scholarly journals Self-digestion of human erythrocyte membranes. Role of adenosine triphosphate and glutathione

1977 ◽  
Vol 164 (2) ◽  
pp. 469-472 ◽  
Author(s):  
A Brovelli ◽  
M Suhail ◽  
G Pallavicini ◽  
F Sinigaglia ◽  
C Balduini
Keyword(s):  
Chemical Composition ◽  
Adenosine Triphosphate ◽  
Human Erythrocyte ◽  
Incubation Medium ◽  
Reduced Glutathione ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Digestion Process ◽  
Human Erythrocyte Membranes

Intact human erythrocytes incubated at 37 degrees C, pH7.4, release a sialoglycopeptide similar in its chemical composition, immunological and aggregation properties to the glycopeptide released by isolated ‘ghost’ membranes. The presence of ATP or reduced glutathione at physiological concentrations in the incubation medium of ‘ghost’ membranes inhibits this self-digestion process.

Evidence against the Involvement of Mutarotase in the D-Glucose Uptake Activity of Isolated Human Erythrocyte Membranes

1972 ◽  
Vol 50 (9) ◽  
pp. 1028-1030 ◽  
Author(s):  
Arthur Kahlenberg ◽  
Gary Miller
Keyword(s):  
Glucose Uptake ◽  
Membrane Transport ◽  
Glucose Transport ◽  
Human Erythrocyte ◽  
Transport Process ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membranes ◽  
Uptake Activity ◽  
Glucose Carrier

Mutarotase, the enzyme catalyzing the interconversion of the anomeric forms of D-glucose, has recently been suggested to be the membrane glucose carrier in human erythrocytes. However, hemoglobin-free human erythrocyte membranes possessing D-glucose uptake activity were found to be free of mutarotase activity. Mutarotase activity was detected in the membrane-free hemolysates of the cells. It is therefore concluded that the D-glucose uptake activity of isolated erythrocyte membranes is not due to the binding of the sugar to mutarotase, and that this enzyme is not involved in glucose transport in a manner compatible with most presently held concepts of the membrane transport process.

scholarly journals Labelling of the intramembranous region of the major sialoglycoprotein of human erythrocytes with a photosensitive hydrophobic probe

1979 ◽  
Vol 179 (2) ◽  
pp. 265-272 ◽  
Author(s):  
E Wells ◽  
J B Findlay
Keyword(s):  
Membrane Proteins ◽  
Human Erythrocyte ◽  
Human Erythrocytes ◽  
Labelling Pattern ◽  
Erythrocyte Membranes ◽  
Transmembrane Region ◽  
Human Erythrocyte Membranes ◽  
Hydrophobic Probe

Human erythrocyte membranes were incubated with the photosensitive hydrophobic reagent 1-azido-r-iodo[3H]benzene and the mixture was irradiated. The major sialoglycoprotein was then isolated and the labelled polypeptide subjected to proteolytic dissection. Characterization of the purified tryptic and chymotryptic peptides show that the probe is covalently attached only to the transmembrane region of the protein. This labelling pattern is discussed in relation to the use of such reagents for the identification of segments of membrane proteins exposed to the hydrophobic millieu of the membrane.

scholarly journals Identification of a sialoglycopeptide released by self-digestion from human erythrocyte membranes

1976 ◽  
Vol 158 (2) ◽  
pp. 497-500 ◽  
Author(s):  
A Brovelli ◽  
G Pallavicini ◽  
F Sinigaglia ◽  
C L Balduini ◽  
C Balduini
Keyword(s):  
Amino Acids ◽  
Chemical Composition ◽  
Human Erythrocyte ◽  
Molecular Size ◽  
Erythrocyte Membranes ◽  
Erythrocyte Ghosts ◽  
Human Erythrocyte Membranes

Membranes from human O Rhesus-positive erythrocyte ‘ghosts’ were tested in vitro for their ability to digest their own glycoproteins. ‘Ghost’ membranes incubated in Tris/HCl buffer, pH 7.4, release a sialoglycopeptide, which contains glucosamine, galactosamine, galactose and mainly polar amino acids. Chemical composition, molecular size and aggregation properties suggest that this glycopeptide may be a fragment of glycophorin.

scholarly journals On the mechanism of ATP-induced shape changes in human erythrocyte membranes. I. The role of the spectrin complex.

1977 ◽  
Vol 73 (3) ◽  
pp. 638-646 ◽  
Author(s):  
M P Sheetz ◽  
S J Singer
Keyword(s):  
Human Erythrocyte ◽  
Network Formation ◽  
Structural Effect ◽  
Erythrocyte Membranes ◽  
Cross Linking ◽  
Intact Cells ◽  
Cytoplasmic Face ◽  
Human Erythrocyte Membranes ◽  
Shape Changes

Human erythrocyte ghosts have been shown, by scanning electron microscopy, to undergo ATP-dependent shape changes. Under appropriate conditions the ghosts prepared from normal disk-shaped intact cells adopt a highly crenated shape, which in the presence of Mg-ATP at 37 degrees C is slowly converted to the disk shape and eventually to the cup shape. These changes are not observed with other nucleotides or with 5'-adenylyl imidodiphosphate. Anti-spectrin antibodies, incorporated along with the Mg-ATP into the ghosts in amounts less than equivalent to the spectrin, markedly accelerate the shape changes observed with the Mg-ATP alone. The Fab fragments of these antibodies, however, have no effect. The conclusion is that the structural effect produced by the ATP is promoted by the cross-linking of spectrin by its antibodies, and may therefore itself be some kind of polymerization or network formation involving the spectrin complex on the cytoplasmic face of the membrane. The factors that contribute to the shape of the ghost and of the intact erythrocyte are discussed in the light of these findings.

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