Title

Analysis of the mobilities of band 3 populations associated with ankyrin protein and junctional complexes in intact murine erythrocytes.

Document Type

Article

Publication Date

2-3-2012

Keywords

Animals, Anion Exchange Protein 1, Erythrocyte, Ankyrins, Calmodulin-Binding Proteins, Erythrocyte Membrane, Humans, Mice, Mice, Mutant Strains, Protein Binding

JAX Source

J Biol Chem 2012 Feb 3; 287(6):4129-38.

PMID

22147703

Abstract

Current models of the erythrocyte membrane depict three populations of band 3: (i) a population tethered to spectrin via ankyrin, (ii) a fraction attached to the spectrin-actin junctional complex via adducin, and (iii) a freely diffusing population. Because many studies of band 3 diffusion also distinguish three populations of the polypeptide, it has been speculated that the three populations envisioned in membrane models correspond to the three fractions observed in diffusion analyses. To test this hypothesis, we characterized band 3 diffusion by single-particle tracking in wild-type and ankyrin- and adducin-deficient erythrocytes. We report that ∼40% of total band 3 in wild-type murine erythrocytes is attached to ankyrin, whereas ∼33% is immobilized by adducin, and ∼27% is not attached to any cytoskeletal anchor. More detailed analyses reveal that mobilities of individual ankyrin- and adducin-tethered band 3 molecules are heterogeneous, varying by nearly 2 orders of magnitude and that there is considerable overlap in diffusion coefficients for adducin and ankyrin-tethered populations. Taken together, the data suggest that although the ankyrin- and adducin-immobilized band 3 can be monitored separately, significant heterogeneity still exists within each population, suggesting that structural and compositional properties likely vary considerably within each band 3 complex.