title: Rotational diffusion of band 3 in the red cell membrane: measurements using triplet probes.
abstract: Rotational diffusion of band 3 in the human erythrocyte membrane has been investigated using the technique of flash photolysis. Membranes are labeled with the triplet probe eosin isothiocyanate; most of the label is found to be associated with band 3. Rotation is measured by observing the decay of dichroism of flash-induced absorbance changes arising from the eosin probe. The results indicate that band 3 rotates about an axis normal to the plane of the membrane with a diffusion coefficient in the order of 1,000 sec-1. Removal of spectrin has no observable effect on the rotation of band 3 at pH 7.6. Essentially similar results are obtained with a different probe, iodoacetamidoeosin. Both eosin derivatives are strong inhibitors of anion transport. Illumination of eosin-labeled ghosts causes a rapid loss of acetylcholinesterase activity but this can be prevented by prior displacement of oxygen in the sample by argon.
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood; D000838:Anions; D001693:Biological Transport, Active; D004058:Diffusion; D004801:Eosine Yellowish-(YS); D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000097:blood*; D010782:Photolysis; D013049:Spectrin / Q000378:metabolism
chemical_list: D000838:Anions; D008565:Membrane Proteins; D013049:Spectrin; D000110:Acetylcholinesterase; D004801:Eosine Yellowish-(YS)