Rotational diffusion of erythrocyte membrane proteins.
Rotational diffusion of band 3 proteins in human erythrocyte membranes is measured by observing flash-induced transient dichroism of the triplet probe, eosin-maleimide. At physiological temperature, both fast and slowly rotating populations of band 3 are present in the membrane. Rotational motion of band 3 is the same in membranes from young and old erythrocytes and is unchanged when the cholesterol:phospholipid mole ratio is varied from 1.34 to 1.66. Antibodies against glycophorin A immobilize band 3, indicating an association between these two integral membrane proteins. However, glycophorin A has little effect on the rotational motion of the complex, since band 3 rotation in En(a-) membranes (which lack glycophorin A) is similar to that observed in normal membranes. Cleavage of the cytoplasmic segment of band 3 by trypsin produces a considerable enhancement of band 3 rotational mobility. A similar effect is seen following extraction of bands 2.1 and 4.1 by sequential low salt-high salt treatment. It is concluded that up to 40% of band 3 has restricted rotational mobility due to interaction with the erythrocyte cytoskeleton.
D001798:Blood Proteins / Q000032:analysis*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002784:Cholesterol / Q000097:blood; D004910:Erythrocyte Membrane / Q000032:analysis*; D004912:Erythrocytes / Q000032:analysis*; D006021:Glycophorins / Q000032:analysis; D006801:Humans; D008565:Membrane Proteins / Q000097:blood*; D011487:Protein Conformation; D012399:Rotation; D013696:Temperature; D013997:Time Factors
D001798:Blood Proteins; D006021:Glycophorins; D008565:Membrane Proteins; D002784:Cholesterol