Electron microscopic detection of calcium binding to the duodenal absorptive cell plasma membranes

1977 ◽  
Vol 150 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Sohan S. Jande
Keyword(s):  
Calcium Binding ◽  
Plasma Membranes ◽  
Absorptive Cell ◽  
Electron Microscopic ◽  
Microscopic Detection ◽  
Cell Plasma

scholarly journals SYNAPTIC STRUCTURES IN THE LATERAL LINE CANAL ORGAN OF THE TELEOST FISH LOTA VULGARIS

1962 ◽  
Vol 13 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Åke Flock ◽  
Jan Wersäll
Keyword(s):  
Hair Cell ◽  
Lateral Line ◽  
Teleost Fish ◽  
Plasma Membranes ◽  
Sensory Epithelium ◽  
Electron Microscopic ◽  
Lateral Line Canal ◽  
Cell Plasma ◽  
Microscopic Studies ◽  
Synaptic Structures

This paper is a preliminary report on some of the results of electron microscopic studies on the lateral line canal organ of the teleost fish Lota vulgaris. It deals with the ultrastructure of the synaptic area on the hair cells of the sensory epithelium and describes the nerve endings as well as a complicated system of foldings of the hair cell plasma membranes enclosing portions of the hair cell cytoplasm in the synaptic area. These findings are discussed in the light of present knowledge of the ultrastructure of other receptoneuronal synapses.

A molecular basis for synexin-driven, calcium-dependent membrane fusion

1988 ◽  
Vol 139 (1) ◽  
pp. 267-286
Author(s):  
H. B. Pollard ◽  
A. L. Burns ◽  
E. Rojas
Keyword(s):  
Membrane Fusion ◽  
Calcium Binding ◽  
Plasma Membranes ◽  
Cell Types ◽  
Complete Analysis ◽  
Calcium Dependent ◽  
Cell Plasma ◽  
Probable Role ◽  
Highly Hydrophobic ◽  
Chromaffin Granule Ghosts

Membranes of secretory vesicles fuse with each other and with plasma membranes during exocytosis in many different cell types. The probable role of calcium in the process is now widely accepted, and it is possible that at least one cytosolic mediator of calcium action is synexin. Synexin is a 47,000 Mr calcium-binding protein, initially discovered in the bovine adrenal medulla, which binds to granule membranes and to inner aspects of chromaffin cell plasma membranes. Synexin causes chromaffin granules to aggregate, and such aggregates can be caused to fuse in the additional presence of arachidonic acid. Synexin also mediates the direct fusion of liposomes and chromaffin granule ghosts. To understand better the mechanisms of membrane fusion promoted by synexin we have attempted to define the primary sequence of the protein. Our initial efforts were directed towards purification of bovine synexin in sufficient amounts to allow us to sequence tryptic peptides. However, as the project progressed we also directed our attention to human synexin, preparing peptides from this protein as well. From analysis of bovine peptides we learned that the synexin molecule might be closely related to a class of proteins including lipocortin I, calpactin (p36), endonexin II, protein II and calelectrin 67K. Complete analysis of a human synexin cDNA clone revealed strong homology with bovine synexin. The analysis also showed that synexin contained a unique, long, highly hydrophobic N-terminal leader sequence followed by a characteristic four-fold repeat homologous with those found in other members of the synexin gene family. The highly hydrophobic character of synexin seems consistent with information previously obtained that synexin is able to insert directly into the interior of bilayers prepared not only from purified phosphatidylserine but also from biological membranes. The evidence for such insertions is a dramatic increase in the capacitance of the membrane, formed at the tip of a patch pipette, when calcium-activated synexin is applied to the bilayer. Additional evidence is the fact that synexin also forms calcium-selective channels when the protein is applied to the cytosolic aspect of the plasmalemma when that side is also exposed to calcium at sub-millimolar concentrations. Thus, the synexin molecule not only enters the membrane, but also spans it. From these and other data we have developed the concept that the fusion process may involve synexin forming a ‘hydrophobic bridge’ between two fusing membranes. Lipid movement across this bridge may then be the material basis for final fusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Calcium binding by parathyroid cell plasma membranes

Cell Calcium ◽  
1987 ◽  
Vol 8 (2) ◽  
pp. 171-183 ◽  
Author(s):  
Federica Wolf ◽  
Antonio Scarpa
Keyword(s):  
Calcium Binding ◽  
Plasma Membranes ◽  
Parathyroid Cell ◽  
Cell Plasma

scholarly journals Preliminary characterization of calcium binding in islet-cell plasma membranes

Diabetologia ◽  
1980 ◽  
Vol 19 (5) ◽  
pp. 439-444 ◽  
Author(s):  
S. P. Naber ◽  
J. M. McDonald ◽  
L. Jarett ◽  
M. L. McDaniel ◽  
C. W. Ludvigsen ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Islet Cell ◽  
Plasma Membranes ◽  
Preliminary Characterization ◽  
Cell Plasma

p-Chloromercurobenzene sulfonate inhibition of active Cl- transport in plasma membrane vesicles from Aplysia gut

1990 ◽  
Vol 259 (6) ◽  
pp. R1111-R1116
Author(s):  
G. A. Gerencser
Keyword(s):  
Plasma Membrane ◽  
Transport Process ◽  
Transport Mechanism ◽  
Plasma Membranes ◽  
Membrane Vesicles ◽  
Sucrose Density Gradient ◽  
Absorptive Cell ◽  
Plasma Membrane Vesicles ◽  
Cl Transport ◽  
Cell Plasma

Both a Cl(+)-stimulated adenosinetriphosphatase (ATPase) activity and an ATP-dependent Cl- transport process were found in Aplysia foregut absorptive cell plasma membranes. In an attempt to further characterize this transport process, plasma membrane vesicles from Aplysia foregut absorptive cells were prepared utilizing differential centrifugation and sucrose density-gradient techniques. Sulfhydryl ligand participation in ATP-dependent Cl- transport was confirmed in three ways. First, 1,4-dithiothreitol partially restored a p-chloromercurobenzene sulfonate (PCMBS)-inhibited ATP-dependent Cl- transport. Second, 1,4-dithiothreitol restored intravesicular negativity inhibited by PCMBS. Third, 1,4-dithiothreitol had no effect on either ATP-dependent Cl- transport or ATP-dependent intravesicular negativity inhibited by N-ethylmaleimide. These results are consistent with the hypothesis that surface sulfhydryl groups participate in the functioning of the active electrogenic Cl- transport mechanism in Aplysia gut.

Electron Microscopic Detection and Characterization of Nonhuman Primate Enteric Viruses

1982 ◽  
Vol 40 ◽  
pp. 306-307
Author(s):  
G. C. Smith ◽  
R. L. Heberling ◽  
S. S. Kalter
Keyword(s):  
Electron Microscopy ◽  
Animal Model ◽  
Nonhuman Primate ◽  
Clinical Condition ◽  
Intestinal Tract ◽  
Enteric Viruses ◽  
Electron Microscopic ◽  
Microscopic Detection

A number of viral agents are recognized as and suspected of causing the clinical condition “gastroenteritis.” In our attempts to establish an animal model for studies of this entity, we have been examining the nonhuman primate to ascertain what viruses may be found in the intestinal tract of “normal” animals as well as animals with diarrhea. Several virus types including coronavirus, adenovirus, herpesvirus, and picornavirus (Table I) were detected in our colony; however, rotavirus, astrovirus, and calicivirus have not yet been observed. Fecal specimens were prepared for electron microscopy by procedures reported previously.

scholarly journals Characterization of calcium binding to adipocyte plasma membranes.

1976 ◽  
Vol 251 (17) ◽  
pp. 5345-5351
Author(s):  
J M McDonald ◽  
D E Bruns ◽  
L Jarett
Keyword(s):  
Calcium Binding ◽  
Plasma Membranes ◽  
Adipocyte Plasma Membranes

scholarly journals Insulin-induced rapid decrease of a major protein in fat cell plasma membranes.

1984 ◽  
Vol 259 (19) ◽  
pp. 12112-12116
Author(s):  
E J Schoenle ◽  
L D Adams ◽  
D W Sammons
Keyword(s):  
Plasma Membranes ◽  
Rapid Decrease ◽  
Major Protein ◽  
Fat Cell ◽  
Cell Plasma

scholarly journals Charged anaesthetics alter LM-fibroblast plasma-membrane enzymes by selective fluidization of inner or outer membrane leaflets

1986 ◽  
Vol 239 (2) ◽  
pp. 301-310 ◽  
Author(s):  
W D Sweet ◽  
F Schroeder
Keyword(s):  
Plasma Membrane ◽  
Active Site ◽  
Plasma Membranes ◽  
Local Anaesthetics ◽  
Cationic Drugs ◽  
Cell Plasma ◽  
Composition And Structure ◽  
Highly Sensitive ◽  
Functional Consequences ◽  
Anionic Drugs

The functional consequences of the differences in lipid composition and structure between the two leaflets of the plasma membrane were investigated. Fluorescence of 1,6-diphenylhexa-1,3,5-triene(DPH), quenching, and differential polarized phase fluorimetry demonstrated selective fluidization by local anaesthetics of individual leaflets in isolated LM-cell plasma membranes. As measured by decreased limiting anisotropy of DPH fluorescence, cationic (prilocaine) and anionic (phenobarbital and pentobarbital) amphipaths preferentially fluidized the cytofacial and exofacial leaflets respectively. Unlike prilocaine, procaine, also a cation, fluidized both leaflets of these membranes equally. Pentobarbital stimulated 5′-nucleotidase between 0.1 and 5 mM and inhibited at higher concentrations, whereas phenobarbital only inhibited, at higher concentrations. Cationic drugs were ineffective. Two maxima of (Na+ + K+)-ATPase activation were obtained with both anionic drugs. Only one activation maximum was obtained with both cationic drugs. The maximum in activity below 1 mM for all four drugs clustered about a single limiting anisotropy value in the cytofacial leaflet, whereas there was no correlation between activity and limiting anisotropy in the exofacial leaflets. Therefore, although phenobarbital and pentobarbital below 1 mM fluidized the exofacial leaflet more than the cytofacial leaflet, the smaller fluidization in the cytofacial leaflet was functionally significant for (Na+ + K+)-ATPase. Mg2+-ATPase was stimulated at 1 mM-phenobarbital, unaffected by pentobarbital and slightly stimulated by both cationic drugs at concentrations fluidizing both leaflets. Thus the activity of (Na+ + K+)-ATPase was highly sensitive to selective fluidization of the leaflet containing its active site, whereas the other enzymes examined were little affected by fluidization of either leaflet.

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