title: Solution structure of the cytoplasmic domain of erythrocyte membrane band 3 determined by site-directed spin labeling.
abstract: The cytoplasmic domain of the anion exchange protein (cdb3) serves as a critical organizing center for protein-protein interactions that stabilize the erythrocyte membrane. The structure of the central core of cdb3, determined by X-ray crystallography from crystals grown at pH 4.8, revealed a compact dimer for residues 55-356 and unresolved N- and C-termini on each monomer [Zhang et al. (2000) Blood 96, 2925-2933]. Given that previous studies had suggested a highly asymmetric structure for cdb3 and that pH dependent structural transitions of cdb3 have been reported, the structure of cdb3 in solution at neutral pH was investigated via site-directed spin labeling in combination with conventional electron paramagnetic resonance (EPR) and double electron electron resonance (DEER) spectroscopies. These studies show that the structure of the central compact dimer (residues 55-356) is indistinguishable from the crystal structure determined at pH 4.8. N-Terminal residues 1-54 and C-terminal residues 357-379 are dynamically disordered and show no indications of stable secondary structure. These results establish a structural model for cdb3 in solution at neutral pH which represents an important next step in characterizing structural details of the protein-protein interactions that stabilize the erythrocyte membrane.
authors.affiliation: Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhou
authors.forename: Susan C
authors.initials: SC
authors.lastname: DeSensi
authors.forename: Richard A
authors.initials: RA
authors.lastname: Stein
authors.forename: Suzanne
authors.initials: S
authors.lastname: Brandon
authors.forename: Mrinalini
authors.initials: M
authors.lastname: Dixit
authors.forename: Erin J
authors.initials: EJ
authors.lastname: McArdle
authors.forename: Eric M
authors.initials: EM
authors.lastname: Warren
authors.forename: Heather K
authors.initials: HK
authors.lastname: Kroh
authors.forename: Likai
authors.initials: L
authors.lastname: Song
authors.forename: Charles E
authors.initials: CE
authors.lastname: Cobb
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Hustedt
authors.forename: Albert H
authors.initials: AH
authors.lastname: Beth
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry*; D003593:Cytoplasm / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005453:Fluorescence; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013113:Spin Labels; D014364:Tryptophan / Q000737:chemistry
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D011994:Recombinant Proteins; D013113:Spin Labels; D014364:Tryptophan