Effect of magnesium depletion on membrane stability and on membrane protein retention. (A) Membrane stability, expressed as the rate of decline in ektacytometric deformability index (DI), increases (decay curve shifted toward right) with increasing concentrations of MgCl₂ maintained during preparation of the ghosts. (B) Retention of TM by ghosts examined in panel A. (C) Components of junction complexes of ghosts prepared in the absence or in the presence of 2 mM MgCl₂. The panels show immunoblots after SDS-PAGE of total protein from ghosts, prepared with and without MgCl₂ as indicated, probed with antibodies against 4.1R, adducin, protein 4.9, capZ, tropomodulin, and TM.