Crystal structure of human Band3 (anion exchanger)

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Human AE1 is a 110kDa glycoprotein. It is built from two domains, a cytosolic N-terminal domain (residues 1-360) and an integral membrane domain (residues 361-911). Anion exchange is catalysed by the C-terminal domain. However, only the crystal structure of the cytosolic N-terminal domain, important as an anchoring point for other proteins including the scaffolding protein ankyrin and deoxy-hemoglobin, has been determined. As such the details of the topology, the substrate recognition, and the anion-transport mechanism of this fundamental protein remain unclear. We analyzed the crystal structure at 3.4 angstrom resolution of the membrane domain of human AE1 locked in an outward open conformation by a covalently bound H2DIDS-inhibitor in complex with a Fab fragment from a monoclonal antibody. We also need the structure of an inward-facing open conformation or an outward-facing open conformation at higher resolution to understand the fully anion exchange mechanism of AE1.