scholarly journals Agrin-Induced Phosphorylation of the Acetylcholine Receptor Regulates Cytoskeletal Anchoring and Clustering

2001 ◽  
Vol 153 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Lúcia S. Borges ◽  
Michael Ferns
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Acetylcholine Receptor ◽  
Membrane Surface ◽  
Β Subunit ◽  
Wild Type ◽  
Receptor Localization ◽  
Muscle Specific Kinase ◽  
Type Receptor ◽  
Plasma Membrane Surface

At the developing neuromuscular junction, a motoneuron-derived factor called agrin signals through the muscle-specific kinase receptor to induce postsynaptic aggregation of the acetylcholine receptor (AChR). The agrin signaling pathway involves tyrosine phosphorylation of the AChR β subunit, and we have tested its role in receptor localization by expressing tagged, tyrosine-minus forms of the β subunit in mouse Sol8 myotubes. We find that agrin-induced phosphorylation of the β subunit occurs only on cell surface AChR, and that AChR-containing tyrosine-minus β subunit is targeted normally to the plasma membrane. Surface AChR that is tyrosine phosphorylated is less detergent extractable than nonphosphorylated AChR, indicating that it is preferentially linked to the cytoskeleton. Consistent with this, we find that agrin treatment reduces the detergent extractability of AChR that contains tagged wild-type β subunit but not tyrosine-minus β subunit. In addition, agrin-induced clustering of AChR containing tyrosine-minus β subunit is reduced in comparison to wild-type receptor. Thus, we find that agrin-induced phosphorylation of AChR β subunit regulates cytoskeletal anchoring and contributes to the clustering of the AChR, and this is likely to play an important role in the postsynaptic localization of the receptor at the developing synapse.

In Vivo Effects of Ozone on Rat Alveolar Macrophage Plasma Membrane Surface Sulfhydryl Groups

1988 ◽  
Vol 529 (1 Fourth Colloq) ◽  
pp. 73-74
Author(s):  
J. E. RYER ◽  
G. WITZ ◽  
B. D. GOLDSTEIN ◽  
M. A. AMORUSO
Keyword(s):  
Plasma Membrane ◽  
Alveolar Macrophage ◽  
Membrane Surface ◽  
Sulfhydryl Groups ◽  
In Vivo Effects ◽  
Plasma Membrane Surface

scholarly journals Paracrystalline arrays of membrane-to-membrane cross bridges associated with the inner surface of plasma membrane

1978 ◽  
Vol 77 (2) ◽  
pp. 323-328 ◽  
Author(s):  
WW Franke ◽  
C Grund ◽  
E Schmid ◽  
E Mandelkow
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Cultured Cells ◽  
Membrane Surface ◽  
Hexagonal Lattice ◽  
Interparticle Distance ◽  
Macromolecular Complexes ◽  
Inner Surface ◽  
Cross Bridges ◽  
Plasma Membrane Surface

In cultured cells of the rat kangaroo PtK2 line, veils of the cell surface were observed which consisted of only plasma membrane and paracrystalline arrays of membrane-associated particles sandwiched in between. These membrane-to-membrane cross-bridging 9-to 11-nm wide particles were somewhat coumellar-shaped and were arranged on a hexagonal lattice with an interparticle distance of 16nm. At higher magnification, they revealed an unstained core, thus suggesting a ringlike substructure. Similar arrays of paracrystal-containing veils, which were rather variable in size and frequency, were also observed in other cultured cells. It is hypothesized that these paracrystals represent protein macromolecular complexes associated with the inner plasma membrane surface which crystallize when plasma membranes come into close intracellular contact and other components of the subsurface network are removed.

scholarly journals Tetherin is an exosomal tether

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
James R Edgar ◽  
Paul T Manna ◽  
Shinichi Nishimura ◽  
George Banting ◽  
Margaret S Robinson
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Short Range ◽  
Wild Type ◽  
Concomitant Increase ◽  
Gpi Anchor ◽  
Fold Reduction ◽  
Cell Metastasis ◽  
Health And Disease ◽  
Prion Transmission

Exosomes are extracellular vesicles that are released when endosomes fuse with the plasma membrane. They have been implicated in various functions in both health and disease, including intercellular communication, antigen presentation, prion transmission, and tumour cell metastasis. Here we show that inactivating the vacuolar ATPase in HeLa cells causes a dramatic increase in the production of exosomes, which display endocytosed tracers, cholesterol, and CD63. The exosomes remain clustered on the cell surface, similar to retroviruses, which are attached to the plasma membrane by tetherin. To determine whether tetherin also attaches exosomes, we knocked it out and found a 4-fold reduction in plasma membrane-associated exosomes, with a concomitant increase in exosomes discharged into the medium. This phenotype could be rescued by wild-type tetherin but not tetherin lacking its GPI anchor. We propose that tetherin may play a key role in exosome fate, determining whether they participate in long-range or short-range interactions.

Plasma membrane delivery of the gastric H,K-ATPase: the role of β-subunit glycosylation

2003 ◽  
Vol 285 (4) ◽  
pp. C968-C976 ◽  
Author(s):  
O. Vagin ◽  
S. Denevich ◽  
G. Sachs
Keyword(s):  
Plasma Membrane ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Glycosylation Site ◽  
Β Subunit ◽  
Wild Type ◽  
Α Subunit ◽  
Hek 293 ◽  
Glycosylation Sites ◽  
293 Cells

The factors determining trafficking of the gastric H,K-ATPase to the apical membrane remain elusive. To identify such determinants in the gastric H,K-ATPase, fusion proteins of yellow fluorescent protein (YFP) and the gastric H,K-ATPase β-subunit (YFP-β) and cyan fluorescent protein (CFP) and the gastric H,K-ATPase α-subunit (CFP-α) were expressed in HEK-293 cells. Then plasma membrane delivery of wild-type CFP-α, wild-type YFP-β, and YFP-β mutants lacking one or two of the seven β-subunit glycosylation sites was determined using confocal microscopy and surface biotinylation. Expression of the wild-type YFP-β resulted in the plasma membrane localization of the protein, whereas the expressed CFP-α was retained intracellularly. When coexpressed, both CFP-α and YFP-β were delivered to the plasma membrane. Removing each of the seven glycosylation sites, except the second one, from the extracellular loop of YFP-β prevented plasma membrane delivery of the protein. Only the mutant lacking the second glycosylation site (Asn103Gln) was localized both intracellularly and on the plasma membrane. A double mutant lacking the first (Asn99Gln) and the second (Asn103Gln) glycosylation sites displayed intracellular accumulation of the protein. Therefore, six of the seven glycosylation sites in the β-subunit are essential for the plasma membrane delivery of the β-subunit of the gastric H,K-ATPase, whereas the second glycosylation site (Asn103), which is not conserved among the β-subunits from different species, is not critical for plasma delivery of the protein.

The influence of differentiation-inducing agents on plasma membrane surface characteristics of THP-1 cells

2011 ◽  
Vol 5 (2) ◽  
pp. 135-142
Author(s):  
S. V. Zubova ◽  
D. S. Kabanov ◽  
A. Yu. Ivanov ◽  
E. V. Voloshina ◽  
I. I. Proskuryakov ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Surface ◽  
Surface Characteristics ◽  
Plasma Membrane Surface
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