Reversibility of the effects of magnesium depletion. (A) Membrane fragmentation profiles of (1) ghosts prepared in the presence of 2 mM MgCl2; (2) ghosts prepared in the absence of MgCl2; (3) TM-depleted ghosts after addition of purified erythroid TM; and (4) TM-depleted ghosts after addition of a membrane extract containing TM. Note the partial restoration of membrane stability by purified erythrocyte TM and almost complete restoration when the extract was added. (B) Rebinding of erythroid TM to membrane preparations shown in panel A documented by immunoblotting with anti-TM antibody. (C) Membrane stability of ghosts prepared (1) in the presence of MgCl2; (2) in the absence of MgCl2; and (3) after addition of purified muscle TM, showing that this fails to increase membrane stability. (D) Failure of rebinding of muscle TM to membrane preparations shown in panel C documented by immunoblotting with anti-TM antibody. (Lane 4) Purified muscle TM used for membrane reconstitution.
