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At least 19 recordsLinked to original sources
PubMed1989

[Molecular pathology of the erythrocyte membrane. Erythrocyte membrane defects as a cause of congenital hemolytic anemia].

Recently numerous defects of erythrocyte membrane proteins have been described in hereditary hemolytic anemias. An exact biochemical characterization of some different types of hereditary spherocytosis, hereditary elliptocytosis, hereditary pyropoikilocytosis and the hemolytic anemias with increased cation permeability (hereditary stomatocytosis) is possible after analysis of membrane proteins with SDS-polyacrylamide gel electrophoresis, quantitative determination of spectrin, the relation of dimeric to tetrameric spectrin, and partial tryptic digestion of the spectrins. The known clinical heterogeneity of the mentioned disorders is now partially explained by the different biochemical defects of the erythrocyte membrane. In classical hereditary spherocytosis a close relationship between erythrocyte spectrin content and clinical severity has been found. The clinical manifestation in hereditary elliptocytosis and hereditary pyropoikilocytosis mainly depends on the functional disturbance of variant spectrins, especially their ability to form tetramers, i.e. their ability for self-association of the spectrin chains. In the hydrocytic form of stomatocytosis a deficiency of the integral protein band 7.2b has been documented. Besides the analysis of erythrocyte membrane proteins the classical methods used in the study of congenital hemolytic anemias cannot be missed. Signs of increased hemolysis, erythrocyte morphology, osmotic fragility, autohemolysis, heat and mechanical stability of the erythrocyte membrane, intracellular cation concentration and studies of other family members, are indispensable prerequisites for classification, prognosis, and indication of therapeutic efforts, especially splenectomy.

Anemia, Hemolytic, Congenital↗
PubMed1983

Human NADH-cytochrome b5 reductases: comparison among those of erythrocyte membrane, erythrocyte cytosol, and liver microsomes.

NADH-cytochrome b5 reductases purified from human red cell membranes and cytosol were compared with those prepared from human liver microsomes. Minimal molecular weights of the membrane and the cytosol enzymes as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were 36,000 and 32,000 daltons, respectively, which are comparable to those of the detergent-solubilized reductase (dfp) and the protease-solubilized one (tfp) of liver microsomes, respectively. All the enzymes contained FAD and had essentially the same turnover numbers and apparent Km values for NADH and protease-solubilized cytochrome b5. The membrane enzyme and liver dfp reduced cytochrome c in the presence of detergent-solubilized cytochrome b5 70-80 times faster than in the presence of trypsin-solubilized cytochrome b5, whereas the cytosol enzyme and liver tfp showed essentially the same low activities with both preparations of cytochrome b5. SDS-PAGE mapping of the limited proteolytic products of the reductases obtained by digestion with staphylococcal protease or a-chymotrypsin showed essentially the same patterns of peptides between the red cell membrane enzyme and liver dfp and between the red cell cytosol enzyme and liver tfp. These results suggest that the NADH-cytochrome b5 reductase of human red cell membranes is identical with that of liver microsomes and that the enzyme of red cell cytosol is a proteolytic product of the membrane enzyme.

Cytochrome Reductases↗
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↗
PubMed1971

Phospholipid metabolism in intact and modified erythrocyte membranes.

Erythrocyte membranes incorporated labeled phosphate from gamma-adenosine triphosphate (AT(32)P) into phosphatidic acid and the polyphosphoinositides. Inositol-(3)H and palmitate-(14)C were also incorporated into the phospholipids but alpha-glycerophosphate-(32)P was not. The incorporation of gamma-AT(32)P into phospholipids was increased when the erythrocyte ghosts were incubated in hypotonic media which lysed the cells. Lysis had little or no effect on the incorporation of inositol-(3)H and palmitate-(14)C into the phospholipids. If erythrocyte membranes were prepared in 1 mM ethylenediaminetetraacetate (EDTA), instead of 1 mM MgCl(2), then the tonicity of the incubating medium did not influence the incorporation of gamma-AT(32)P into the phospholipids. Erythrocyte ghosts, prepared by lysis in water, EDTA, or 1 mM calcium, lead, mercury, zinc, or cadmium, failed to reconstitute when placed in isotonic medium, inasmuch as they did not retain potassium against a chemical gradient. Ghosts prepared by lysis in 1 mM magnesium, barium, or strontium could be reconstituted. Ghosts which failed to reconstitute incorporated more labeled phosphate from gamma-AT(32)P into the phospholipids than did intact or reconstituted ghosts. The larger incorporation of labeled phosphate by leaky ghosts was not due to a greater entrance of gamma-AT(32)P into those cells. Primaquine phosphate and digitonin, at concentrations which are known to cause cells to form smaller vesicles or to lyse cells by removing cholesterol, did not increase the incorporation of labeled phosphate into the phospholipids. It is suggested that the increased metabolism of phospholipids may be involved in a membrane repair mechanism.

Adenosine Triphosphate↗
PubMed1988

Acidic phosphoproteins associated with the host erythrocyte membrane of erythrocytes infected with Plasmodium berghei and P. chabaudi.

New phosphoproteins appear on the host erythrocyte membrane during Plasmodium berghei and P. chabaudi infection. Distinct proteins having similar properties and all distinguished by isoelectric points of less than 4.0 are identified. Associated with the erythrocyte membranes of P. berghei infected erythrocytes are two proteins with molecular masses of 65 and 46 kDa, whereas 93, 90 and 76 kDa proteins are observed during P. chabaudi infection. These new erythrocyte membrane associated proteins are all of parasite origin as indicated by metabolic labeling with proline and are synthesized during the ring stage of the asexual replicative cycle. Three of these proteins, the 93 kDa P. chabaudi protein and both P. berghei proteins, have been purified and the amino acid composition determined. All three are characterized by a relatively high proportion of aspartate and glutamate residues. Mono-and polyclonal antibodies were also raised against the same three purified proteins. No cross reactivity between these three proteins is observed, but one monoclonal antibody against the 65 kDa P. berghei crossreacts with a 27 kDa mouse erythrocyte protein. Immunofluorescence using the antibodies in combination with subcellular fractionation studies clearly shows that these phosphoproteins are associated with the host erythrocyte membrane and not the parasite.

Animals↗
PubMed2003

Antimicrobial activity of N-acylphenothiazines and their influence on lipid model membranes and erythrocyte membranes.

The antibacterial activity and influence on lipid model membranes and erythrocyte membranes of 24 N-acylphenothiazines and trifluoperazine were studied. (1) Among 24 phenothiazines, the antimicrobial activity of amino maleates was the highest. (2) The influence of phenothiazines on model liposome and erythrocyte membranes was studied using N-phenyl-1-naphthylamine (NPN) as fluorescence probe. From the three types of phenothiazine substitution (H, Cl, CF3) at position 2, CF3-phenothiazines were the most effective in the interaction with liposomal membranes. (3) As measured by the polarization degree of 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence, the alteration of membrane fluidity induced by CF3-phenothiazines was the biggest. Surprisingly, phenothiazines induced stomatocytic shape alterations (invaginations) in erythrocytes and at higher concentrations, also hemolysis of erythrocytes was observed. (4) The microcalorimetic measurements of influence of phenothiazines on thermal behaviour of synthetic lipid systems confirmed the previously obtained results. The main transition temperature and enthalpy of transition of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) were significantly modified by CF3-phenothiazines, suggesting their penetration of the lipid bilayer. Above results show that phenothiazine maleates were generally more effective than other phenothiazines used in this study.

Anti-Bacterial Agents↗
PubMed1989

Cystic fibrosis: II. Altered microviscosity of erythrocyte membrane.

Erythrocyte membrane fluidity alterations in cystic fibrosis are described. The relative flexibility of the membrane was studied using lipid spin label, i.e. methyl-5-doxylpalmitate (M5DP), and pyrene as a fluorescence probe. It was found that there was a decrease of membrane fluidity in the hydrophobic midzone of the membrane, probed by pyrene, as well as at the hydrophilic surface region, probed by M5DP.

Child↗
PubMedDate not supplied

Combined effects of lead and EDTA on Na+,K+-ATPase activity of erythrocyte membranes.

Erythrocyte Na+,K+-ATPase activity increased significantly in lead workers of a lead refining factory when measured with EDTA and compared to the controls without EDTA. The enzyme activity measured with EDTA increased in the following order: controls less than office workers in a lead refining factory less than lead workers. A positive correlation existed between blood lead and enzyme activity with EDTA (r = 0.380, p less than 0.10), and the activity without EDTA (r = 0.398, p less than 0.05). A negative correlation was found between sodium in erythrocytes and enzyme activity with EDTA (r = -0.437, p less than 0.05), and the activity without EDTA (r = -0.416). But no relationship was observed between enzyme activities and potassium in erythrocytes. A positive correlation between enzyme activity with EDTA and that without EDTA was observed (r = 0.452, p less than 0.05). With addition of lead to fragments of erythrocyte membranes, a significant decrease occurred in the activity of the enzyme without EDTA, whereas no change was observed with EDTA. No significant change occurred in the enzyme activity with and without EDTA upon addition of lead to blood. The maximum level of lead in membrane fragments (lead combined with membranes) of workers exposed to lead was 0.60 microgram/mg protein, and that in the experiment of addition to blood was 7.0 micrograms/mg protein.

Adult↗
PubMed1985

The effects of dietary omega-3 polyunsaturated fatty acids on erythrocyte membrane phospholipids, erythrocyte deformability and blood viscosity in healthy volunteers.

We have examined, in normal subjects, the effects of a daily dietary supplement of fish oil concentrate ('maxEPA'), providing 3 g of omega-3 fatty acids, on erythrocyte membrane phospholipids, erythrocyte deformability and blood viscosity. After 3 weeks, incorporation of C20:5 omega 3 into erythrocyte phosphatidyl choline (PC) was greater compared to phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS). After 6 weeks, there was no further increase in total erythrocyte C20:5 omega 3, but its distribution amongst phospholipid subclasses had changed. C20:5 omega 3 had increased further in PE and PS, but decreased in PC. Incorporation of C20:5 omega 3 also occurred into PC, PE and PS. omega-3 Fatty acids were incorporated almost entirely at the expense of C18:2 omega 6, but total unsaturation of phospholipids was increased. This is consistent with increased lipid fluidity, which may be an important determinant of erythrocyte deformability. The same dosage of maxEPA also resulted in a significant increase in erythrocyte deformability and a concomitant reduction in whole blood viscosity. Since plasma viscosity and haematocrit were unchanged it seems likely that the effects on blood rheology were mediated by changes in erythrocyte lipid fluidity. Modification of blood rheology by dietary omega-3 fatty acids is of potential value in the treatment of vascular disease.

Blood Viscosity↗
PubMed1998

Biochemical analysis of potential sites for protein 4.1-mediated anchoring of the spectrin-actin skeleton to the erythrocyte membrane.

Erythrocyte protein 4.1 has been hypothesized to link the spectrin-actin junctional complex directly to the cytoplasmic domain of glycophorin C, but this bridging function has never been directly demonstrated. Because an alternative protein-mediated bridge between the junctional complex and the cytoplasmic domain of band 3 is also plausible, we have undertaken to characterize the membrane sites to which protein 4.1 can anchor the spectrin and actin skeleton. We demonstrate that proteolytic removal of the cytoplasmic domain of band 3 has minimal effect on the ability of protein 4.1 to promote 125I-labeled spectrin and actin binding to KI-stripped erythrocyte membrane vesicles. We also show that quantitative blockade of all band 3 sites with either monoclonal or polyclonal antibodies to band 3 is equally ineffective in preventing protein 4.1-mediated association of spectrin and actin with the membrane. In contrast, obstruction of protein 4.1 binding to its docking site on the cytoplasmic pole of glycophorin C is demonstrated to reduce the same protein 4.1 bridging function by approximately 85%. We conclude from these data that (i) glycophorin C contributes the primary anchoring site of the protein 4.1-mediated bridge to the spectrin-actin skeleton; (ii) band 3 is incapable of serving the same function; and (iii) additional minor protein 4.1 bridging sites may exist on the human erythrocyte membrane.

Actins↗
PubMed1990

[Changes in several characteristics of the erythrocyte membrane and erythrocyte structure in severe burns in animal experiments].

It is determined in experiments on rats that the IIIB degree thermal injuries of 20% of the total body surface significantly reduce the erythrocytic membrane's resistance and cause the production of peroxides in 15 minutes after trauma. Simultaneously the electrical properties begin to change. The structure of erythrocytes is also altered. In 30 minutes post injury these alterations are in progress, but in 60 minutes they are less expressed. The structure of the erythrocytes is significantly altered. The authors consider that the influence of membranotoxic factors--the products of free radicals' reactions and phospholipases--is accounted for all noticed alterations.

Animals↗
PubMedDate not supplied

[The effect of ionizing radiation on Ca ATPase of erythrocyte membranes].

Erythrocyte ghosts were irradiated with doses of 4 x 10(-3)-10(3) Gy. The activity of Ca(2+)-ATPase, the kinetic characteristics of enzyme reaction, the Hill's coefficient, the association constant and a number of La3+ linking centers were determined. The structural--functional peculiarities of Ca(2+)-ATPase changes under exposure to 4 x 10(-3) and 40 Gy of ionizing radiation have been established.

Calcium-Transporting ATPases↗
PubMed1995

Immunochemical studies on red cell auto antigens: use and limits of immunoprecipitation from biotinylated erythrocyte membrane.

Erythrocyte surface was labelled by means of biotin; immunoprecipitation technique was then used to localise antigens recognised on red cell membrane proteins by: a) autoantibodies from 13 patients with antierythrocyte autoimmunity; b) commercially available anti-D and anti-k (Cellano) antierythrocyte alloantibodies. Results with alloantibodies are comparable to those obtained using radiochemical probes. Immunoprecipitations with autoantibody containing eluates showed reactivity at different molecular weights (the most common at 34-50 kD, others at 100 and 45 kD and a newly described one at 80 kD), thus confirming that many membrane proteins may act as target antigens for erythrocyte autoimmunity. We found a higher percentage of reactive immunoprecipitates than previously reported using the same labelling method. However, critical conditions to allow valuable results seem to be a threshold amount of autoantibody to precipitate any recognisable band and the sensitivity of the detection method. Hence methodological variables must be taken into consideration before concluding that "non protein" antigens trigger the autoimmune process.

Autoantigens↗
PubMed2000

Enzymatic removal of oxidized protein aggregates from erythrocyte membranes.

Erythrocytes oxidized or aged in the circulation undergo membrane protein aggregation and anti-band 3 autoantibody binding to the cell surface. When human erythrocytes were mildly oxidized in vitro with 0.1 mM Fe(III) at 37 degrees C for 3 h, the aggregation of nonionic detergent C(12)E(8)-insoluble membrane protein and the binding of anti-band 3 IgG to the cell surface were increased. Incubation of membranes isolated from the oxidized cells increased the amount of protein aggregates by 5-fold after 6 h, while incubation for a further 12 h sharply decreased the amount of aggregates. In the presence of diisopropyl fluorophosphate (DFP), however, the increased amount of aggregates was maintained in the subsequent incubation. Western blot analysis of the aggregates using rabbit anti-band 3 showed that band 3 protein aggregates increased in the initial stage of incubation and decreased upon subsequent incubation, whereas the increased band 3 protein aggregates did not subsequently decrease when membranes were incubated in the presence of DFP. Incubation of the oxidized cells at 37 degrees C for 18 h caused reduction of the membrane protein aggregates and the (125)I-anti-band 3 IgG binding to the cell surface, while incubation in the presence of DFP did not cause these reductions. The results suggest that the oxidation-induced cell membrane protein aggregates were probably removed by 80-kDa serine protease, namely, oxidized protein hydrolase (OPH), in the oxidized cell membranes [Fujino et al. (1998) Biochim. Biophys. Acta 1374, 47-54; (1998) J. Biochem. 124, 1077-1085; (2000) Biochim. Biophys. Acta 1478, 102-112], and as a result the increased anti-band 3 binding to the cell surface was reduced.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1983

Effect of factors of favism on the protein and lipid components of rat erythrocyte membrane.

Erythrocytes prepared from riboflavin- and tocopherol-deficient (RT-) and from control rats were used to investigate the mechanism of oxidative hemolysis by the factors of favism. RT- erythrocytes have a defense system against the oxidative stress which is blocked either where regeneration of GSH occurs or the scavenging of the radicals from the membrane is prevented. The oxidative factors used were isouramil, divicine and diamide. When RT- erythrocytes were treated with isouramil, GSH decreased to undetectable levels and was not regenerated. Complete hemolysis occurred, but no oxidation of SH groups of membrane proteins or formation of spectrin polymers was detected. A similar effect was observed with diamide. However, SH groups of membrane proteins were completely oxidized and spectrin polymers were formed. Extensive lipid peroxidation was also detected together with a 30% fall in the arachidonic acid level. Control erythrocytes treated with either isouramil or diamide were not hemolyzed. When treated with isouramil, after a fall in the first few minutes, the GSH level was completely regenerated after 20 min. Incubation with diamide caused extensive oxidation of SH groups of membrane proteins and formation of spectrin polymers. No lipid peroxidation was detected after treatment with isouramil, but the same decrease of arachidonic acid occurred as in RT- erythrocytes. These results support the hypothesis that oxidative hemolysis by the factors of favism is caused by uncontrolled peroxidation of membrane lipids.

Animals↗
PubMed1976

Biochemical studies on abnormal erythrocyte membranes. Protein abnormality of erythrocyte membrane in biliary obstruction.

Biochemical studies on erythrocyte membranes from eleven obstructive jaundice patients (due to various disorders) have been undertaken, By scanning electron microscopic observation these erythrocytes were spur and target in appearance. The lipid composition showed a marked increase in both cholesterol and phosphatidylcholine. In addition to these changes, it was unexpectedly demonstrated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate that a specific membrane protein component 4.2 was reduced or absent in all cases tested. This membrane protein abnormality was identical with that of hereditary spherocytosis erythrocyte membranes. It is of particular interest to note that after surgical relief of biliary obstruction in a typical case of common duct cholelithiasis, the disc electrophoretic pattern of erythrocyte membranes became normal and both lipid composition and red cell morphology returned to normal.

Cholestasis↗