scholarly journals Connecting the dots: combined control of endocytic recycling and degradation

2020 ◽  
Vol 48 (6) ◽  
pp. 2377-2386
Author(s):  
Ewan MacDonald ◽  
Bryan Savage ◽  
Tobias Zech
Keyword(s):  
Plasma Membrane ◽  
Coated Vesicles ◽  
Endocytic Recycling ◽  
Combined Control ◽  
Recent Developments ◽  
Membrane Bound ◽  
Connecting The Dots

Endocytosis is an essential process where proteins and lipids are internalised from the plasma membrane in membrane-bound carriers, such as clathrin-coated vesicles. Once internalised into the cell these vesicles fuse with the endocytic network where their contents are sorted towards degradation in the lysosome or recycling to their origin. Initially, it was thought that cargo recycling is a passive process, but in recent years the identification and characterisation of specialised recycling complexes has established a hitherto unthought-of level of complexity that actively opposes degradation. This review will summarise recent developments regarding the composition and regulation of the recycling machineries and their relationship with the degradative pathways of the endosome.

scholarly journals Very Cool Clathrin

2005 ◽  
Vol 13 (6) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Plasma Membrane ◽  
Coated Vesicles ◽  
Membrane Bilayer ◽  
Membrane Bound ◽  
Membranous Component

Clathrin-coated vesicles are the shuttle containers within cells. The vesicles carry lipids and proteins between membrane-bound compartments. Clathrin forms a cage-like structure around the membrane-bound vesicle that is pinched off from the plasma membrane (in endocytosis) or a membranous component of the cytoplasm. Clathrin recruits cargo that is within a vesicle through intermediary proteins known as adaptors that help select membrane-anchored protein and form an interface between the clathrin cage and the membrane bilayer.

scholarly journals Plasma membrane coat and a coated vesicle-associated reticulum of membranes: their structure and possible interrelationship in Chara corallina.

1984 ◽  
Vol 98 (4) ◽  
pp. 1537-1545 ◽  
Author(s):  
T C Pesacreta ◽  
W J Lucas
Keyword(s):  
Plasma Membrane ◽  
Chara Corallina ◽  
Peripheral Region ◽  
Coated Vesicles ◽  
Coated Vesicle ◽  
Structural Components ◽  
The Core ◽  
Membrane Bound ◽  
Zinc Iodide ◽  
Coat Material

Primary fixation with buffered glutaraldehyde plus 2.0 mM CaCl2 and 0.1% tannic acid results in the preservation of certain portions of the plasma membrane coat of Chara when seen with the electron microscope. Such a coat is not observable after fixation with glutaraldehyde alone. The coat appears to be present on all the above ground, vegetative cells of the male plant. Within complex invaginations of the plasma membrane, which are known as charasomes, the coat has two structural components, a central core that is either tubular or solid and a fibrous or granular peripheral region that surrounds the core. The coat material appears to be at least partially derived, via exocytosis, from the contents of single membrane-bound organelles known as glycosomes. Glycosomes seem to originate from within an assemblage of membranes and coated vesicles that can be described, in purely structural terms, as a partially coated reticulum. Such a reticulum is distinguishable from Golgi stacks because the reticulum (a) is not composed of stacked membranes, (b) is extensively involved with large, clearly detailed coated vesicles and coated invaginations, (c) is closely associated with glycosomes, and (d) is only slightly stained by the zinc-iodide-osmium tetraoxide reagent.

Exterior and Interior Events in Early Stage of Thrombin-induced Platelet Aggregation

1977 ◽  
Vol 38 (03) ◽  
pp. 0630-0639 ◽  
Author(s):  
Shuichi Hashimoto ◽  
Sachiko Shibata ◽  
Bonro Kobayashi
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Plasma Membrane ◽  
Platelet Aggregation ◽  
Early Stage ◽  
Adenyl Cyclase ◽  
Cellular Component ◽  
Primary Event ◽  
Rabbit Platelets ◽  
Membrane Bound

SummaryTreatment of washed rabbit platelets with 1 u/ml of thrombin at 37° C resulted in a disappearance from platelets of a protein with 250,000 dalton molecular weight which was shown to be originated from plasma membrane. Parallel loss of adenyl cyclase was noted, and both reactions were complete within 30 sec. From the patterns of disc electrophoretograms, the importance of quick suppression of thrombin action in demonstrating the primary event was stressed.Thrombin induced an apparent activation of membrane bound phosphodiesterase. This reaction was also complete within 30 sec. The cellular component which contained the enzyme activity was distinct from plasma membrane. Soluble phosphodiesterase was not influenced by thrombin at all.These reactions required intact platelet cells to react with thrombin, and no reaction was detected when subcellular preparations were treated with thrombin.Possibility of collaboration of changes in externally located synthetic enzyme with those in internally located degrading enzyme in the early phase of thrombin action on platelets was suggested.

scholarly journals PROBLEMS ASSOCIATED WITH THE DEMONSTRATION BY LEAD METHODS OF ADENOSINE TRIPHOSPHATASE ACTIVITY IN RESIDENT PERITONEAL MACROPHAGES AND EXUDATE MONOCYTES OF THE GUINEA PIG

1973 ◽  
Vol 21 (5) ◽  
pp. 488-498 ◽  
Author(s):  
R. E. POELMANN ◽  
W. T. DAEMS ◽  
E. J. VAN LOHUIZEN
Keyword(s):  
Plasma Membrane ◽  
Guinea Pig ◽  
Microscopic Study ◽  
Heterogeneous Nucleation ◽  
Adenosine Triphosphatase ◽  
Peritoneal Macrophages ◽  
Electron Microscopic ◽  
Adenosine Triphosphatase Activity ◽  
Eosinophilic Granulocytes ◽  
Membrane Bound

This cytochemical and electron microscopic study on peritoneal macrophages of the guinea pig has raised doubts concerning the validity of lead methods for the demonstration of plasma membrane-bound adenosine triphosphatase activity. The problems encountered are inherent in the use of lead ions as a capture reagent. The nonenzymatically formed precipitates reflect sites of heterogeneous nucleation specific for certain kinds of cells, e.g., resident peritoneal macrophages, eosinophilic granulocytes and, to a lesser degree, exudate monocytes. This type of precipitation is also catalyzed on the surface of nonbiologic matrices such as latex particles. Enzymatic processes may well occur, but they cannot be distinguished from nonenzymatic processes.

scholarly journals A constitutive, plasma-membrane bound β-glucosidase inTrichoderma reesei

1986 ◽  
Vol 34 (3) ◽  
pp. 291-295 ◽  
Author(s):  
Claudio Umile ◽  
Christian P. Kubicek
Keyword(s):  
Plasma Membrane ◽  
Membrane Bound

scholarly journals A novel adenylylation process in liver plasma membrane-bound proteins

1990 ◽  
Vol 265 (33) ◽  
pp. 20653-20661
Author(s):  
E San José ◽  
A Benguría ◽  
A Villalobo
Keyword(s):  
Plasma Membrane ◽  
Liver Plasma Membrane ◽  
Membrane Bound

The heterotrimeric Gi(3) protein acts in slow but not in fast exocytosis of rat melanotrophs

1999 ◽  
Vol 112 (22) ◽  
pp. 4143-4150 ◽  
Author(s):  
M. Kreft ◽  
S. Gasman ◽  
S. Chasserot-Golaz ◽  
V. Kuster ◽  
M. Rupnik ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
G Proteins ◽  
Flash Photolysis ◽  
Secretory Granules ◽  
Secretory Activity ◽  
Α Subunit ◽  
Capacitance Measurements ◽  
Regulated Secretion ◽  
Kinetic Component ◽  
Membrane Bound

Besides having a role in signal transduction some trimeric G-proteins may be involved in a late stage of exocytosis. Using immunocytochemistry and confocal microscopy we found that Gi(3)-protein resides mainly in the plasma membrane, whereas Gi(1/2-)protein is preferentially associated with secretory granules. To study the function of trimeric Gi(3)- and Gi(1/2)-proteins, secretory responses in single rat melanotrophs were monitored by patch-clamp membrane capacitance measurements. We report here that mastoparan, an activator of trimeric G-proteins, enhances calcium-induced secretory activity in rat melanotrophs. The introduction of synthetic peptides corresponding to the C-terminal domain of the (α)-subunit of Gi(3)- and Gi(1/2)-proteins indicated that Gi(3)peptide specifically blocked the mastoparan-stimulated secretory activity, which indicates an involvement of a trimeric Gi(3)-protein in mastoparan-stimulated secretory activity. Flash photolysis of caged Ca(2+)-elicited biphasic capacitance increases consisting of a fast and a slower component. Injection of anti-Gi(3) antibodies selectively inhibited the slow but not the fast component of secretory activity in rat melanotrophs. We propose that the plasma membrane-bound Gi(3)-protein may be involved in regulated secretion by specifically controlling the slower kinetic component of exocytosis.

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