Studies on the fragmentation of erythrocyte ghost membrane with p-chloromercuribenzoate in the micromolar range.

The effects of nonsaturating amounts (5-60 nmol/mg membrane protein) of p-chloromercuribenzoate on the stability of unsealed erythrocyte ghosts were studied by turbidimetric measurements and direct observation by phase contrast microscopy. The organic mercurial provokes drastic disorganization of the membrane involving vesicle formation by inter- and externalization of the bilayer. These effects are not associated with a release in solution of membrane proteins which was shown in previous studies to occur at higher p-chloromercuribenzoate concentration. Attempts have been made to identify the proteins involved in this phenomenon by the use of nonsaturating amounts of radioactively-labelled p-chloromercuribenzoate. Actin and band 3 protein which are the first to be labelled, represent plausible candidates as sensitive targets for the disrupting organic mercurial. Stroma obtained from spherocytes did not show significant differences with normocytes in their stability with regard to p-chloromercuribenzoate. Other reagents including N-ethylmaleimide, diamide and DNAase I were also studied. The results suggest strongly that the integrity of the sulfhydryl groups of actin, as well as those of band 3 protein, is essential for the stability of the erythrocyte membrane.