Erythrocyte membrane, ‘band 3’ protein

Erythrocyte membranes band 3 protein 420 proteins of 403 Erythrose 163s Erythrulose 164s Escherichia coli 3... 

Isothiocyanate derivatives of stilbene sulfonates have been utilized with marked success as affinity labels for an anion transport protein of the erythrocyte membrane by Rothstein and his associates, - and glucosyl isothiocyanate has been employed to label a glucose transport protein of the human erythrocyte membrane. Both proteins fall in the 90,000-100,000 dalton range (band 3 in the terminology of Fairbanks et oZ. ). In both cases, transport has been reconstituted using phospholipid vesicles and a band 3 preparation - after aflBnity labeling with the appropriate isothiocyanate had provided preliminary evidence that this protein class might be involved in transport. 

Figure 3. Critical concentration behavior of actin self-assembly. For the top diagram depicting the macroscopic critical concentration curve, one determines the total amount of polymerized actin by methods that measure the sum of addition and release processes occurring at both ends. Examples of such methods are sedimentation, light scattering, fluorescence assays with pyrene-labeled actin, and viscosity measurements. Forthe bottom curves, the polymerization behavior is typically determined by fluorescence assays conducted under conditions where one of the ends is blocked by the presence of molecules such as gelsolin (a barbed-end capping protein) or spectrin-band 4.1 -actin (a complex prepared from erythrocyte membranes, such that only barbed-end growth occurs). Note further that the barbed end (or (+)-end) has a lower critical concentration than the pointed end (or (-)-end). This differential stabilization requires the occurrence of ATP hydrolysis to supply the free energy that drives subunit addition to the (+)-end at the expense of the subunit loss from the (-)-end.

Figure 8. Infrared spectra of erythrocyte membranes (a) in D2O-0.1 M NaCl for 1.5 hours and (b) dry. The amide I band of the wet material shows a shoulder at 1650 cm. 1, which may arise from a-helical protein...

One of the major integral proteins of the erythrocyte membrane is the anion channel, or band-3 protein, which moves Cl- and HC03 anions across the membrane. The anion transporter has two identical subunits with molecular weights of about 95,000, and each subunit probably has 10 or 11 transmembrane helices. The band-3 protein is attached to the spectrin cytoskeleton through a smaller protein, anky-rin. The cytosolic domain of the anion transporter also binds the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase. 

Vanadate transport in the erythrocyte was shown to occur via facilitated diffusion in erythrocyte membranes and was inhibited by 4,4 -diisothiocyanostilbene-2,2 -disulfonic acid (DIDS), a specific inhibitor of the band 3 anion transport protein [23], Vanadium is also believed to enter cells as the vanadyl ion, presumably through cationic facilitated diffusion systems. The divalent metal transporter 1 protein (called DMT1, and also known as Nramp2), which carries iron into cells in the gastrointestinal system and out of endosomes in the transferrin cycle [24], has been proposed to also transport the vanadyl cation. In animal systems, specific transport protein systems facilitate the transport of vanadium across membranes into the cell and between cellular compartments, whereas the transport of vanadium through fluids in the organism occurs via binding to proteins that may not be specific to vanadium. 

Pimplikar, S.W. Reithmeier, R.A. Affinity Chromatography of Band 3, The Anion Transport Protein of Erythrocyte Membranes. J. Biol. Chem. 1986, 261, 9770-9778. 

Figure 1 shows heat capacity profiles of human erythrocyte ghosts Incubated with Increasing concentrations of pyran copolymer In 310 Imosm phosphate buffer. The five endothermic transitions of the control sample (bottom curve) are labeled A, B2j C and D, In accord with earlier work by Brandts and coworkers (13-16) and from this laboratory (17-20). The A transition Is assigned quite securely as a partial denaturation of spectrin, the major cytoskeletal protein on the erythrocyte membrane (13). Bj. and B2 appear to Involve proteins and lipids (protein Bands IV.1 and... 

As promised, let us now remove the constraints on the permeability of the membrane to other solutes. For clarity, however, let us do so in a stepwise fashion. Figures 3a-d show the effect on erythrocytes when the cells are placed in isosmotic ammonium chloride or sodium propionate and chloride anion is allowed to exchange for bicarbonate anion. The erythrocyte membrane has an intrinsic protein called Band 3 (after its position in gel electrophoresis) which permits the rapid exchange of chloride anion for bicarbonate anion. In the presence of physiological concentrations of medium bicarbonate (24 mM/L) the half-time for exchange is... 

Indications of nonenzymatic glycosylation of red cell membrane proteins was first reported in 1976 (B2). Analysis of the various protein components of the erythrocyte membrane indieated that glycosylation of red cell ghosts in 18 diabetics was twice that in normal individuals and correlated with levels of Hb Ajj. (M25). Comparison of individual membrane protein bands on sodium dodecyl sulfate-polyacrylamide electrophoresis did not indicate any... 

Band 3 Protein - the most abundant erythrocyte membrane protein. It is an anion channel which facilitates the exchange of HCOSTor Ck. 

Glycoproteins of the human erythrocyte membrane, including glycophorin A and band 4.5 have been identified as two major classes of methyl-acceptor polypeptides for the enzyme, protein methylase II (.S -adenosylmethionine protein carboxy 0-methyl transferase, EC 2.1.1.24). ... 

Treatment of human erythrocyte membranes with Cu -2-phenanthroline at 0 °C results in the cross-linking of the Band 3 polypeptide to a dimer. The cross-linked protein was digested with proteolytic enzymes and the products were resolved by two-dimensional gel electrophoresis. The thiol groups involved in the cross-linking were identified. 

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