Radiation-Induced Structural Changes in Human Erythrocyte Membrane Proteins Revealed by Sodium Dodecyl Sulfate/Polyacrylamide Gel Electrophoresis

The effect of X irradiation on the major proteins of human erythrocyte membranes was investigated with respect to a difference in radiosensitivity. The electrophoretic patterns on sodium dodecyl sulfate/polyacrylamide gels revealed that, among seven major proteins, band 1 and 2 proteins, both called spectrin, preferentially disappeared on the gels following X irradiation (100-400 Gy). Spectrin was at least partly transformed into mutually cross-linked aggregates which did not enter the polyacrylamide gels. The most significant effect of the action of X rays was the radiolytic fragmentation of spectrin to short polypeptide pieces having smaller molecular weights than the normal spectrin monomers. These effects of X irradiation could also be detected with purified spectrin molecules. The other major protein bands, 3 to 7, did not diminish to a notable extent. It was also observed that X rays induce changes in the shape of isolated ghosts with a dose-response relationship similar to that for the loss of bands 1 and 2 on the gels. It is suggested that the shape changes of ghosts might be the consequence of radiation-induced structural alterations of spectrin.