Myotonic dystrophy: Fragility of band 3 membrane protein upon resealing of erythrocyte ghosts and the normality of ATPase activity, sialic acid content, and spectrin extractability of ghosts

Abstract Since a number of recent reports (2, 14) have shown that myotonic dystrophy (MyD) might be an inherited disorder of cell membranes, we studied erythrocytes of 10 patients with MyD to investigate the membrane abnormality. In the osmotical aspect, the relative hemolysis of erythrocytes in patients with MyD in a solution of 75 m m NaCl displayed almost half the value of the normal level. Our experiments using electrophoresis demonstrated that a main polypeptide of membrane, band 3 (by the nomenclature of Fairbanks et al. (15)), in patients with MyD was very fragile in the process of erythrocyte ghosts resealing in the isotonic medium. No significant differences were observed in membrane-bound Ca 2+ -ATPase activities, sialic acid contents, and spectrin extractability assessed by SDS-polyacrylamide gel electrophoresis between normal and MyD. It is suggested that abnormality of MyD erythrocytes may be localized to the surface membrane, especially around band 3.