Changes of the asymmetrical particle distribution in erythrocyte membranes

Particle counts in freeze-fractured human erythrocytes revealed changes in the asymmetry coefficients of the particle distribution between the two membrane fracture faces after several pretreatments caused by significant differences in the particle densities on both fracture faces. In comparison with the high asymmetry of the particle distribution present in serum-incubated erythrocytes the asymmetry is lowered already in NaCl-incubated erythrocytes and to a greater extent in MgCl2- or CaCl2-incubated erythrocytes by the decrease of the particle density on the P-face and the simultaneous increase of the particle density on the E-face. This clearly shows that a redistribution of the intramembraneous particles between the two membrane fracture faces is possible. The asymmetry-lowering effect of MgCl2 is not present after combined MgCl2-glycerol- or MgCl2-glutaraldehyde-treatment. It is suggested that the variable strong interaction of the transmembraneous proteins, involved in the particle formation, with the extracellular membrane half influence the particle distribution between the two fracture faces in native human erythrocytes.