamics of membrane proteins. Moreover, some of the longest and most complex simulations to date have been used to observe the spontaneous formation of membrane protein–detergent micelles. Common mechanistic steps in the micelle self-assembly process were identified for both α-helical and β-barrel membrane proteins, and a simple kinetic mechanism was proposed. Recently, simplified (i.e. coarse-grained) models have been utilized to follow long timescale transitions in membrane protein–detergent assemblies.

scholarly journals Membrane recruitment of Atg8 by Hfl1 facilitates turnover of vacuolar membrane proteins in yeast cells approaching stationary phase

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Cheng-Wen He ◽  
Xue-Fei Cui ◽  
Shao-Jie Ma ◽  
Qin Xu ◽  
Yan-Peng Ran ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Stationary Phase ◽  
Molecular Mechanisms ◽  
Multivesicular Body ◽  
Degradation Process ◽  
Vacuolar Membrane ◽  
Yeast Cells ◽  
Membrane Structures ◽  
Membrane Recruitment

Abstract Background The vacuole/lysosome is the final destination of autophagic pathways, but can also itself be degraded in whole or in part by selective macroautophagic or microautophagic processes. Diverse molecular mechanisms are involved in these processes, the characterization of which has lagged behind those of ATG-dependent macroautophagy and ESCRT-dependent endosomal multivesicular body pathways. Results Here we show that as yeast cells gradually exhaust available nutrients and approach stationary phase, multiple vacuolar integral membrane proteins with unrelated functions are degraded in the vacuolar lumen. This degradation depends on the ESCRT machinery, but does not strictly require ubiquitination of cargos or trafficking of cargos out of the vacuole. It is also temporally and mechanistically distinct from NPC-dependent microlipophagy. The turnover is facilitated by Atg8, an exception among autophagy proteins, and an Atg8-interacting vacuolar membrane protein, Hfl1. Lack of Atg8 or Hfl1 led to the accumulation of enlarged lumenal membrane structures in the vacuole. We further show that a key function of Hfl1 is the membrane recruitment of Atg8. In the presence of Hfl1, lipidation of Atg8 is not required for efficient cargo turnover. The need for Hfl1 can be partially bypassed by blocking Atg8 delipidation. Conclusions Our data reveal a vacuolar membrane protein degradation process with a unique dependence on vacuole-associated Atg8 downstream of ESCRTs, and we identify a specific role of Hfl1, a protein conserved from yeast to plants and animals, in membrane targeting of Atg8.

scholarly journals Membrane Protein Stabilization Strategies for Structural and Functional Studies

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 155
Author(s):  
Ekaitz Errasti-Murugarren ◽  
Paola Bartoccioni ◽  
Manuel Palacín
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Lipid Membrane ◽  
Protein Stabilization ◽  
New Drugs ◽  
Cell Physiology ◽  
Protein Preparation ◽  
Functional Studies ◽  
Membrane Protein Stability ◽  
Druggable Targets

Accounting for nearly two-thirds of known druggable targets, membrane proteins are highly relevant for cell physiology and pharmacology. In this regard, the structural determination of pharmacologically relevant targets would facilitate the intelligent design of new drugs. The structural biology of membrane proteins is a field experiencing significant growth as a result of the development of new strategies for structure determination. However, membrane protein preparation for structural studies continues to be a limiting step in many cases due to the inherent instability of these molecules in non-native membrane environments. This review describes the approaches that have been developed to improve membrane protein stability. Membrane protein mutagenesis, detergent selection, lipid membrane mimics, antibodies, and ligands are described in this review as approaches to facilitate the production of purified and stable membrane proteins of interest for structural and functional studies.

scholarly journals Craniofacial Diseases Caused by Defects in Intracellular Trafficking

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 726
Author(s):  
Chung-Ling Lu ◽  
Jinoh Kim
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Intracellular Trafficking ◽  
Critical Role ◽  
Treatment Strategies ◽  
Soluble Proteins ◽  
Genes Encoding ◽  
Membrane Bound ◽  
Signaling Receptors ◽  
Craniofacial Morphogenesis

Cells use membrane-bound carriers to transport cargo molecules like membrane proteins and soluble proteins, to their destinations. Many signaling receptors and ligands are synthesized in the endoplasmic reticulum and are transported to their destinations through intracellular trafficking pathways. Some of the signaling molecules play a critical role in craniofacial morphogenesis. Not surprisingly, variants in the genes encoding intracellular trafficking machinery can cause craniofacial diseases. Despite the fundamental importance of the trafficking pathways in craniofacial morphogenesis, relatively less emphasis is placed on this topic, thus far. Here, we describe craniofacial diseases caused by lesions in the intracellular trafficking machinery and possible treatment strategies for such diseases.

scholarly journals A microfluidic strategy for the detection of membrane protein interactions

Lab on a Chip ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 3230-3238
Author(s):  
Yuewen Zhang ◽  
Therese W. Herling ◽  
Stefan Kreida ◽  
Quentin A. E. Peter ◽  
Tadas Kartanas ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Interactions ◽  
Native Solution ◽  
Exchange Of Information ◽  
Extracellular Environment

Membrane proteins are gatekeepers for exchange of information and matter between the intracellular and extracellular environment. This paper opens up a route to probe membrane protein interactions under native solution conditions using microfluidics.

Three-dimensional crystallization of membrane proteins

1988 ◽  
Vol 21 (4) ◽  
pp. 429-477 ◽  
Author(s):  
W. Kühlbrandt
Keyword(s):  
High Resolution ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Three Dimensional ◽  
Biological Macromolecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Membrane Protein Complexes ◽  
Essential Prerequisite

As recently as 10 years ago, the prospect of solving the structure of any membrane protein by X-ray crystallography seemed remote. Since then, the threedimensional (3-D) structures of two membrane protein complexes, the bacterial photosynthetic reaction centres of Rhodopseudomonas viridis (Deisenhofer et al. 1984, 1985) and of Rhodobacter sphaeroides (Allen et al. 1986, 1987 a, 6; Chang et al. 1986) have been determined at high resolution. This astonishing progress would not have been possible without the pioneering work of Michel and Garavito who first succeeded in growing 3-D crystals of the membrane proteins bacteriorhodopsin (Michel & Oesterhelt, 1980) and matrix porin (Garavito & Rosenbusch, 1980). X-ray crystallography is still the only routine method for determining the 3-D structures of biological macromolecules at high resolution and well-ordered 3-D crystals of sufficient size are the essential prerequisite.

scholarly journals NCU-G1 is a highly glycosylated integral membrane protein of the lysosome

2009 ◽  
Vol 422 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Oliver Schieweck ◽  
Markus Damme ◽  
Bernd Schröder ◽  
Andrej Hasilik ◽  
Bernhard Schmidt ◽  
...  
Keyword(s):  
Amino Acid ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Mouse Liver ◽  
Lysosomal Membrane ◽  
Molecular Forms ◽  
Type I ◽  
Calculated Molecular Mass ◽  
Sorting Motif ◽  
Lysosomal Membrane Proteins

Until recently, a modest number of approx. 40 lysosomal membrane proteins had been identified and even fewer were characterized in their function. In a proteomic study, using lysosomal membranes from human placenta we identified several candidate lysosomal membrane proteins and proved the lysosomal localization of two of them. In the present study, we demonstrate the lysosomal localization of the mouse orthologue of the human C1orf85 protein, which has been termed kidney-predominant protein NCU-G1 (GenBank® accession number: AB027141). NCU-G1 encodes a 404 amino acid protein with a calculated molecular mass of 39 kDa. The bioinformatics analysis of its amino acid sequence suggests it is a type I transmembrane protein containing a single tyrosine-based consensus lysosomal sorting motif at position 400 within the 12-residue C-terminal tail. Its lysosomal localization was confirmed using immunofluorescence with a C-terminally His-tagged NCU-G1 and the lysosomal marker LAMP-1 (lysosome-associated membrane protein-1) as a reference, and by subcellular fractionation of mouse liver after a tyloxapol-induced density shift of the lysosomal fraction using an anti-NCU-G1 antiserum. In transiently transfected HT1080 and HeLa cells, the His-tagged NCU-G1 was detected in two molecular forms with apparent protein sizes of 70 and 80 kDa, and in mouse liver the endogenous wild-type NCU-G1 was detected as a 75 kDa protein. The remarkable difference between the apparent and the calculated molecular masses of NCU-G1 was shown, by digesting the protein with N-glycosidase F, to be due to an extensive glycosylation. The lysosomal localization was impaired by mutational replacement of an alanine residue for the tyrosine residue within the putative sorting motif.

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