scholarly journals Sedimentation Equilibrium of a Small Oligomer-forming Membrane Protein: Effect of Histidine Protonation on Pentameric Stability

10.3791/52404 ◽  
2015 ◽  
Author(s):  
Wahyu Surya ◽  
Jaume Torres
Keyword(s):  
Membrane Protein ◽  
Sedimentation Equilibrium ◽  
Small Oligomer

scholarly journals A novel lipid-polymer system with unique properties has potential in drug delivery and biotechnology applications

2018 ◽  
Author(s):  
Monica D. Rieth ◽  
Kerney Jebrell Glover
Keyword(s):  
Drug Delivery ◽  
Membrane Protein ◽  
Protein Interactions ◽  
Polymer System ◽  
Short Chain ◽  
Sedimentation Equilibrium ◽  
Structural Studies ◽  
Phosphorus Nmr ◽  
Detergent Micelle ◽  
Long Chain

AbstractThe utility of detergent micelle and bicelle systems has been demonstrated to be a valuable tool for the study of membrane protein interactions and in structural studies. Bicelles are distinguished from micelles in that they contain a lipid bilayer that mimics the plasma membrane of cells making it more native-like than its detergent micelle counter-part. Bicelles are typically comprised of a long-chain phospholipid such as 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and either a short-chain phospholipid, typically 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), or a bile-salt derivative such as CHAPS or CHAPSO. In solution DMPC and DHPC bicelles assume a discoidal structure comprised of a heterogeneous arrangement where the short-chain lipids gather around the rim of the disk and the long-chain lipids form the flat, bilayer region of the bicelle. Aside from DHPC, CHAPS and CHAPSO few other detergents have reportedly been investigated for their ability to form bicelles with DMPC. In this study, the detergent, C8E5, was used to prepare mixtures with DMPC to determine if it adopts properties similar to DMPC-DHPC bicelles. Mixtures were evaluated using sedimentation equilibrium, 31P-phosphorus NMR, and light scattering and compared to DMPC-DHPC bicelles. Interestingly, mixtures of DMPC and C8E5 assumed a spherical-shaped micellar structure, not the predicted discoidal shape. DMPC-C8E5 mixtures retain interesting properties rendering them particularly advantageous in studies of membrane protein interactions and hold promise as vehicles for drug delivery.

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.

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