title: Analysis of the mobilities of band 3 populations associated with ankyrin protein and junctional complexes in intact murine erythrocytes.
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.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Gayani C
authors.initials: GC
authors.lastname: Kodippili
authors.forename: Jeff
authors.initials: J
authors.lastname: Spector
authors.forename: Jacob
authors.initials: J
authors.lastname: Hale
authors.forename: Katie
authors.initials: K
authors.lastname: Giger
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hughes
authors.forename: Kelly M
authors.initials: KM
authors.lastname: McNagny
authors.forename: Connie
authors.initials: C
authors.lastname: Birkenmeier
authors.forename: Luanne
authors.initials: L
authors.lastname: Peters
authors.forename: Ken
authors.initials: K
authors.lastname: Ritchie
authors.forename: Philip S
authors.initials: PS
authors.lastname: Low
mesh_terms: D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics / Q000378:metabolism*; D017487:Ankyrins / Q000235:genetics / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D011485:Protein Binding / Q000502:physiology; D000099291:Adducins
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D017487:Ankyrins; D002148:Calmodulin-Binding Proteins; D000099291:Adducins