Spontaneous, reversible protein cross-linking in the human erythrocyte membrane. Temperature and pH dependence.

Changes in pH significantly affect the morphology and physical properties of red cell membranes. We have explored the molecular basis for these phenomena by characterizing the pattern of protein disulfide cross-linkages formed spontaneously in ghost exposed to acid pH or elevated temperature (37 degrees C). Protein aggregation was analyzed by two-dimensional polyacrylamide gel electrophoresis in sodium dodecyl sulfate. incubation of ghosts at pH 4.0 to 5.5 (0-4 degrees C) yielded (i) complexes of spectrin and band 3, (ii) complexes of actin and band 3, (iii) band 3 complexes, i.e. dimer and trimer, and (iv) heterogeneous aggregates involving spectrin, band 3, band 4.2, and actin in varying proportions. Aggregation was maximal near the isoelectric points of the major membrane proteins, and appeared to reflect (i) the aggregation of intramembrane particles including band 3 and (ii) more intimate contact between spectrin-actin meshwork and band 3.