Local−Global Conformational Coupling in a Heptahelical Membrane Protein:  Transport Mechanism from Crystal Structures of the Nine States in the Bacteriorhodopsin Photocycle

Biochemistry ◽  
2004 ◽  
Vol 43 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Janos K. Lanyi ◽  
Brigitte Schobert
Keyword(s):  
Membrane Protein ◽  
Crystal Structures ◽  
Transport Mechanism ◽  
Protein Transport ◽  
Conformational Coupling ◽  
Bacteriorhodopsin Photocycle

Characterization of a novel 63 kDa membrane protein. Implications for the organization of the ER-to-Golgi pathway

1993 ◽  
Vol 104 (3) ◽  
pp. 671-683 ◽  
Author(s):  
A. Schweizer ◽  
M. Ericsson ◽  
T. Bachi ◽  
G. Griffiths ◽  
H.P. Hauri
Keyword(s):  
Membrane Protein ◽  
Laser Scanning ◽  
Protein Transport ◽  
Brefeldin A ◽  
Vero Cells ◽  
Subcellular Fractionation ◽  
Confocal Laser ◽  
Similar Degree ◽  
Fractionation Procedure ◽  
Intermediate Compartment

Owing to the lack of appropriate markers the structural organization of the ER-to-Golgi pathway and the dynamics of its membrane elements have been elusive. To elucidate this organization we have taken a monoclonal antibody (mAb) approach. A mAb against a novel 63 kDa membrane protein (p63) was produced that identifies a large tubular network of smooth membranes in the cytoplasm of primate cells. The distribution of p63 overlaps with the ER-Golgi intermediate compartment, defined by a previously described 53 kDa marker protein (here termed ERGIC-53), as visualized by confocal laser scanning immunofluorescence microscopy and immunoelectron microscopy. The p63 compartment mediates protein transport from the ER to Golgi apparatus, as indicated by partial colocalization of p63 and vesicular stomatitis virus G protein in Vero cells cultured at 15 degrees C. Low temperatures and brefeldin A had little effect on the cellular distribution of p63, suggesting that this novel marker is a stably anchored resident protein of these pre-Golgi membranes. p63 and ERGIC-53 were enriched to a similar degree by the same subcellular fractionation procedure. These findings demonstrate an unanticipated complexity of the ER-Golgi interface and suggest that the ER-Golgi intermediate compartment defined by ERGIC-53 may be part of a greater network of smooth membranes.

scholarly journals Deletion ofPlasmodium falciparumProtein RON3 Affects the Functional Translocation of Exported Proteins and Glucose Uptake

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Leanne M. Low ◽  
Yvonne Azasi ◽  
Emma S. Sherling ◽  
Matthias Garten ◽  
Joshua Zimmerberg ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Glucose Uptake ◽  
Protein Transport ◽  
Dense Granule ◽  
Vacuolar Membrane ◽  
Malarial Parasite ◽  
Membrane Protein Complex ◽  
Erythrocyte Surface ◽  
Dependent Transport ◽  
Rhoptry Protein

ABSTRACTThe survival ofPlasmodiumspp. within the host red blood cell (RBC) depends on the function of a membrane protein complex, termed thePlasmodiumtranslocon of exported proteins (PTEX), that exports certain parasite proteins, collectively referred to as the exportome, across the parasitophorous vacuolar membrane (PVM) that encases the parasite in the host RBC cytoplasm. The core of PTEX consists of three proteins: EXP2, PTEX150, and the HSP101 ATPase; of these three proteins, only EXP2 is a membrane protein. Studying the PTEX-dependent transport of members of the exportome, we discovered that exported proteins, such as ring-infected erythrocyte surface antigen (RESA), failed to be transported in parasites in which the parasite rhoptry protein RON3 was conditionally disrupted. RON3-deficient parasites also failed to develop beyond the ring stage, and glucose uptake was significantly decreased. These findings provide evidence that RON3 influences two translocation functions, namely, transport of the parasite exportome through PTEX and the transport of glucose from the RBC cytoplasm to the parasitophorous vacuolar (PV) space where it can enter the parasite via the hexose transporter (HT) in the parasite plasma membrane.IMPORTANCEThe malarial parasite within the erythrocyte is surrounded by two membranes.Plasmodiumtranslocon of exported proteins (PTEX) in the parasite vacuolar membrane critically transports proteins from the parasite to the erythrocytic cytosol and membrane to create protein infrastructure important for virulence. The components of PTEX are stored within the dense granule, which is secreted from the parasite during invasion. We now describe a protein, RON3, from another invasion organelle, the rhoptry, that is also secreted during invasion. We find that RON3 is required for the protein transport function of the PTEX and for glucose transport from the RBC cytoplasm to the parasite, a function thought to be mediated by PTEX component EXP2.

scholarly journals An improved structural model of the human iron exporter ferroportin. Insight into the role of pathogenic mutations in hereditary hemochromatosis type 4

2017 ◽  
Vol 13 (4) ◽  
Author(s):  
Valentina Tortosa ◽  
Maria Carmela Bonaccorsi di Patti ◽  
Valentina Brandi ◽  
Giovanni Musci ◽  
Fabio Polticelli
Keyword(s):  
Membrane Protein ◽  
Crystal Structures ◽  
Iron Homeostasis ◽  
Structural Model ◽  
Hereditary Hemochromatosis ◽  
Structural Models ◽  
Pivotal Role ◽  
Cellular Iron ◽  
Insight Into

AbstractFerroportin (Fpn) is a membrane protein representing the major cellular iron exporter, essential for metal translocation from cells into plasma. Despite its pivotal role in human iron homeostasis, many questions on Fpn structure and biology remain unanswered. In this work, we present two novel and more reliable structural models of human Fpn (hFpn; inward-facing and outward-facing conformations) obtained using as templates the recently solved crystal structures of a bacterial homologue of hFpn,

14-3-3 proteins in membrane protein transport

2006 ◽  
Vol 387 (9) ◽  
Author(s):  
Thomas Mrowiec ◽  
Blanche Schwappach
Keyword(s):  
Membrane Protein ◽  
Protein Transport

scholarly journals Be Cautious with Crystal Structures of Membrane Proteins or Complexes Prepared in Detergents

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 86 ◽  
Author(s):  
Youzhong Guo
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Crystal Structures ◽  
Structure Determination ◽  
Protein Crystallization ◽  
Energy Coupling ◽  
Careful Examination ◽  
Cubic Phase ◽  
Native Cell ◽  
Membrane Protein Crystallization

Membrane proteins are an important class of macromolecules found in all living organisms and many of them serve as important drug targets. In order to understand their biological and biochemical functions and to exploit them for structure-based drug design, high-resolution and accurate structures of membrane proteins are needed, but are still rarely available, e.g., predominantly from X-ray crystallography, and more recently from single particle cryo-EM — an increasingly powerful tool for membrane protein structure determination. However, while protein-lipid interactions play crucial roles for the structural and functional integrity of membrane proteins, for historical reasons and due to technological limitations, until recently, the primary method for membrane protein crystallization has relied on detergents. Bicelle and lipid cubic phase (LCP) methods have also been used for membrane protein crystallization, but the first step requires detergent extraction of the protein from its native cell membrane. The resulting, crystal structures have been occasionally questioned, but such concerns were generally dismissed as accidents or ignored. However, even a hint of controversy indicates that methodological drawbacks in such structural research may exist. In the absence of caution, structures determined using these methods are often assumed to be correct, which has led to surprising hypotheses for their mechanisms of action. In this communication, several examples of structural studies on membrane proteins or complexes will be discussed: Resistance-Nodulation-Division (RND) family transporters, microbial rhodopsins, Tryptophan-rich Sensory Proteins (TSPO), and Energy-Coupling Factor (ECF) type ABC transporters. These analyses should focus the attention of membrane protein structural biologists on the potential problems in structure determination relying on detergent-based methods. Furthermore, careful examination of membrane proteins in their native cell environments by biochemical and biophysical techniques is warranted, and completely detergent-free systems for membrane protein research are crucially needed.

scholarly journals Molecular architecture of a dynamin adaptor: implications for assembly of mitochondrial fission complexes

2010 ◽  
Vol 191 (6) ◽  
pp. 1127-1139 ◽  
Author(s):  
Sajjan Koirala ◽  
Huyen T. Bui ◽  
Heidi L. Schubert ◽  
Debra M. Eckert ◽  
Christopher P. Hill ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Crystal Structures ◽  
Binding Sites ◽  
Mitochondrial Fission ◽  
Coiled Coil ◽  
Adaptor Proteins ◽  
Molecular Architecture ◽  
Cellular Membranes ◽  
Membrane Scission ◽  
Antiparallel Coiled Coil

Recruitment and assembly of some dynamin-related guanosine triphosphatases depends on adaptor proteins restricted to distinct cellular membranes. The yeast Mdv1 adaptor localizes to mitochondria by binding to the membrane protein Fis1. Subsequent Mdv1 binding to the mitochondrial dynamin Dnm1 stimulates Dnm1 assembly into spirals, which encircle and divide the mitochondrial compartment. In this study, we report that dimeric Mdv1 is joined at its center by a 92-Å antiparallel coiled coil (CC). Modeling of the Fis1–Mdv1 complex using available crystal structures suggests that the Mdv1 CC lies parallel to the bilayer with N termini at opposite ends bound to Fis1 and C-terminal β-propeller domains (Dnm1-binding sites) extending into the cytoplasm. A CC length of appropriate length and sequence is necessary for optimal Mdv1 interaction with Fis1 and Dnm1 and is important for proper Dnm1 assembly before membrane scission. Our results provide a framework for understanding how adaptors act as scaffolds to orient and stabilize the assembly of dynamins on membranes.

Sign in / Sign up

Export Citation Format

Share Document