Abstract
Protein 4.1 is an important structural component of the erythrocyte membrane. In contrast to our detailed understanding of the role of protein 4.1 in regulating membrane mechanical properties through modulation of spectrin-actin interaction, very little is known regarding the functional implications of protein 4.1 interaction with band 3. In the present study, we explored the potential role of protein 4.1-band 3 interaction in modulating membrane mechanical properties. Based on recent studies which identified the sequence motif IRRRY in band 3 as the protein 4.1 interacting domain, we studied the functional consequences of specific dissociation of band 3-protein 4.1 interaction by the synthetic peptide IRRRY. We show that protein 4.1 bound to the inside-out vesicles could be dissociated from band 3 but not from glycophorin C by IRRRY. Furthermore, incorporation of IRRRY into resealed ghosts resulted in decreased membrane deformability and increased membrane mechanical stability. The observed alterations in membrane properties appears to result from increased band 3-ankyrin interaction following dissociation of protein 4.1 from band 3. These studies have enabled us to identify an important functional role for band 3-protein 4.1 interaction in modulating erythrocyte membrane properties.
Highlights
Protein 4.1 is an important structural component of the erythrocyte membrane
We explored the potential role of protein 4.1-band 3 interaction in modulating membrane mechanical properties by studying the functional consequences of specific dissociation of band 3-protein 4.1 interaction using the synthetic peptide IRRRY [21]
Dissociation of Membrane-bound Protein 4.1 by IRRRY—To document that the synthetic peptide IRRRY can selectively dissociate protein 4.1 from band 3 without affecting protein 4.1-glycophorin C interaction, pH 11 inside-out vesicles (IOVs) and T-pH 11 IOVs were first reconstituted with 125I-protein 4.1 and subsequently incubated with increasing concentrations of the peptide, and the release of bound protein 4.1 was monitored (Fig. 1). 194 g of protein 4.1/mg of vesicle proteins bound to band 3 and glycophorin C on pH 11 IOVs, while 98 g of protein 4.1/mg of vesicle proteins bound to glycophorin C on T-pH 11 IOVs
Summary
Protein 4.1 is an important structural component of the erythrocyte membrane. In contrast to our detailed understanding of the role of protein 4.1 in regulating membrane mechanical properties through modulation of spectrin-actin interaction, very little is known regarding the functional implications of protein 4.1 interaction with band 3. We explored the potential role of protein 4.1-band 3 interaction in modulating membrane mechanical properties by studying the functional consequences of specific dissociation of band 3-protein 4.1 interaction using the synthetic peptide IRRRY [21]. The observed alterations in membrane properties appear to result from increased band 3-ankyrin interaction following dissociation of protein 4.1 from band 3 These studies have enabled us to identify an important functional role for band 3-protein 4.1 interaction in modulating erythrocyte membrane properties
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