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

Abstract

Changes in pH significantly affect the morphology and physical properties of red cell membranes. The molecular basis for these phenomena were studied by characterizing the pattern of protein disulfide cross-linkages formed spontaneously in ghosts exposed to acid pH or elevated temperature (37.degree. C). Protein aggregation was analyzed by 2-dimensional polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Incubation of ghosts at pH 4.0 to 5.5 (0-4.degree. C) yielded: complexes of spectrin and band 3; complexes of actin and band 3; band 3 complexes, i.e., dimer and trimer; and 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 the aggregation of intramembrane particles including band 3 and more intimate contact between spectrin-actin meshwork and band 3.