Proteins selectively released from water-extracted human erythrocyte membranes upon citraconylation or maleylation. Electrophoretic analysis and chromatographic fractionation

Abstract

1. Citraconylation or maleylation (carboxylation) of water-extracted human erythrocyte membranes (membrane residue) solubilized up to 20% (w/w) of the membrane residue protein, but less than 2% of the phospholipids. Amino acid analysis and polyacrylamide gel electrophoresis in the presence of dodecylsulfate showed that the solubilization was selective. 2. Polyacrylamide gel electrophoresis in the absence of detergent separated the solubilized acylated proteins into four well-separated major zones and two or three minor zones. Two of the major zones contained proteins of high molecular weight (spectrin components) and the other two contained components of intermediate molecular weight. 3. The solubilized components of intermediate molecular weight could be partially purified by hydroxyapatite chromatography. 4. Upon incubation at pH 5 and 36 degrees C of the unfractionated proteins solubilized by citraconylation some components became specifically degraded or dissociated into subunits.