The band 3 protein of the human red cell membrane: a review

Congenital dyserythropoietic anaemia type II (HEMPAS): a family study

A family having two affected siblings with congenital dyserythropoietic anaemia type II (HEMPAS) is described. The proband was diagnosed after referral for investigation of haemolytic anaemia. Clinical evaluation and in vivo red cell (RBC) survival and the sequestration studies in the proband indicated that the anaemia was due to a combination of ineffective erythropoiesis and premature destruction of RBCs in the spleen. Scanning electron microscopic examination of peripheral RBCs was undertaken and is reported. The polypeptide composition of RBC membranes was also examined using polyacrylamide gel electrophoresis after solubilisation in sodium dodecyl sulphate. These results are also reported.

Contribution of whole cell and cytoplasmic polypeptides to apparent red cell membrane alterations

We have compared densitometric tracings of whole cell, cytoplasmic and membrane polypeptide electrophoretic patterns in an attempt to distinguish atypical partitioning from intrinsic membrane polypeptide changes occurring as a result of reticulocyte enrichment, metabolic depletion, N-ethylmaleimide treatment and hereditary xerocytosis. We report that membrane alterations seen in a reticulocyte-enriched population of normal cells are present in the whole cells prior to membrane isolation. Some of the membrane alterations in metabolically depleted cells and all of those in N-ethylmaleimide-treated cells are traced to modifications in tary xerocytosis. We report that membrane alterations seen in a reticulocyte-enriched population of normal cells are present in the whole cells prior to membrane isolation. Some of the membrane alterations in metabolically depleted cells and all of those in N-ethylmaleimide-treated cells are traced to modifications in the partitioning of polypeptides between membranes and supernatant (cytoplasm) at hemolysis. The power of this approach in resolving the sources of apparent red cell membrane protein alterations is demonstrated in studies with hereditary xerocytes. Suggested altered partitioning of these cells described earlier (Sauberman, N., Fortier, N.L., Fairbanks, G., O'Connor, R.J. and Snyder, L.M. (1979) Biochim. Biophys. Acta 556, 292-313) is further documented and found to be unrelated to the younger cell population or slight metabolic depletion that occurs during the washing of xerocytes prior to hemolysis.

Enhancement of anion equilibrium exchange by dansylation of the red blood cell membrane

Dansylation of resealed red cell ghosts enhances the band 3 protein-mediated equilibrium exchange of sulfate ions. After dansylation, the specific anion transport inhibitor 4,4'-diisothiocyanato-dihydrostilbene 2,2'-disulfonate (H2DIDS) is still capable of combining with its original binding site on the band 3 protein and of producing the same high degree of inhibition of sulfate exchange as in the untreated red cell ghost. Nevertheless, dansylation causes allosteric effects at the H2DIDS-binding site that exhibit themselves by an increased susceptibility to dinitrophenylation of one of the amino acid residues that is involved in the covalent bond formation with H2DIDS and a decrease of the apparent KI values for two reversibly acting inhibitors that are known to produce their effects at the H2DIDS-binding site of the band 3 protein. The degree of enhancement of divalent anion exchange depends on both the pH that existed during dansylation and the pH at which the anion equilibrium exchange across the dansylated membrane is measured. The effect of dansylation reaches a broad maximum around ph 6.6. In untreated ghosts, divalent anion equilibrium exchange passes through a maximum around pH 6.3. After dansylation under optimal conditions at pH 6.6, anion equilibrium exchange as measured below the maximum of pH 6.3 is much less enhanced than above the maximum. Under suitable experimental conditions, the maximum may be replaced by a plateau that extends up to at least pH 8.5. At this pH, the enhancement is about 100-fold. Thus, the pH dependence of divalent anion exchange becomes more similar to that of monovalent anion exchange. The apparent activation enthalpies for sulfate-equilibrium exchange across the modified membrane, as measured at pH 6.3 and 7.9, are indistinguishable, independent of temperature between 0 and 37 degrees C and amount to 146 kj/mol. This is similar to the activation enthalpies measured in the untreated membrane. The mode of action of dansyl chloride is discussed on the basis of currently considered mechanisms of divalent anion transport, for which the pertinent equations are presented.

Rotational diffusion of band 3 proteins in membranes from En(a-) and neuraminidase-treated normal human erythrocytes

Recent experiments have demonstrated an association between band 3 and glycophorin A in the human eythrocyte membrane (Nigg, E.A., Bron, C., Girardet, M. and Cherry, R.J. (1980) Biochemistry 19, 1887-1893). Here, the influence of sialoglycoproteins on the rotational diffusion of band 3 in the human erythrocyte membrane was investigated by studying membranes from En(a-) and neuraminidase-treated erythrocytres. Rotational diffusion was measured by observing flash-induced transient dichroism of eosin-labeled band 3. Although erythrocytes of the rare phenotype En(a-) lack the major sialoglycoprotein, glycophorin A, no significant difference in band 3 rotation at pH 7.4 and 37 degrees C could be detected between En(a-) and normal erythrocyte membranes. Band 3 rotation at pH 7.4 was also insensitive to the enzymatic removal of sialic acid from the surface of normal erythrocytes. Moreover, the existence of an essentially similar temperature-dependent equilibrium between band 3 proteins with different mobilities was observed in normal, En(a-) and neuraminidase-treated erythrocytes. From these results it is concluded that glycophorin A contributes less than 15% to the cross-sectional diameter of the band 3-glycophorin A complex in the plane of the normal membrane. The rotation of the complex at pH 7.4 is not significantly influenced by either steric or electrostatic interactions involving the oligosaccharide moiety of glycophorin A.

Biosynthesis of erythrocyte membrane protein band 3 in DMSO-induced Friend erythroleukemia cells

The major integral membrane protein of red blood cells, the mouse equivalent of human band 3, was purified and used to raise a specfic antiserum. The murine protein resembles its human counterpart in several of its properties, including susceptibility to digestion by chymotrypsin added to intact cells and an ability to bind to concanavalin A. The synthesis of 35S-labeled band 3 was detected in Friend erythroleukemia cells treated with DMSO by immuneprecipitation followed by SDS gel electrophoresis and fluorography. Induction with DMSO led to a greater than tenfold increase in the synthesis of band 3 and maximal synthesis was reached 3 to 4 days after the beginning of induction.

Interactions of band 3-protein from human erythrocyte membranes with phospholipid monolayers at the air-water interface

Lipid monolayers at the air-water interface were used as a model system to study the interactions of solubilized band 3-protein of the human erythrocyte membrane with phospholipids. The changes in monolayer surface pressure accompanying protein incorporation were used as a measure of the strength of the protein-lipid interactions. The following results were obtained: (1) Both polar and apolar forces contribute to the protein-lipid interactions, the latter being predominant. (2) The interactions strongly depend on the pH of the monolayer subphase. They are much stronger at acid than at neutral or alkaline pH. (3) The influence of pH on the band 3-phospholipid interactions is mainly due to a pH-induced conformational change of the protein, the pK value of which is near 5.0. (4) At all pH values studied, band 3 shows the highest affinity for phosphatidic acid and phosphatidylglycerol, the lowest for sphingomyelin and phosphatidylcholine.

Cytoskeletal network underlying the human erythrocyte membrane. Thin-section electron microscopy

A filamentous network underlying the human erythrocyte membranes can be clearly visualized in situ by electron microscopy of thin sections of specimens fixed with tannic acid-glutaraldehyde. The network is composed of two layers: the first, a layer of vertical components with granular appearance, which are seen to be directly associated with the membrane proper, and the second, a horizontally disposed, anastomosing meshwork of filamentous components, approximately 9 nm in thickness, which are attached to the vertical components. The diameter and appearance of the filamentous components are similar to those of purified spectrin. EDTA treatment (0.1 mM, pH 8.0), which was used to extract spectrin and actin, resulted in the disappearance of the filamentous meshwork, leaving only the granular components.

An immunological study of band 3, the anion transport protein of the human red blood cell membrane

Band 3, the predominant membrane-spanning polypeptide and purported anion transport protein of human red cells, was isolated by a new procedure which utilized selective solubilization and anion exchange chromatography on Affi-Gel 102 in 0.5% and Triton X-100/0.03% sodium dodecyl sulfate. Rabbit anti-serum prepared against the purified protein reacted with human and monkey band 3 but gave no immunoprecipitate with membrane proteins from several non-primate species. The antiserum was directed solely towards a portion of the cytoplasmic pole of the band 3 polypeptide contained within a 23,000 dalton amino-terminal fragment, as shown by agglutination, absorption, double diffusion and immunoprecipitation techniques. Saturation of both surfaces of resealed erythrocyte ghosts with the anti-band 3 antiserum had no significant effect on chloride transport. Our data define the topographically-limited immunogenicity of human band 3 in rabbits, demonstrate a lack of immunological cross-reactivity of band 3 between primates and non-primates, and support the hypothesis that the cytoplasmic domain of band 3 is not intimately involved in anion transport.

Effect of adenosine on concanavalin A agglutination of human erythrocytes

We have attempted to correlate the functional activity of protein 3 with its activity as a receptor for concanavalin A. The concanavalin A agglutination of human erythrocytes is enhanced by adenosine. It varies with time of storage of the blood and is dependent on the concentration of adenosine in the medium. Adenine and/or inosine, which increase cellular ATP, do not substitute for adenosine in enhancing agglutination, and adenosine enhances agglutination of fresh erythrocytes with normal levels of ATP. Thus, it appears that cellular ATP levels are not directly involved in modulation of concanavalin A agglutination by adenosine. Trypsin, which hydrolyzes most of the exposed proteins of the cell surface but does not alter protein 3, enhances concanavalin A agglutination without altering the relative response to the cell to adenosine. Glucose, as well as the glucose transport inhibitors maltose and cellobiose, inhibits agglutination. High concentrations of adenosine reverse the inhibition by glucose and enhance agglutination in the presence of maltose and cellobiose. Treatment of erythrocytes with 4,4'-diisothiocyanostilbene-2,2-disulfonic acid disodium salt, which selectively inhibits the anion transport function of protein 3, substantially inhibits adenosine-supported concanavalin A agglutination. Treatment of erythrocytes with iodoacetate under conditions in which it selectively reacts with glyceraldehyde-3-phosphate dehydrogenase inhibits agglutination. Adenosine protects this dehydrogenase in erythrocytes from inactivation by iodoacetate, over the same concentration range in which it enhances agglutination.

Red cell membrane protein phosphorylation in hemolytic anemias and muscular dystrophies

We review our current understanding of membrane phosphorylation in normal and abnormal erythrocytes. The major phosphoproteins in red blood cell (RBC) membranes are spectrin (band 2), bands 3, 2.1, and 4.5, and glycophorin A. At least two protein kinases can be distinguished on the basis of their stimulation by cyclic AMP and salt; they are present both in the membrane and in the cytosol. Analysis of the conflicting data on endogenous membrane-protein phosphorylation in abnormal RBCs indicates a considerable variability of phosphorylation rates which largely depends on the manner of preparation of ghosts and enzyme assay conditions. This variability reflects differences in the partitioning of protein kinases between the membrane and cytosol, the specificity and accessibility of membrane-protein substrates, and reaction kinetics. We select examples of data from several hemolytic anemias to illustrate that precautions are needed to interpret abnormalities of membrane-protein phosphorylation properly; we discuss possible new methodological approaches.

Analysis of human erythrocyte membrane vesicles produced by shearing

Shearing of ghosts in a French pressure cell produces three classes of microvesicles that differ from endocytic vacuoles, exocytic vacuoles, and inside-out vesicles. It was thought that an analysis of these vesicles might provide some clues about the assembly of proteins within the human erythrocyte membrane. The microvesicles were separated into three visible bands, labeled top, middle, and bottom, and assayed for activity of Mg++-ATPase, Na+,K+-ATPase, acetylcholinesterase, glyceraldehyde-phosphate dehydrogenase, and NADH oxidoreductase. Their proteins were also characterized by polyacrylamide gel electrophoresis with both Coomassie blue staining, to assess total protein content and distribution, and PAS-staining, to characterize sialoglycopeptides. In order to minimize problems inherent in ghost preparation, Dodge or hypotonic ghosts and glycol or isotonic ghosts were used in all studies. Middle membrane vesicles most resembled intact ghosts. Top vesicles had reduced levels of NADH oxidoreductase and more PAS-2 at the expense of PAS-1. The bottom vesicle class was very much enriched with PAS-1 at the expense of PAS-2, and PAS-3 was completely absent. In addition bottom vesicles had highest NADH oxidoreductase activity but lowest activity of all the other enzymes measured. These vesicle classes could not have been produced by tangential shearing through the membrane, nor could radial shearing through a membrane in which all proteins were free to move laterally have accounted for the three discrete vesicle classes or for their different patterns of enzymes and proteins. The analysis of the microvesicles produced by shearing is most consistent with radial shearing through membranes where there may be fixed domains superimposed on the basic fluid-mosaic structure.

Self-association of band-protein from human erythrocyte membranes in aqueous solutions

Band 3, the main integral protein of the human erythrocyte membrane, was solubilized and purified in high concentrations of acetic acid. After removal of the organic solvent by dialysis, the self-association of the protein in aqueous solutions was studied by analytical ultracentrifugation. Sedimentation velocity and sedimentation equilibrium experiments clearly demonstrate that, under appropriate conditions of protein preparation, at protein concentrations c less than 200 micrograms/ml, ionic strengths 2 less than 10mM and pH values remote from the isoelectric pH of the protein, band 3 shows a monomer/dimer/tetramer-association equilibrium. With some preparations, as well as at higher values of c or I, hexamers and octamers contribute to the association equilibrium. The time needed for relaxation towards association equilibrium depends on the blood donor from whom the membranes were derived and varies between less than one minute and more than several hours. The results of analytical ultracentriguation, together with previously published data on the incorporation of band 3 into planar lipid bilayers, from chemical crosslinking and from electronmicroscopy suggest that band 3 will also show a monomer/dimer/tetramer-association equilibrium in the human erythrocyte membrane. This hypothesis contrasts the widely-held assumption that, in the membrane, band 3 is a stable dimer; however, it is consistent with nearly all known data on band 3-self-association.

Fine structure of the band 3 protein in human red cell membranes: freeze-fracture studies

The major red cell membrane protein, band 3, is a glycoprotein which extends across the membrane from the extracellular space into the cytoplasmic compartment. It is widely held that band 3 is a component of the intramembrane particles (IMP) which can be demonstrated by freeze-fracture electron microscopy. In this study, we find that the outer surface poles of the IMP can be seen by freeze-etching after they are unmasked by proteolysis under conditions which excise the surrounding sialopeptides from the membrane. The poles appear as distinctive projections, 30--50 A in diameter, the "ES particles." The ES particles remain associated with the outer surface of the membrane following cleavage of the band 3 polypeptide by chymotrypsin or pronase. This is consistent with previous biochemical studies which have shown that the 38,000-dalton outer surface segment of band 3 is intercalated in the lipid bilayer. A granulofibrillar component at the inner surface of the membrane is provisionally identified as the 40,000-dalton inner-surface domain of band 3.