“…Abundant evidence implicates the RBC membrane skeleton in controlling band 3 lateral mobility. Disruption of spectrin-ankyrin and ankyrin-band 3 linkages causes band 3 mobility to increase (21)(22)(23)(24), as does treatment with proteases to remove the cytoplasmic domain of band 3 (25,26) or treatment with ATP or 2,3-DPG (27) at levels that are sufficient to destabilize isolated RBC membrane skeletons (28) Band 3 rotational mobility has been studied in normal RBC ghosts (26,(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44), abnormal RBC ghosts (45,46), and intact RBCs (19,31,37).2 Rapidly rotating, slowly rotating, and rotationally immobile forms of band 3 appear to coexist in the membrane. At 37°C in normal RBC membranes, 20-25% of band 3 molecules rotate with correlation times (r) < 250 Ms, 50-75% rotate with r 1-3 ms, and 5-25% are rotationally immobile on the time scale of the experiment (19,37,40 About half of the rapidly rotating band 3 molecules may rotate with correlation times of 25-30 ,ts; this population could represent band 3 dimers rotating free of constraints other than the viscosity of the lipid bilayer (37).…”