14-3-3 proteins in membrane protein transport

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

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 Mutants in three novel complementation groups inhibit membrane protein insertion into and soluble protein translocation across the endoplasmic reticulum membrane of Saccharomyces cerevisiae.

1992 ◽  
Vol 116 (3) ◽  
pp. 597-604 ◽  
Author(s):  
N Green ◽  
H Fang ◽  
P Walter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Membrane Protein ◽  
Protein Transport ◽  
Protein Translocation ◽  
Soluble Proteins ◽  
Endoplasmic Reticulum Membrane ◽  
Protein Insertion ◽  
Membrane Protein Insertion ◽  
Complementation Groups ◽  
Er Membrane

We have isolated mutants that inhibit membrane protein insertion into the ER membrane of Saccharomyces cerevisiae. The mutants were contained in three complementation groups, which we have named SEC70, SEC71, and SEC72. The mutants also inhibited the translocation of soluble proteins into the lumen of the ER, indicating that they pleiotropically affect protein transport across and insertion into the ER membrane. Surprisingly, the mutants inhibited the translocation and insertion of different proteins to drastically different degrees. We have also shown that mutations in SEC61 and SEC63, which were previously isolated as mutants inhibiting the translocation of soluble proteins, also affect the insertion of membrane proteins into the ER. Taken together our data indicate that the process of protein translocation across the ER membrane involves a much larger number of gene products than previously appreciated. Moreover, different translocation substrates appear to have different requirements for components of the cellular targeting and translocation apparatus.

scholarly journals Sec12p-dependent membrane binding of the small GTP-binding protein Sar1p promotes formation of transport vesicles from the ER.

1991 ◽  
Vol 114 (4) ◽  
pp. 663-670 ◽  
Author(s):  
C d'Enfert ◽  
L J Wuestehube ◽  
T Lila ◽  
R Schekman
Keyword(s):  
Membrane Protein ◽  
Protein Transport ◽  
Binding Protein ◽  
Integral Membrane Protein ◽  
Gtp Binding Protein ◽  
Vesicle Budding ◽  
Gtp Binding ◽  
Transport Vesicles

Sec12p is an integral membrane protein required in vivo and in vitro for the formation of transport vesicles generated from the ER. Vesicle budding and protein transport from ER membranes containing normal levels of Sec12p is inhibited in vitro by addition of microsomes isolated from a Sec12p-overproducing strain. Inhibition is attributable to titration of a limiting cytosolic protein. This limitation is overcome by addition of a highly enriched fraction of soluble Sar1p, a small GTP-binding protein, shown previously to be essential for protein transport from the ER and whose gene has been shown to interact genetically with sec12. Furthermore, Sar1p binding to isolated membranes is enhanced at elevated levels of Sec12p. Sar1p-Sec12p interaction may regulate the initiation of vesicle budding from the ER.

scholarly journals Transmembrane movement of a water-soluble analogue of mannosylphosphoryldolichol is mediated by an endoplasmic reticulum protein.

1995 ◽  
Vol 130 (3) ◽  
pp. 529-536 ◽  
Author(s):  
J S Rush ◽  
C J Waechter
Keyword(s):  
Membrane Protein ◽  
Mouse Liver ◽  
Protein Transport ◽  
Micrococcus Luteus ◽  
Protein S ◽  
Water Soluble ◽  
Permeability Barrier ◽  
Cytoplasmic Face ◽  
Endoplasmic Reticulum Protein ◽  
Luminal Compartment

Based on topological studies mannosylphosphoryldolichol (Man-P-Dol) is synthesized on the cytoplasmic face of the RER, but functions as a mannosyl donor in Glc3Man9GlcNAc2-P-P-dolichol biosynthesis after the mannosyl-phosphoryl headgroup diffuses transversely to the luminal compartment. The transport of mannosylphosphorylcitronellol (Man-P-Cit), a water-soluble analogue of Man-P-Dol, by microsomal vesicles from mouse liver, has been investigated as a potential experimental approach to determine if a membrane protein(s) mediates the transbilayer movement of Man-P-Dol. For these studies beta-[3H]Man-P-Cit was synthesized enzymatically with a partially purified preparation of Man-P-undecaprenol synthase from Micrococcus luteus. The uptake of the radiolabeled water-soluble analogue was found to be (a) time dependent; (b) stereoselective; (c) dependent on an intact permeability barrier; (d) saturable; (e) protease-sensitive; and (f) highest in ER-enriched vesicles relative to Golgi complex-enriched vesicles and intact mitochondria. Consistent with the involvement of a membrane protein, the analogue did not enter synthetic phosphatidylcholine-liposomes. [3H]Man-P-Cit also was not transported by human erythrocytes. These results indicate that the transport of Man-P-Cit by sealed microsomal vesicles from mouse liver is mediated by a membrane protein transport system. It is possible that the same membrane protein(s) participates in the transbilayer movement of Man-P-Dol in the ER.

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