scholarly journals Dynamic ergosterol- and ceramide-rich domains in the peroxisomal membrane serve as an organizing platform for peroxisome fusion

2005 ◽  
Vol 168 (5) ◽  
pp. 761-773 ◽  
Author(s):  
Tatiana Boukh-Viner ◽  
Tong Guo ◽  
Alex Alexandrian ◽  
André Cerracchio ◽  
Christopher Gregg ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Rafts ◽  
Binding Proteins ◽  
Lateral Movement ◽  
Membrane Bilayer ◽  
Peroxisomal Membrane ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Unusual Distribution ◽  
Key Features

We describe unusual ergosterol- and ceramide-rich (ECR) domains in the membrane of yeast peroxisomes. Several key features of these detergent-resistant domains, including the nature of their sphingolipid constituent and its unusual distribution across the membrane bilayer, clearly distinguish them from well characterized detergent-insoluble lipid rafts in the plasma membrane. A distinct set of peroxisomal proteins, including two ATPases, Pex1p and Pex6p, as well as phosphoinositide- and GTP-binding proteins, transiently associates with the cytosolic face of ECR domains. All of these proteins are essential for the fusion of the immature peroxisomal vesicles P1 and P2, the earliest intermediates in a multistep pathway leading to the formation of mature, metabolically active peroxisomes. Peroxisome fusion depends on the lateral movement of Pex1p, Pex6p, and phosphatidylinositol-4,5-bisphosphate–binding proteins from ECR domains to a detergent-soluble portion of the membrane, followed by their release to the cytosol. Our data suggest a model for the multistep reorganization of the multicomponent peroxisome fusion machinery that transiently associates with ECR domains.

Cellular responses regulated by rho-related small GTP-binding proteins

1993 ◽  
Vol 340 (1293) ◽  
pp. 267-271 ◽  
Keyword(s):  
Plasma Membrane ◽  
Binding Proteins ◽  
Focal Adhesions ◽  
Receptor Activation ◽  
Small Gtpases ◽  
Membrane Receptors ◽  
Phagocytic Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Plasma Membrane Receptors

Rho-related proteins are members of the ras superfamily of small GTP-binding proteins. Their function in fibroblasts has been analysed using microinjection of living cells. Rho appears to link plasma membrane receptors to the assembly of focal adhesions and actin stress fibres. The closely related protein rac, on the other hand, links receptors to the polymerization of actin at the plasma membrane to form membrane ruffles and pinocytotic vesicles. In phagocytic cells, rac has been shown to be required for activation of a membrane-bound NADPH oxidase in response to receptor activation. These systems provide the basis for a working model for the mechanism of action of the rho family of small GTPases.

GTP-Binding proteins in brain and neutrophil are tethered to the plasma membrane via their amino termini

1987 ◽  
Vol 148 (3) ◽  
pp. 1398-1405 ◽  
Author(s):  
Brock Eide ◽  
Peter Gierschik ◽  
Graeme Milligan ◽  
Ian Mullaney ◽  
Cecilia Unson ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding

scholarly journals Regulation of glucose carrier activity by AlCl3 and phospholipase C in fat-cells

1988 ◽  
Vol 256 (2) ◽  
pp. 515-520 ◽  
Author(s):  
B Obermaier-Kusser ◽  
C Mühlbacher ◽  
J Mushack ◽  
E Rattenhuber ◽  
M Fehlmann ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Phospholipase C ◽  
G Protein ◽  
Glucose Transport ◽  
Pertussis Toxin ◽  
Binding Proteins ◽  
Fat Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Glucose Carrier

Recently it was speculated that activation of GTP-binding proteins and of phospholipase is involved in the transmission of a signal from the insulin-receptor kinase to effector systems in the cell. To confirm this hypothesis, we have tested the effect of AlCl3, which has been recently used as an experimental tool to activate GTP-binding proteins, on glucose transport in fat-cells. We found that AlCl3 has a partial insulin-like effect on glucose transport activity (3-O-methylglucose uptake, expressed as % of equilibrium value per 4 s: basal 9.6 +/- 2, AlCl3 29.6 +/- 4, insulin 74.0 +/- 3). The AlCl3 effect is totally blocked by pertussis toxin, whereas the insulin effect was not altered. The effect starts at [AlCl3] greater than 1 fM and reaches its maximum at 0.1 nM. Addition of phospholipase C (PLC; 50 munits/ml) also stimulated glucose transport (maximal 53.0 +/- 5%). Both substances acted faster than insulin itself (maximal values within 1 min for PLC, 2 min for AlCl3 and 5-10 min for insulin). Using the cytochalasin-B-binding assay to determine the effects of AlCl3 and PLC on the distribution of glucose carrier sites in subcellular fractions, we found that their glucose-transport-stimulating effect does not occur through an increase in glucose carrier sites in the plasma-membrane fraction. When PLC was combined with the phorbol ester TPA (12-O-tetradecanoylphorbol 13-acetate), which increases glucose carrier sites in the plasma membrane, an additive effect on glucose transport was found [PLC (50 munits/ml), 53.0 +/- 5%, TPA (1 nM), 17.3 +/- 2%; PLC + TPA, 68.0 +/- 3%]. In conclusion: (1) the data show that AlCl3, probably through activation of a pertussis-toxin-inhibitable G protein, and PLC are able to modulate the intrinsic glucose carrier activity; (2) as pertussis toxin did not modify the effect of insulin, it seems unlikely that the insulin signal on glucose transport involves activation of this specific G protein.

Presence of small GTP-binding proteins in the peroxisomal membrane

1992 ◽  
Vol 1109 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Kristine Verheyden ◽  
Marc Fransen ◽  
Paul P. Van Veldhoven ◽  
Guy P. Mannaerts
Keyword(s):  
Binding Proteins ◽  
Peroxisomal Membrane ◽  
Gtp Binding Proteins ◽  
Gtp Binding

scholarly journals Transport of influenza HA from the trans-Golgi network to the apical surface of MDCK cells permeabilized in their basolateral plasma membranes: energy dependence and involvement of GTP-binding proteins.

1990 ◽  
Vol 111 (6) ◽  
pp. 2893-2908 ◽  
Author(s):  
D Gravotta ◽  
M Adesnik ◽  
D D Sabatini
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Binding Proteins ◽  
Mdck Cells ◽  
Basolateral Membrane ◽  
Apical Surface ◽  
Gtp Binding Proteins ◽  
Trans Golgi Network ◽  
Gtp Binding ◽  
Golgi Network

A procedure employing streptolysin O to effect the selective permeabilization of either the apical or basolateral plasma membrane domains of MDCK cell monolayers grown on a filter support was developed which permeabilizes the entire monolayer, leaves the opposite cell surface domain intact, and does not abolish the integrity of the tight junctions. This procedure renders the cell interior accessible to exogenous macromolecules and impermeant reagents, permitting the examination of their effects on membrane protein transport to the intact surface. The last stages of the transport of the influenza virus hemagglutinin (HA) to the apical surface were studied in pulse-labeled, virus-infected MDCK cells that were incubated at 19.5 degrees C for 90 min to accumulate newly synthesized HA in the trans-Golgi network (TGN), before raising the temperature to 35 degrees C to allow synchronized transport to the plasma membrane. In cells permeabilized immediately after the cold block, 50% of the intracellular HA molecules were subsequently delivered to the apical surface. This transport was dependent on the presence of an exogenous ATP supply and was markedly inhibited by the addition of GTP-gamma-S at the time of permeabilization. On the other hand, the GTP analogue had no effect when it was added to cells that, after the cold block, were incubated for 15 min at 35 degrees C before permeabilization, even though at this time most HA molecules were still intracellular and their appearance at the cell surface was largely dependent on exogenous ATP. These findings indicate that GTP-binding proteins are involved in the constitutive process that effects vesicular transport from the TGN to the plasma membrane and that they are charged early in this process. Transport of HA to the cell surface could be made dependent on the addition of exogenous cytosol when, after permeabilization, cells were washed to remove endogenous cytosolic components. This opens the way towards the identification of cell components that mediate the sorting of apical and basolateral membrane components in the TGN and their polarized delivery to the cell surface.

Sign in / Sign up

Export Citation Format

Share Document