Degree of cytoskeletal attachment of nonliganded and liganded GPA in reticulocytes and mature red cells. (A) FTSC-labeled GPA in reticulocytes from FVA cell culture; (B) FTSC-labeled, Ter119-liganded GPA in reticulocytes from FVA cell culture; (C) PE-Ter119–liganded GPA in reticulocytes from FVA cell culture; (D) FTSC-labeled GPA in mature red cells; and (E) PE-Ter119–liganded GPA in mature red cells. Ligand binding increased γ_GPA in both reticulocytes and mature red cells.