Intramembrane particle aggregation in erythrocyte membranes and band 3-lipid recombinants.

The low pH-induced aggregation of intramembrane particles in human erythrocyte membranes was studied in native membranes and in a reconstituted model system. A significant difference in such aggregation was found when samples of freshly prepared ghosts were compared to ghosts receiving pretreatments that removed most of spectrin-actin from underneath the membrane. All conditions effective in aggregating particles are equally effective in precipitating extracted mixtures of spectrin and actin. In Band 3-lipid recombinants, the pH-induced aggregation of particles was duplicated only in samples containing spectrin-actin that equilibrated with these recombinants in sucrose gradients. Therefore, it was proposed that spectrin-actin components, through their associations with the underlying intramembrane particles, could impede particle lateral mobility and also determine particle redistribution in erythrocyte membrane.