THE DISSOCIATION OF PERIPHERAL PROTEINS FROM ERYTHROCYTE-MEMBRANES BROUGHT ABOUT BY PARA-MERCURIBENZENESULFONATE

The organic mercurial p-mercuribenzenesulfonate in 5 mM phosphate buffer (pH 8.0) solubilized ankyrin, bands 4.1 and 4.2, and glyceraldehyde-3-phosphate dehydrogenase from spectrin-depleted erythrocyte membranes. Glyceraldehyde-3-phosphate dehydrogenase was the protein most readily solubilized, being almost completely extracted by 0.5 mM reagent. The solubilization of ankyrin was similar to that of band 4.2, both showing maximal solubilization with 1.0 mM reagent. Band 4.1 was not appreciably solubilized below 2.5 mM p-mercuribenzenesulfonate. N-Ethylmaleimide did not itself solubilize proteins from ghosts or spectrin-depleted vesicles, and pretreatment at low temperature by 4 mM N-ethylmaleimide did not prevent subsequent solubilization by the mercurial. However, pretreatment at 37°C with N-ethylmaleimide inhibited subsequent solubilization of ankyrin and band 4.2 by the mercurial and also resulted in the loss of binding of 1 mol mercurial per mol band 3. These data suggest that release of ankyrin and band 4.2 from the membrane by mercurial is linked to modification of band 3 by the reagent. After incubation of intact erythrocyte membranes with 0.1 M NaCl, treatment with p-mercuribenzenesulfonate selectively solubilized actin from the membranes. The resulting actin-depleted membranes did not vesiculate, but became spherical and lost their biconcave shape. Fragmentation was observed after subsequent removal of spectrin at low ionic strength. © 1990.