Solubilisation of human erythrocyte band 4.1 protein in the non-ionic detergent Tween 20

Extraction of spectrin-depleted erythrocyte membranes with the non-ionic detergent Tween 20, in a 0.1 M glycine-NaOH buffer (pH 9.8) leads to the solubilization of band 4.1 and the sialoglycoproteins. The comigration of band 4.1 with the sialoglycoproteins in gel filtration and detergent-free electrophoresis indicated that these proteins may be associated as complexes of high molecular weight. Although treatment of intact membranes with Tween 20 under the same conditions does not lead to direct solubilization of proteins, severe disruption of the membranes was observed under phase contrast microscopy. Suspension of the treated membranes in 5 mM phosphate buffer (pH 8.0) leads to the solubilization of band 4.1, spectrin, actin and the sialoglycoproteins. High molecular weight complexes of band 4.1 and the sialoglycoproteins were isolated from these extracts, suggesting a possible interaction between band 4.1 and sialoglycoproteins which may be important for linking the cytoskeleton to the membrane.