Particle Movement in Heliozoan Axopods Associated with Lateral Displacement of H ighly Ordered Membrane Domains

1976 ◽  
Vol 31 (3-4) ◽  
pp. 190-194 ◽  
Author(s):  
Christian F. Bardele
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Fusion ◽  
Lateral Displacement ◽  
Freeze Fracture ◽  
Motive Force ◽  
Membrane Domains ◽  
Particle Movement ◽  
Peripheral Membrane Proteins

Abstract Freeze-fracture studies reveal that extrusive organelles displaying saltatory particle movements in centrohelidian axopod are attached to highly ordered domains within the plasma membrane. It is postulated that the motive force for lateral displacement of these membrane domains with the adhering organelle is located immediately underneath the plasma membrane being either part of the peripheral membrane proteins or attached filaments alined parallel to the axopodial micro­ tubules. The attachment domain is interpreted organelle discharge by membrane fusion.

Membrane changes associated with mucus production by intestinal goblet cells

1978 ◽  
Vol 33 (1) ◽  
pp. 301-316
Author(s):  
J.G. Swift ◽  
T.M. Mukherjee
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Fusion ◽  
Thin Section ◽  
Structural Organization ◽  
Freeze Fracture ◽  
Goblet Cells ◽  
Mucus Production ◽  
Membrane Reorganization ◽  
Membrane Changes

Changes in the structural organization of membranes of mucous bodies and the plasma membrane that occur during mucus production in goblet cells of rat rectum have been studied by thin-section and freeze-fracture techniques. Immature mucous bodies are bounded by a trilaminar membrane and fracture faces of the membrane have randomly distributed intramembrane particles. During maturation, mucous bodies become packed tightly together and changes in the structure of their membranes include (1) fusion of apposing membranes of adjacent bodies to form a pentalaminar structure, (2) a reduction in the density of particles on membrane fracture faces, and (3) exclusion of particles from regions of membrane apposition. Some trilaminar membranes of mucous bodies fuse with the lumenal plasma membrane to form a pentalaminar structure. Sites of apposition between mucous body membranes and the lumenal plasma membrane are seen as particle-cleared bulges on fracture faces of the plasma membrane. Our results indicate that membrane reorganization associated with mucous production in goblet cells includes a reduction and redistribution of some membrane proteins and that membrane fusion occurs between portions of membranes from which proteins have been displaced.

scholarly journals Phagocytosis of bacteria by polymorphonuclear leukocytes: a freeze-fracture, scanning electron microscope, and thin-section investigation of membrane structure

1978 ◽  
Vol 76 (1) ◽  
pp. 158-174 ◽  
Author(s):  
PL Moore ◽  
HL Bank ◽  
NT Brissie ◽  
SS Spicer
Keyword(s):  
Plasma Membrane ◽  
Electron Microscope ◽  
Membrane Fusion ◽  
Thin Section ◽  
Membrane Structure ◽  
Freeze Fracture ◽  
Vacuole Membrane ◽  
Attachment Sites ◽  
Pmn Leukocytes ◽  
Scanning Electron

The changes in membrane structure of rabbit polymorphonuclear (PMN) leukocytes during bacterial phagocytosis was investigated with scanning electron microscope (SEM), thin-section, and freeze-fracture techniques. SEM observations of bacterial attachment sites showed the involvement of limited areas of PMN membrane surface (0.01-0.25μm(2)). Frequently, these areas of attachment were located on membrane extensions. The membrane extensions were present before, during, and after the engulfment of bacteria, but were diminished in size after bacterial engulfment. In general, the results obtained with SEM and thin-section techniques aided in the interpretation of the three-dimensional freeze-fracture replicas. Freeze-fracture results revealed the PMN leukocytes had two fracture faces as determined by the relative density of intramembranous particles (IMP). Membranous extensions of the plasma membrane, lysosomes, and phagocytic vacuoles contained IMP's with a distribution and density similar to those of the plasma membrane. During phagocytosis, IMPs within the plasma membrane did not undergo a massive aggregation. In fact, structural changes within the membranes were infrequent and localized to regions such as the attachment sites of bacteria, the fusion sites on the plasma membrane, and small scale changes in the phagocytic vacuole membrane during membrane fusion. During the formation of the phagocytic vacuole, the IMPs of the plasma membrane appeared to move in with the lipid bilayer while maintaining a distribution and density of IMPs similar to those of the plasma membranes. Occasionally, IMPs were aligned to linear arrays within phagocytic vacuole membranes. This alignment might be due to an interaction with linearly arranged motile structures on the side of the phagocytic vacuole membranes. IMP-free regions were observed after fusion of lysosomes with the phagocytic vacuoles or plasma membrane. These IMP-free areas probably represent sites where membrane fusion occurred between lysosomal membrane and phagocytic vacuole membrane or plasma membrane. Highly symmetrical patterns of IMPs were not observed during lysosomal membrane fusion.

scholarly journals Plasma Membrane Protein Nce102 Modulates Morphology and Function of the Yeast Vacuole

Biomolecules ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1476
Author(s):  
Katarina Vaskovicova ◽  
Petra Vesela ◽  
Jakub Zahumensky ◽  
Dagmar Folkova ◽  
Maria Balazova ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Vacuolar Membrane ◽  
Yeast Culture ◽  
Membrane Domains ◽  
Biological Functions ◽  
Plasma Membrane Protein ◽  
Cell Architecture ◽  
And Function

Membrane proteins are targeted not only to specific membranes in the cell architecture, but also to distinct lateral microdomains within individual membranes to properly execute their biological functions. Yeast tetraspan protein Nce102 has been shown to migrate between such microdomains within the plasma membrane in response to an acute drop in sphingolipid levels. Combining microscopy and biochemistry methods, we show that upon gradual ageing of a yeast culture, when sphingolipid demand increases, Nce102 migrates from the plasma membrane to the vacuole. Instead of being targeted for degradation it localizes to V-ATPase-poor, i.e., ergosterol-enriched, domains of the vacuolar membrane, analogous to its plasma membrane localization. We discovered that, together with its homologue Fhn1, Nce102 modulates vacuolar morphology, dynamics, and physiology. Specifically, the fusing of vacuoles, accompanying a switch of fermenting yeast culture to respiration, is retarded in the strain missing both proteins. Furthermore, the absence of either causes an enlargement of ergosterol-rich vacuolar membrane domains, while the vacuoles themselves become smaller. Our results clearly show decreased stability of the V-ATPase in the absence of either Nce102 or Fhn1, a possible result of the disruption of normal microdomain morphology of the vacuolar membrane. Therefore, the functionality of the vacuole as a whole might be compromised in these cells.

scholarly journals Control of membrane fusion in exocytosis. Physiological studies on a Paramecium mutant blocked in the final step of the trichocyst extrusion process.

1980 ◽  
Vol 85 (2) ◽  
pp. 213-227 ◽  
Author(s):  
J Beisson ◽  
J Cohen ◽  
M Lefort-Tran ◽  
M Pouphile ◽  
M Rossignol
Keyword(s):  
Plasma Membrane ◽  
Membrane Fusion ◽  
Freeze Fracture ◽  
Acid Synthesis ◽  
Extrusion Process ◽  
Membrane Lipid ◽  
Effect Of Temperature ◽  
Physiological Studies ◽  
And Function ◽  
Induced Changes

Previous studies on exocytosis in Paramecium using mutants affecting trichocyst extrusion permitted us to analyze the assembly and function of three intramembrane particle arrays ("ring" and "rosette" in the plasma membrane, "annulus" in the trichocyst membrane) involved in the interaction between these two membranes. Using a conditional mutation, nd9, which blocks rosette assembly and prevents exocytosis at the nonpermissive temperature, we have analyzed the effect of temperature on the secretory capacity of nd9 cells. By combining several techniques (physiological studies, microinjections, inhibition of fatty acid synthesis, and freeze-fracture analysis) we demonstrate (a) that the product of the mutated allele nd9 is not thermolabile but that its activity is dependent upon temperature-induced changes in the membrane lipid composition and (b) that the product of the nd9 locus is a diffusible cytoplasmic component whose interaction with both plasma membrane and trichocyst membrane is required for rosette assembly and exocytosis. The data provide physiological evidence for the existence of a molecular complex(es) linking the two membranes and involved in the control of membrane fusion; we discuss the possible nature and function of these links.

scholarly journals Role of N-glycosylation in trafficking of apical membrane proteins in epithelia

2009 ◽  
Vol 296 (3) ◽  
pp. F459-F469 ◽  
Author(s):  
Olga Vagin ◽  
Jeffrey A. Kraut ◽  
George Sachs
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Transporters ◽  
Membrane Domains ◽  
Sorting Signals ◽  
Galectin 3 ◽  
Vectorial Functions ◽  
Apical Sorting ◽  
Golgi Network

Polarized distribution of plasma membrane transporters and receptors in epithelia is essential for vectorial functions of epithelia. This polarity is maintained by sorting of membrane proteins into apical or basolateral transport containers in the trans-Golgi network and/or endosomes followed by their delivery to the appropriate plasma membrane domains. Sorting depends on the recognition of sorting signals in proteins by specific sorting machinery. In the present review, we summarize experimental evidence for and against the hypothesis that N-glycans attached to the membrane proteins can act as apical sorting signals. Furthermore, we discuss the roles of N-glycans in the apical sorting event per se and their contribution to folding and quality control of glycoproteins in the endoplasmic reticulum or retention of glycoproteins in the plasma membrane. Finally, we review existing hypotheses on the mechanism of apical sorting and discuss the potential roles of the lectins, VIP36 and galectin-3, as putative apical sorting receptors.

scholarly journals Thrombocytopoiesis--analysis by membrane tracer and freeze-fracture studies on fresh human and cultured mouse megakaryocytes.

1984 ◽  
Vol 99 (2) ◽  
pp. 390-402 ◽  
Author(s):  
D Zucker-Franklin ◽  
S Petursson
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Precursor Cell ◽  
Membrane Domains ◽  
Thin Sections ◽  
Energy Dependent ◽  
First Time ◽  
Later Phase ◽  
Peripheral Cytoplasm

The origin of platelets (Pt) from megakaryocytes (MK) is beyond question, but the mechanism whereby Pts are released from the precursor cell is still debated. A widely-held theory claims that the MK plasma membrane invaginates to form demarcation membranes (DMS), which delineate Pt territories. Accordingly, Pts would be derived mostly from the periphery of the MK, and the MK and Pt plasma membranes would have to be virtually identical. Since, on morphologic grounds, this theory is untenable, several aspects of thrombocytopoiesis were reexamined with the help of membrane tracer and freeze-fracture analyses of freshly-collected human and cultured mouse MK. To our surprise, freeze-cleavage of the MK plasma membrane revealed that the vast majority of intramembranous particles (IMP) remained associated with the protoplasmic leaflet (P face), whereas the partition coefficient of IMPs of the platelet membrane was the reverse. This is the first time that any difference between MK and Pt membranes has been determined. Replicas of freeze-fractured MK that were in the process of thrombocytopoiesis revealed an additional novel phenomenon, i.e., numerous areas of membrane discontinuity that appeared to be related to Pt discharge. When such areas were small, the IMP were lined up along the margin of the crevice. At a later phase, a labyrinth of fenestrations was observed. Thin sections of MK at various stages of differentiation showed that Pt territories were fully demarcated before connections of the DMS with the surface could be found. Therefore, the Pt envelope is probably not derived from invaginations of the MK plasma membrane. When living, MK were incubated with cationic ferritin or peroxidase at 37 degrees C, the tracers entered into the DMS but did not delineate all membranes with which the DMS was in continuity, suggesting the existence of distinctive membrane domains. Interiorization of tracer was not energy-dependent, but arrested at low temperatures. At 4 degrees C the DMS remained empty, unless there was evidence that Pts had been released. In such instances, the tracers outlined infoldings of peripheral cytoplasm that was devoid of organelles. Thus, the majority of Pts seem to originate from the interior of the MK, and the surface membranes of the two cells differ in origin and structure. The observations do not only throw new light on the process of thrombocytopoiesis, but also strengthen the possibility that MKs and Pts may be subject to different stimuli.

Expression and localization of hepatocyte domain-specific plasma membrane proteins in hepatoma × fibroblast hybrids and in hepatoma dedifferentiated variants

1998 ◽  
Vol 111 (22) ◽  
pp. 3437-3450
Author(s):  
V. Bender ◽  
S. Buschlen ◽  
D. Cassio
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Expression Patterns ◽  
Epithelial Polarity ◽  
Membrane Domains ◽  
Plasma Membrane Proteins ◽  
Dipeptidylpeptidase Iv ◽  
Domain Specific ◽  
Cell Clones ◽  
Discrete Domains

We have studied two aspects of the plasma membrane of hepatocytes, highly differentiated epithelial cells that exhibit a particular and complex polarity. Using a genetic approach, we have distinguished between the expression/regulation of proteins specific for all three hepatocyte membrane domains and their organization into discrete domains. For this analysis we used a panel of previously isolated cell clones, derived from the differentiated rat hepatoma line H4IIEC3, and that present different expression patterns for liver-specific genes. This panel was composed of (1) differentiated clones, (2) chromosomally reduced hepatoma-fibroblast hybrids characterized by a pleiotropic extinction/reexpression of liver-specific genes and (3) dedifferentiated variant and revertant clones. The expression of 16 hepatocyte membrane polarity markers was studied by western blotting and immunolocalization. Even though cells of differentiated clones express all of these polarity markers, they are not polarized, and are therefore suitable for studying the regulation of plasma membrane protein expression, and for identifying gene products implicated in the establishment of membrane polarity. In hepatoma-fibroblast hybrids the expression of four markers, three apical (dipeptidylpeptidase IV, alkaline phosphodiesterase B10 and polymeric IgA receptor) and one lateral (E-cadherin), is down-regulated in extinguished clones and restored in reexpressing subclones, as previously reported for liver-specific functions. The dipeptidylpeptidase IV mRNA was undetectable or strongly reduced in extinguished hybrids, but expressed at a robust level in some of the reexpressing clones. Concerning the dedifferentiated variants, each has its own pattern of membrane marker expression (loss of expression of three to six markers), that differs from that of extinguished hybrids. Revertant cells express all of the membrane markers examined. Among all of these hepatoma derivatives, only cells of reexpressing hybrids are polarized, and form bile canaliculi-like structures, with spherical and even, for one clone, long tubular and branched forms. All apical markers examined are confined in these canalicular structures, whereas the other markers are excluded from them, and present on the rest of the membrane (basolateral markers) or at the cell-cell contacts (lateral markers). Cells of reexpressing hybrids also express simple epithelial polarity. Thus the expression of only a few hepatocyte-domain-specific plasma membrane proteins is subject to down-regulation, as is the case for liver-specific genes so far studied, and the expression of polarity markers and the formation of poles are dissociable events.

Bimodal redistribution of surface transmembrane glycoproteins during Ca2+-dependent secretion (acrosome reaction) in boar spermatozoa

1989 ◽  
Vol 93 (3) ◽  
pp. 467-479
Author(s):  
A.P. Aguas ◽  
P.P. da Silva
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Freeze Fracture ◽  
Secretory Process ◽  
Membrane Domains ◽  
Cytoplasmic Vesicle ◽  
Acrosomal Membrane ◽  
Freeze Fracture Electron Microscopy ◽  
Boar Spermatozoa

We used the acrosome reaction of boar sperm cells to study the dynamics of surface transmembrane glycoproteins (TMG) during a secretory process. The acrosome reaction is the Ca2+-dependent fusion of a large cytoplasmic vesicle (the acrosome) with the overlying segment of the plasma membrane (acrosomal cap) that leads to the release of the acrosomal enzymes. After triggering the acrosome reaction in vitro (2 mM-CaCl2 in the presence of 10 microM-A23187), we used freeze-fracture electron microscopy to follow the topographical rearrangement of a population of acrosomal-cap large intramembrane particles that correspond to transmembrane proteins that bind wheat germ agglutinin. We found that these TMG move in the direction of either one of two opposite poles, proximal and distal, of the acrosomal cap. This bimodal movement of the TMG reorganizes the acrosomal cap into three extensive domains. The first two, on the apical rim and on the equator, are membrane domains to which the TMG are directed and where they accumulate. The third, a large in-between area of protein clearing, corresponds to the region from which TMG were preferentially located before displacement induced by the Ca2+ effect. The topography of these new membrane domains of the acrosomal cap becomes coincident with that of the structural domains of the subjacent acrosomal membrane. Mirroring of the acrosomal membrane by the plasma membrane is followed by fusion between the two membranes, formation of an exquisite labyrinth of hybrid-membrane tubules, followed by fission and release of the acrosomal contents through intertubular fenestrae.

scholarly journals The Human Plasma Membrane Peripherome: Visualization and Analysis of Interactions

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Katerina C. Nastou ◽  
Georgios N. Tsaousis ◽  
Kimon E. Kremizas ◽  
Zoi I. Litou ◽  
Stavros J. Hamodrakas
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Human Plasma ◽  
Noncovalent Interactions ◽  
Interaction Network ◽  
Subcellular Location ◽  
Membrane Function ◽  
Peripheral Membrane Proteins ◽  
Peripheral Proteins ◽  
Approved Drugs

A major part of membrane function is conducted by proteins, both integral and peripheral. Peripheral membrane proteins temporarily adhere to biological membranes, either to the lipid bilayer or to integral membrane proteins with noncovalent interactions. The aim of this study was to construct and analyze the interactions of the human plasma membrane peripheral proteins (peripherome hereinafter). For this purpose, we collected a dataset of peripheral proteins of the human plasma membrane. We also collected a dataset of experimentally verified interactions for these proteins. The interaction network created from this dataset has been visualized using Cytoscape. We grouped the proteins based on their subcellular location and clustered them using the MCL algorithm in order to detect functional modules. Moreover, functional and graph theory based analyses have been performed to assess biological features of the network. Interaction data with drug molecules show that ~10% of peripheral membrane proteins are targets for approved drugs, suggesting their potential implications in disease. In conclusion, we reveal novel features and properties regarding the protein-protein interaction network created by peripheral proteins of the human plasma membrane.

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