Proteolysis of band 3 is enhanced by anti-Rho(D) binding to the red cell membrane.

Surface radioiodinated human red cells were incubated with IgG fractions and the radioelectrophoretic profile of the ghost membranes determined. The patterns of RhO(D)-negative membranes exposed to anti-RhO(D) IgG and RhO(D)-positive membranes exposed to non-immune IgG fractions remained intact. Membranes of RhO(D)-positive membranes following incubation with anti-RhO(D) IgG showed a sharp reduction in the quantity of intact band 3, the main glycoprotein of the red cell membrane. This process was significantly abrogated in the presence of protease inhibitors. The results suggest a possible role for IgG binding in promoting the generation of band 3-derived fragments described by others as normal constituents of isolated ghosts.