American Society of Hematology

Figure 2

$Figure 2. Current model of the red cell membrane. Most of the known protein contacts are shown, but the relative positions of the proteins to each other within the various complexes are mostly not known. The major proteins are drawn roughly to scale, but the shapes are mostly imaginary. Approximately 40% of the band 3 molecules are tetramers in a complex with ankyrin and other integral proteins near the spectrin self-association site (Ankyrin complex). An approximately similar fraction of the band 3 molecules, probably dimers, are located near the spectrin-actin junction and bind to spectrin via protein 4.1R (4.1), protein 4.2 (4.2), and adducin (Actin junctional complex). As described later in the text, it is likely that these 2 complexes, with their associated proteins, are large enough that they sometimes contact each other. The remaining band 3 dimers float untethered within the lipid bilayer (Unbound band 3). The actin protofilament lies parallel to the membrane. The complexes of proteins associated with band 3 are not constant; that is, some proteins are present in much smaller numbers than others (eg, Kell, Kx, CD44, CD47, DARC/Duffy, LW, phosphofructokinase, and aldolase). The amounts of p55, adducin, and dematin are also insufficient to interact with all the spectrin/protein 4.1/actin complexes. As a consequence, the ankyrin and actin junctional complexes must vary in composition and mobility. For visual clarity, peroxiredoxin 2 (Prx2) is shown attached only to unbound band 3, but there is no evidence for this selectivity. CH, calponin homology; CH1 and CH2, actin binding domains of β-spectrin; EF, calcium ion–binding EF hand domain of α-spectrin; F-actin, filamentous actin; GEC, glycolytic enzyme complex (glyceraldehyde-3-phosphate dehydrogenase, phosphofructokinase, lactic dehydrogenase, pyruvate kinase, aldolase, and enolase); Glut1, glucose transporter 1; GPA, glycophorin A; GPB, glycophorin B; GPC/D, glycophorins C and D; LW, Landsteiner-Wiener; RhAG, Rh-associated glycoprotein. Professional illustration by Somersault18:24. Adapted from Korsgren et al5 with permission.$

Current model of the red cell membrane. Most of the known protein contacts are shown, but the relative positions of the proteins to each other within the various complexes are mostly not known. The major proteins are drawn roughly to scale, but the shapes are mostly imaginary. Approximately 40% of the band 3 molecules are tetramers in a complex with ankyrin and other integral proteins near the spectrin self-association site (Ankyrin complex). An approximately similar fraction of the band 3 molecules, probably dimers, are located near the spectrin-actin junction and bind to spectrin via protein 4.1R (4.1), protein 4.2 (4.2), and adducin (Actin junctional complex). As described later in the text, it is likely that these 2 complexes, with their associated proteins, are large enough that they sometimes contact each other. The remaining band 3 dimers float untethered within the lipid bilayer (Unbound band 3). The actin protofilament lies parallel to the membrane. The complexes of proteins associated with band 3 are not constant; that is, some proteins are present in much smaller numbers than others (eg, Kell, Kx, CD44, CD47, DARC/Duffy, LW, phosphofructokinase, and aldolase). The amounts of p55, adducin, and dematin are also insufficient to interact with all the spectrin/protein 4.1/actin complexes. As a consequence, the ankyrin and actin junctional complexes must vary in composition and mobility. For visual clarity, peroxiredoxin 2 (Prx2) is shown attached only to unbound band 3, but there is no evidence for this selectivity. CH, calponin homology; CH1 and CH2, actin binding domains of β-spectrin; EF, calcium ion–binding EF hand domain of α-spectrin; F-actin, filamentous actin; GEC, glycolytic enzyme complex (glyceraldehyde-3-phosphate dehydrogenase, phosphofructokinase, lactic dehydrogenase, pyruvate kinase, aldolase, and enolase); Glut1, glucose transporter 1; GPA, glycophorin A; GPB, glycophorin B; GPC/D, glycophorins C and D; LW, Landsteiner-Wiener; RhAG, Rh-associated glycoprotein. Professional illustration by Somersault18:24. Adapted from Korsgren et al⁵ with permission.

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