Freeze-fracture electron microscopic observations on the effects of sulphydryl group reagents on human erythrocyte membranes

1987 ◽  
Vol 11 (9) ◽  
pp. 679-687 ◽  
Author(s):  
G BENGA ◽  
A BRAIN ◽  
V POP ◽  
A HODARNAU ◽  
J WRIGGLESWORTH
Keyword(s):  
Human Erythrocyte ◽  
Freeze Fracture ◽  
Erythrocyte Membranes ◽  
Electron Microscopic ◽  
Sulphydryl Group ◽  
Human Erythrocyte Membranes ◽  
Fracture Electron

Freeze-fracture Electron Microscopic observations on the effects of sulphydryl group reagents on human erythrocyte membranes

1990 ◽  
Vol 48 (3) ◽  
pp. 524-525 ◽  
Author(s):  
Gheorghe Benga ◽  
Anthony Brain ◽  
Victor I. Pop ◽  
John Wrigglesworth
Keyword(s):  
Human Erythrocyte ◽  
Freeze Fracture ◽  
Band 3 ◽  
Erythrocyte Membranes ◽  
Electron Microscopic ◽  
Experimental Conditions ◽  
Water Permeation ◽  
Human Erythrocyte Membranes ◽  
Erythrocyte Membrane Proteins

The intra-membrane particles (IMPs) observed on the fracture face of frozen erythrocyte membranes are thought to correspond primarily to “band 3” tetramers or dimers. Some recent studies correlating the inhibition of water diffusion in erythrocytes by p-chloromercuribenzene sulfonate (PCMBS) with the binding of 203Hg to erythrocyte membrane proteins has enabled band 3 and the polypeptides in band 4.5 to be identified as the proteins associated with the channels for water permeation in human erythrocytes. A further characterization of the effects of the incubation of human erythrocyte membranes with PCMBS and N-ethylmaleimide (NEM) has been performed as previously described. Experimental conditions have been previously described.A comparison was made of the appearance of freeze-etched membranes of control erythrocytes and erythrocytes with the sulphydryl reagents. It was found that on many of the control and NEM-treated cells, small (50-100 nm) elevated patches could be seen (Fig. 1, 2 and 3). These are present on both fracture and etch faces and are devoid of any intramembrane particles. The patch elevations were never observed in the membranes of PCMBS-treated cells (Fig. 4).

scholarly journals Freeze-fracture cytochemistry: partition of glycophorin in freeze-fractured human erythrocyte membranes.

1982 ◽  
Vol 93 (2) ◽  
pp. 463-469 ◽  
Author(s):  
P P da Silva ◽  
M R Torrisi
Keyword(s):  
Human Erythrocyte ◽  
Binding Sites ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Transmembrane Protein ◽  
Freeze Fracture ◽  
Membrane Skeleton ◽  
Erythrocyte Membranes ◽  
Con A ◽  
Human Erythrocyte Membranes

Thin-section and critical-point-dried fracture-labeled preparations are used to determine the distribution and partition of glycophorin-associated wheat germ agglutinin (WGA) binding sites over protoplasmic and exoplasmic faces of freeze-fractured human erythrocyte membranes. Most wheat germ agglutinin binding sites are found over exoplasmic faces. Label is sparse over the protoplasmic faces. These results contrast with previous observations of the partition of band 3 component where biochemical analysis and fracture-label of concanavalin A (Con A) binding sites show preferential partition of this transmembrane protein with the protoplasmic face. Presence of characteristic proportions of WGA and Con A binding sites over each fracture face is interpreted to indicate the operation of a stochastic process during freeze-fracture. This process appears modulated by the relative expression of each transmembrane protein at either surface as well as by their association to components of the erythrocyte membrane skeleton.

Effect of Integral Proteins on Frozen Membrane Fracture

1980 ◽  
Vol 38 ◽  
pp. 756-759 ◽  
Author(s):  
S. Kirchanski ◽  
D. Branton
Keyword(s):  
Lipid Bilayers ◽  
Freeze Fracture ◽  
Covalent Bond ◽  
Erythrocyte Membranes ◽  
Glycophorin A ◽  
Experimental Protocol ◽  
Transmembrane Glycoprotein ◽  
Bond Breakage ◽  
Human Erythrocyte Membranes ◽  
Integral Proteins

We have investigated the effect of integral membrane proteins upon the fracturing of frozen lipid bilayers. This investigation has been part of an effort to develop freeze fracture labeling techniques and to assess the possible breakage of covalent protein bonds during the freeze fracture process. We have developed an experimental protocol utilizing lectin affinity columns which should detect small amounts of covalent bond breakage during the fracture of liposomes containing purified (1) glycophorin (a transmembrane glycoprotein of human erythrocyte membranes). To fracture liposomes in bulk, frozen liposomes are ground repeatedly under liquid nitrogen. Failure to detect any significant covalent bond breakage (contrary to (2)) led us to question the effectiveness of our grinding procedure in fracturing and splitting lipid bilayers.

scholarly journals Interaction of platelet plasma membranes with thrombin-activated platelets

Blood ◽  
1981 ◽  
Vol 57 (2) ◽  
pp. 305-312 ◽  
Author(s):  
HR Prasanna ◽  
HH Edwards ◽  
DR Phillips
Keyword(s):  
Human Erythrocyte ◽  
Plasma Membranes ◽  
Membrane Binding ◽  
Human Platelets ◽  
Platelet Membrane ◽  
Erythrocyte Membranes ◽  
Functional Sites ◽  
Activated Platelets ◽  
Platelet Membranes ◽  
Human Erythrocyte Membranes

Abstract This study described the binding of platelet plasma membranes to either control or thrombin-activated platelets. Glycoproteins in plasma membranes isolated from human platelets were labeled by oxidation with periodate followed by reduction with [3H]NaBH4. Labeled membranes were incubated with either control or thrombin-activated platelets. The amount of membranes bound was measured by separating platelets with bound membranes from solution by rapid centrifugation through 27% sucrose and determining the amount of radioactivity associated with platelets. Five- to sevenfold more membranes bound to thrombin- activated platelets than to control platelets. This enhanced binding of labeled membranes was completely inhibited by an excess of unlabeled platelet membranes. Human erythrocyte membranes had little affinity for either washed or thrombin-activated platelets and therefore did not compete for platelet-membrane binding. Binding of platelet membranes to thrombin-treated platelets was inhibited by prior incubation of the platelets with PGI2 suggesting that the enhanced binding of membranes was to activated platelets. This study demonstrates that the purified platelet membranes have functional sites that can mediate membrane binding to platelets and that quantitation of membrane binding appears to reflect the increased aggregation capability of activated platelets.

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