Compartmentation and topology of glucosylceramide synthesis

2000 ◽  
Vol 28 (6) ◽  
pp. 748-750 ◽  
Author(s):  
J. L. Cantatore ◽  
S. M. Murphy ◽  
D. V. Lynch
Keyword(s):  
Plasma Membrane ◽  
Proteolytic Enzymes ◽  
Glucosylceramide Synthase ◽  
Steryl Glucoside ◽  
And Topology ◽  
Cytosolic Side

Evidence is presented supporting a model for glucosylceramide formation on the apoplastic side of the plasma membrane in plants. Glucosylceramide synthase and sterol glucosyltransferase were both localized to the plasma membrane. Whereas sterol glucosylation was sensitive to proteolytic enzymes, ceramide glucosylation was not. These results are consistent with our model in which steryl glucoside is synthesized on the cytosolic side of the membrane and then translocated across the membrane where it donates glucose to ceramide.

scholarly journals Plasma membrane damage causes NLRP3 activation and pyroptosis during Mycobacterium tuberculosis infection

2019 ◽  
Author(s):  
Kai S. Beckwith ◽  
Marianne S. Beckwith ◽  
Sindre Ullmann ◽  
Ragnhild Sætra ◽  
Haelin Kim ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Plasma Membrane ◽  
Membrane Damage ◽  
Common Mechanism ◽  
Mycobacterium Tuberculosis Infection ◽  
Plasma Membrane Damage ◽  
Cytosolic Side ◽  
Infected Cells ◽  
Mediated Contact ◽  
Spread Of Infection

AbstractMycobacterium tuberculosis (Mtb) is a major global health problem and causes extensive cytotoxicity in patient cells and tissues. Here we define an NLRP3, caspase-1 and gasdermin D-mediated pathway to pyroptosis in human monocytes following exposure to Mtb. We demonstrate an ESX-1 mediated, contact-induced plasma membrane (PM) damage response that occurs during phagocytosis or from the cytosolic side of the PM after phagosomal rupture in Mtb infected cells. This PM injury in turn causes K+ efflux and activation of NLRP3 dependent IL-1β release and pyroptosis, facilitating the spread of Mtb to neighbouring cells. Further we reveal a dynamic interplay of pyroptosis with ESCRT-mediated PM repair. Collectively, these findings reveal a novel mechanism for pyroptosis and spread of infection acting through dual PM disturbances both during and after phagocytosis. We also highlight dual PM damage as a common mechanism utilized by other NLRP3 activators that have previously been shown to act through lysosomal damage.Graphical abstract

scholarly journals Anchorage-dependent surface distribution and partition during freeze-fracture of viral transmembrane glycoproteins.

1990 ◽  
Vol 38 (10) ◽  
pp. 1421-1426 ◽  
Author(s):  
M R Torrisi ◽  
A Pavan ◽  
L V Lotti ◽  
G Migliaccio ◽  
M C Pascale ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Sindbis Virus ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Viral Proteins ◽  
Low Ph ◽  
Surface Distribution ◽  
Transfected Cells ◽  
Cytosolic Side ◽  
Infected Cells

We have compared in the same cell type the surface distribution and partition in freeze-fractured plasma membranes of Sindbis virus glycoproteins in three different situations: (i) in permanently transformed cells that express the glycoproteins as the only viral product; (ii) in cells in which prebound viruses were forced to fuse with the plasma membrane by low pH treatment; (iii) in virus-infected cells. We report here that the viral proteins expressed on the surface of transfected cells show a uniform and unclustered distribution; conversely, in Sindbis virus-infected cells they appear clustered, regionally distributed, and always associated with budding viruses (i.e., interacting with the nucleocapsid on the cytosolic side of the membrane). Furthermore, the viral proteins expressed on transfected cells or implanted by low pH-mediated fusion partition during freeze-fracture with the exoplasmic faces of the cell plasma membranes, whereas an opposite partition is observed in infected cells. These results strongly suggest that in infected cells the clustering and the partition with the protoplasmic faces of the plasma membrane depend only on the strong "anchorage" of the glycoproteins to the nucleocapsid.

scholarly journals Carbonic Anhydrase II Associated with Plasma Membrane in a Human Pancreatic Duct Cell Line (CAPAN-1)

2001 ◽  
Vol 49 (8) ◽  
pp. 1045-1053 ◽  
Author(s):  
Laetitia Alvarez ◽  
Marjorie Fanjul ◽  
Nicholas Carter ◽  
Etienne Hollande
Keyword(s):  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Pancreatic Duct ◽  
Subcellular Distribution ◽  
Plasma Membranes ◽  
Brefeldin A ◽  
Duct Cell ◽  
Carbonic Anhydrase Ii ◽  
Apical Plasma Membrane ◽  
Cytosolic Side

The subcellular distribution of carbonic anhydrase II, either throughout the cytosol or in the cytoplasm close to the apical plasma membrane or vesicular compartments, suggests that this enzyme may have different roles in the regulation of pH in intra- or extracellular compartments. To throw more light on the role of pancreatic carbonic anhydrase II, we examined its expression and subcellular distribution in Capan-1 cells. Immunocytochemical analysis by light, confocal, and electron microscopy, as well as immunoblotting of cell homogenates or purified plasma membranes, was performed. A carbonic anhydrase II of 29 kD associated by weak bonds to the inner leaflet of apical plasma membranes of polarized cells was detected. This enzyme was co-localized with markers of Golgi compartments. Moreover, the defect of its targeting to apical plasma membranes in cells treated with brefeldin A was indicative of its transport by the Golgi apparatus. We show here that a carbonic anhydrase II is associated with the inner leaflet of apical plasma membranes and with the cytosolic side of the endomembranes of human cancerous pancreatic duct cells (Capan-1). These observations point to a role for this enzyme in the regulation of intra- and extracellular pH. (J Histochem Cytochem 49:1045–1053, 2001)

scholarly journals Structure, amphipathy, and topology of the membrane-proximal helix 8 influence apelin receptor plasma membrane localization

2019 ◽  
Vol 1861 (11) ◽  
pp. 183036 ◽  
Author(s):  
Aditya Pandey ◽  
Danielle M. LeBlanc ◽  
Hirendrasinh B. Parmar ◽  
Trần Thanh Tâm Phạm ◽  
Muzaddid Sarker ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Localization ◽  
Plasma Membrane Localization ◽  
And Topology ◽  
Apelin Receptor

scholarly journals Activation of a latent nuclear localization signal in the NH2 terminus of γ-ENaC initiates feedback regulation of channel activity

2010 ◽  
Vol 298 (5) ◽  
pp. F1188-F1196
Author(s):  
Elena Mironova ◽  
James D. Stockand
Keyword(s):  
Plasma Membrane ◽  
Nuclear Localization ◽  
Transmembrane Domain ◽  
Proteolytic Enzymes ◽  
Feedback Regulation ◽  
Negative Regulation ◽  
Dependent Manner ◽  
Open Probability ◽  
Nuclear Localization Signals ◽  
Primary Amino

Proteolytic enzymes cleave the epithelial Na+ channel (ENaC) at several positions releasing, in part, the NH2 terminus of the γ-subunit. Cleavage increases ENaC activity by increasing open probability; however, the role of polypeptides cleaved from the channel core remains unclear. We find that the cytosolic NH2 terminus of γ-ENaC unexpectedly targets to the nucleus being particularly strong in nucleoli. In contrast, the cytosolic COOH terminus targets to the cytoplasm and plasma membrane in a manner similar to full-length subunits. Targeting of the cytosolic NH2 terminus of γ-ENaC to the nucleus has functional consequences for coexpression of eGFP-fusion proteins containing this segment of the channel, but not the COOH terminus, decrease ENaC activity in a dose-dependent manner. The mechanism of this negative regulation is associated with a decrease in the functional half-life of ENaC at the plasma membrane. Inspection of the primary amino acid sequence of γ-ENaC reveals possible nuclear localization signals (NLS) conserved at the extreme NH2 terminus and just preceding the first transmembrane domain. Disruption of the putative NLS preceding the first transmembrane domain in γ-ENaC but not that at the extreme NH2 terminus abolishes both targeting to the nucleus and negative regulation of ENaC activity. These findings are consistent with the release of the NH2 terminus of γ-ENaC following cleavage being functionally important for signaling to the nucleus in a manner similar to Notch signaling and release of the cytosolic COOH-terminal tail of polycystin-1.

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