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At least 19 recordsLinked to original sources
PubMed1978

The interaction of short-chain aralkyl alcohols and amines with the erythrocyte membrane.

Erythrocytes in isotonic saline are hemolyzed by benzyl alcohol and by 2-phenylethanol, but not by the corresponding amines nor by the ring-or side-chain-hydroxylated analogs. All these compounds could however interact with the erythrocyte membrane since: a) they facilitated the hemolytic effect of benzyl alcohol and/or of phenylelytic effect of benzyl alcohol and/or of phenylethanol; b) they exerted a protective effect against controlled hypotonic hemolysis.

Alcohols↗
PubMed1978

Alterations of membrane phosphorylation in erythrocyte membranes from patients with Duchenne muscular dystrophy.

The phosphorylation of spectrin, band 3 protein, and the phospholipids of erythrocyte membranes (ghosts) was examined in 10 patients with Duchenne muscular dystrophy (DMD) and in healthy age- and sex-matched controls. The rates of phosphorylation of spectrin and band 3 protein were significantly higher in ghosts prepared from patient blood than from control blood at both 30 degrees C and 37 degrees C. However, the mean increases in the rate of phosphorylation of both spectrin and band 3 protein in response to a temperature change from 30 degrees C to 37 degrees C were identical in ghosts from patient and controls. Phosphorylation of phospholipid and its temperature response did not differ between patients and controls. These results complement previous observations of differences in erythrocytes from patients with DMD. The similarity of the changes in phosphorylation of both spectrin and band 3 protein indicates a common cause, possibly their lipid environment.

Adult↗
PubMed1979

Myotonic muscular dystrophy: abnormal temperature response of membrane phosphorylation in erythrocyte membranes.

The activities of the membrane-bound protein kinases of the human erythrocytes membrane that phosphorylate spectrin, band-3 protein, and phospholipids were compared in patients with myotonic muscular dystrophy and normal age- and sex-matched controls. These activities tended to be lower in the patients, but the differences were not statistically significant. In contrast, the temperature responses (the increase in activity in response to an increase in temperature from 30 degrees C to 37 degrees C) of the spectrin and band-3 protein kinase activities were significantly lower in the patients. Although they do not eliminate an alteration of one of the substrates, these results are consistent with the proposal that differences in erythrocytes from myotonic muscular dystrophy (MyD) patients are due to a membrane lipid change. Cholesterol is unlikely to be the altered lipid, as no difference in membrane cholesterol content was found.

Adenosine Triphosphate↗
PubMed1978

Electrical properties and glucose permeability of bilayer lipid membranes on incorporation of erythrocyte membrane extracts.

1. Extracts of the human erythrocyte membrane have been prepared by solubilization with Triton X-100 and analysed by electrophoresis and gel filtration techniques. 2. The extracts have been incorporated asymmetrically into lecithincholesterol-n-decane planar bilayers. 3. The electrical characteristics and glucose permeabilities of the bilayers have been measured. 4. The extracts increased the electrical conductance of the bilayers and also markedly enhanced the D-glucose permeability but not the L-glucose permeability. 5. The enhanced D-glucose permeability was inhibited by monosaccharide transport inhibitors. 6. The results support the claim that a monosachharide facititated diffusion system has been set-up in vitro which has many of the characteristics of the transport system in the human erythrocyte membrane. 7. The data indicates that the trans membrane polypeptides of band 3 of the electrophoretogram of the erythrocyte membrane proteins (notation of Fairbanks, G., Steck, T.L. and Wallach, D.F.H. (1971) Biochemistry 10, 2606-2616) are implicated in D-glucose transport, although the possibility that relatively minor component of the membrane could be responsible for glucose transport cannot be eliminated.

Cell Membrane Permeability↗
PubMed1975

Proteolytic activity associated with human erythrocyte membranes. Self-digestion of isolated human erythrocyte membranes.

At least two kinds of enzymes are active in the proteolytic self-digestion of erythrocyte membranes. The specific activities of these enzymes do not decrease with repeated washings of purified stroma. The effects of a variety of inhibitors on the membrane preparation's capacity to digest 125-I-labelled casein, covalently linked to latex beads, have been examined. Pepstatin-inhibitable enzyme, active at low pH, digests the membrane extensively to small polypeptide fragments. Spectrin, located at the internal part of the membrane, is readily degraded. Diisopropylfluorophosphate-inhibitable enzyme, active at pH 8-9, has only limited digestive capacity. Some of the membrane components, such as the small molecular weight glycoproteins, are resistant to digestion. The restricted capacity of digestion is due to the membrane molecular arrangement; increased disaggregation removes the restriction and increases the activity. Spectrin is not digested unless the membrane topography is disrupted by NP-40 neutral detergent. These observations suggest that the enzymes active at basic pH are located external to the cell. Intact cells do possess a limited capacity to degrade 125-I-labelled casein when their surfaces are brought into contact with substrate-coated beads.

Aprotinin↗
PubMedDate not supplied

[Proteins of erythrocytic membrane. II. Solubilization of proteins in the membrane of human erythrocytes by chlorpromazine (author's transl)].

At the concentration above 2 mM, chlorpromazine induces partial solubilization of human erythrocytic membrane proteins. High molecular weight components such as spectrin are not extracted. Glycoproteins are preferentially released: at least five glycoprotein components are separated by acrylamide gel electrophoresis after specific staining. Other non identified proteins of the ghost external surface are also solubilized. At high concentration total solubilization of ghosts is obtained. Material extracted by chlorpromazine may be used for further protein purification.

Blood Proteins↗
PubMed1979

Active Ca2+ transport by vesicles reconstituted from Triton X-100-solubilized pigeon erythrocyte membrane.

Pigeon erythrocyte membrane was solubilized partially, but relatively unselectively by Triton X-100. Vesicles were reconstituted from mixtures of Triton-solubilized membrane and lipid (phosphatidylcholine plus phosphatidyl-ethanolamine plus cholesterol) by addition of bovine high-density lipoprotein. This efficiently removed the Triton X-100. Sodium dodecyl sulfate-polyacrylamide gel electropherograms of reconstituted vesicles showed band patterns resembling those of the original membrane. The reconstituted vesicles showed ATP-dependent active accumulation of 45Ca2+. ATP-dependent 45Ca2+ uptake by the reconstituted vesicles resembled the corresponding activity of the original membrane vesicles; in both preparations the Ca2+ uptake rate depended on the square of the Ca2+ concentration and had similar [Ca2+]1/2 values, 0.16 microM and 0.18 microM, respectively.

Adenosine Triphosphate↗
PubMed1978

[Reaction between anti-erythrocyte-membrane immune sera and erythrocytes of patients with homozygous beta-thalassemia. Observations made with immunofluorescence and immunoperoxidase methods].

The immunofluorescence and immunoperoxidase techniques have been applied to erythrocytes from the periferal blood of beta thalassemia patients, coated with rabbit anti human erythrocyte membrane antibodies. Enhanced staininh has been found in a number of mature and immature red blood cells, as well as the presence of plasma proteins sticking to the surface of the erythrocytes.

Animals↗
PubMed1976

Unique properties of the camel erythrocyte membrane, II. Organization of membrane proteins.

Camel erythrocyte membranes are distinguished by some unique properties of stability and composition. Notable is their abundance in proteins (protein:lipid ratio of 3:1). Membrane proteins of camel erythrocytes were compared with those of human eruthrocytes, which have been intensively investigated. Proteins were extracted with various aqueous media (EDTA, alkaline or high ionic strength) and with ionic and non-ionic detergents and were analyzed by gel electrophoresis. In membranes of camel erythrocytes, the peripheral proteins constitute, proportionally, a much smaller fraction of total proteins than in the human erythrocyte, while their distribution is identical per unit of surface area. The camel erythrocyte membrane is particularly rich in integral proteins and in intramembranous particles. The proteins in this membrane are more closely organized than in the human system, as revealed by crosslinking and freeze-etching studies. It is proposed that protein-protein interaction of integral proteins, presumably constituting an "integral skeleton", is a dominant structural feature stabilizing the camel erythrocyte membrane.

Animals↗
PubMed1977

Effect of hyperoxide radicals on bovine-erythrocyte membrane.

1. Bovine erythrocytes exposed to the action of an enzymic source of hyperoxide radicals (hypoxanthine + xanthine oxidase) exhibited hemolysis, which was prevented by the presence of hyperoxide dismutase. 2. Exposing bovine erythrocyte membranes to the source of hyperoxide radicals resulted in a decrease of (Mg2+ + Na+ + K+)ATPase activity which could be partially prevented by addition of hyperoxide dismutase. 3. The damage observed to erythrocyte membranes under the conditions applied is ascribed to toh formed in the Haber and Weiss reaction since a protection by OH scavengers was also observed.

Adenosine Triphosphatases↗
PubMed1979

The permeability of bilayer lipid membranes on the incorporation of erythrocyte membrane extracts and the identification of the monosaccharide transport proteins.

1. Extracts of the human erythrocyte membrane have been prepared by five different procedures involving Triton X-100 solubilization and gel chromatography. 2. The extracts have been analysed by gel electrophoresis and incorporated asymmetrically into phosphatidylcholine-cholesterol-n-decane planar bilayers. 3. Removal of excess Triton X-100 from membrane extracts or prolonged storage facilities the proteolysis of membrane extracts with the partial or complete breakdown of band 3 polypeptides (notation of Fairbanks, G., Steck, T.L. and Wallach, D.F.H. (1971) Biochemistry 10, 2606--2616) and the appearance of an enhanced zone 4.5 and low molecular weight material. 4. Incorporation of zone 4.5 polypeptides into bilayer lipid membranes increases their permeability to D-glucose at 27 and 5 degrees C. 5. It is suggested that the components of the monosaccharide system are present in band 3 polypeptides but that they can undergo proteolysis with some retention of transport activity.

Carrier Proteins↗
PubMed1978

Stimulation of calcium transport in inside-out vesicles of human erythrocyte membranes by a soluble cytoplasmic activator.

Transport of Ca2+ by inside-out vesicles requires both Mg2+ and ATP and can be linear over 16 min at 37 degrees C. This basal rate of transport may be doubled however by an activator found in membrane-free erythrocyte hemolysate. This activatior is probably the same protein (s) which has been shown to activate (Ca2+ + Mg2+)-ATPase in erythrocyte membrane fragments (Bond, G.H. and Clough, D.E. (1973) Biochim. Biophys. Acta 323, 592--599).

Biological Transport, Active↗
PubMed1978

Fatty acid and alcohol partitioning with intestinal brush border and erythrocyte membranes.

Relative partition coefficients of fatty acids and alcohols between aqueous buffers and biological membranes have been determined from the linear relationship between isotope content of sedimented membranes and aqueous concentration. This technique allows study of highly lipid soluble compounds such as long-chain saturated fatty acids. Rat intestinal brush border membranes and erythrocyte ghost membranes were studied by using homologous series of saturated fatty acids, mono-unsaturated fatty acids and 10, 12, and 14 carbon normal alcohols. The influence of chain length on partitioning was similar in the three series with an incremental free energy of -820 cal/mole per methylene group in brush borders for the saturated fatty acids. Incremental enthalpy and entropy were -1331 cal/mole and -1.64 cal/mole, degrees K respectively. Decrease in the partition coefficient due to the double bond (monounsaturated relative to saturated) had an incremental free energy of +1178 cal/mole, incremental enthalpy of -3453 cal/mole, and incremental entropy of -7.34 cal/mole, degrees K, while substitution of the hydroxyl for the ionized carboxyl group (pH 7.4) increased the partition coefficient by 72-fold. From these data it must be concluded that the lipid phase of the membrane bilayer is extremely hydrophobic, similar to heptane or polyethylene in polarity.

Animals↗
PubMedDate not supplied

Variability of conductivity changes in black phosphatidylserine membranes induced by proteins from erythrocyte membranes.

The electrical conductivity of black phosphatidylserine membranes, in solutions of 100 mM NaCl, 10 mM sodium phosphate (pH 7.1), is strongly increased by the intrinsic proteins ("strongly bound" protein fraction) from human erythrocyte membranes. The magnitude of the conductivity increase is highly dependent on the maximum pH-value pH used during the preparation of the protein (8.0 less than or equal to pH less than or equal 11.8). For each pH, membrane conductivity lambdaf and protein concentration c are linked by the equation lambdaf=k-cs, k and s being functions only of pH. The value of s varies between 1.0 (pH 8) and 4.0 (pH 10). It is assumed that the protein-induced conducting sites, at least for protein pretreatment at pH less than or equal to 10, are assembled from four protein subunits. The incorporation of the subunits into the lipid bilayer is supposed to occur either as the final tetramer (pH 8) or as monomers (pH 10) and possibly dimers (pH around 9).

Animals↗
PubMed1978

Electron spin resonance studies on interaction of complement proteins with erythrocyte membranes.

Sheep erythrocytes have been spin labeled with 5-, 12-, and 16-nitroxystearic acid in order to investigate complement-induced changes in the physical state of the lipid bilayer. Formation of osmotic lesions in the membrane causes an increase in the fluidity of the membrane which overcomes the decrease in membrane fluidity caused by the interaction of the complement proteins. A decrease in membrane fluidity is observed only when complement-lysed membranes are resealed or when complement proteins react with isosmolar ghosts that do not undergo osmotic lysis. The decrease in bulk fluidity of the membrane is first observed when C8 binds to the membranes bearing C5b67 and is enhanced upon the subsequent binding of C9. The decrease in membrane fluidity shown by the electron spin resonance spectra of spin-labeled fatty acids suggests that certain of the complement proteins penetrate the membrane and interact with hydrophobic regions of the lipid bilayer.

Animals↗
PubMed1979

Binding of lipoteichoic acid of group A streptococci to isolated human erythrocyte membranes.

The spontaneous binding of group A streptococcal lipoteichoic acid (LTA) to mammalian cell membranes was studied in isolated membranes of human erythrocytes. The binding of radiolabeled LTA to erythrocyte membranes was dependent on membrane concentration and time. Binding approached a maximum within 30 min of incubation. The bound LTA could be displaced by adding a 50-fold excess of unlabeled LTA. The displaced LTA was eluted from a column of Sepharose 6B in a position identical to that of authentic LTA, suggesting that binding did not alter the size of the molecule. A dissociation constant of 42 micrometers was calculated, and only one population of approximately 5.5 X 10(6) binding sites per erhtyrocyte membrane was detected. Since these results suggested that erythrocyte membranes possess specific binding sites for LTA, an attempt was made to localize the putative receptors to the outside or the inside surface of the erhtyrocyte membrane. Assays of the binding of LTA to resealed right-side-out and inside-out membrane ghosts demonstrated that the outside surface was able to bind over 10 times more LTA than the inside surface. These results support the concept that the membranes possess specific binding sites for LTA and inciate that these binding sites are located almost entirely on the outside surface of erythrocyte membranes.

Binding Sites↗
PubMed1977

Erythrocyte membrane plaques from rats with magnesium deficiency.

This study investigated the anemia of dietary magnesium deficiency in inbred Fisher white rats using freeze-fracture electron microscopy. The plasma membranes of erythrocytes from animals receiving two different magnesium-deficient and control diets were observed at weekly or biweekly intervals for 6 wk. The earliest changes were small plaques on the external surface (ES) and fracture face (PF) of erythrocyte plasma membranes, which occurred after 2 wk of either magnesium-deficient diet. These plaques persisted and increased in size with progressive magnesium deficiency. When fully developed, the plaques consisted of round or oval elevations approximately 30-50 nm in diameter outlined by a narrow raised border. The surface of the plaques was smooth and devoid of intramembranous particles. Incubation of erythrocytes from magnesium-deficient rats in a physiologic solution containing 2 meq/liter magnesium for 1 hr at 37degrees C did not alter the appearance of the plaques. Erythrocytes from control rats, obtained during the same time periods, showed no plaques. Thus, a deficiency of magnesium in rats altered erythrocyte membrane structure.

Animals↗