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Three‐dimensional map of the dimeric membrane domain of the human erythrocyte anion exchanger, Band 3.
Author(s) -
Wang D.N.,
Sarabia V.E.,
Reithmeier R.A.,
Kühlbrandt W.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06624.x
Subject(s) - band 3 , biology , library science , erythrocyte membrane , biochemistry , computer science , membrane
The electroneutral exchange of chloride and bicarbonate across the human erythrocyte membrane is facilitated by Band 3, a 911 amino acid glycoprotein consisting of a 43 kDa N‐terminal cytosolic domain that binds the cytoskeleton, haemoglobin and glycolytic enzymes and a 52 kDa C‐terminal membrane domain that mediates anion transport. Electron microscopy and three‐dimensional image reconstruction of negatively stained two‐dimensional crystals of the dimeric membrane domain revealed a U‐shaped structure with dimensions of 60 × 110 A, and a thickness of 80 A. The structure is open on the top and at the sides, with the monomers in close contact at the base. The basal domain is 40 A thick and probably spans the lipid bilayer. The upper part of the dimer consists of two elongated protrusions measuring 25 × 80 A in projection, with a thickness of 40 A. The protrusions form the sides of a canyon, enclosing a wide space that narrows down and converges into a depression at the centre of the dimer on the top of the basal domain. This depression may represent the opening to a transport channel located at the dimer interface. Based on the available protein‐chemical data, the two protrusions face the cytosolic side of the membrane and they appear to be dynamic.