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Figure 5.
Figure 5. Anion-binding region of CLC-ec1 in Br^− and
SeCN^−. Crystals of (a) and (b) wild-type CLC-ec1 and (c) and
(d) E148A mutant were grown in (a) and (c) Br^− or (b)and (d)
SeCN^−, and structures were determined to 3.1–3.4 Å.
Shown here is the anion-binding region, with anion-coordinating
side-chains Glu(Ala)148, Ser107, and Tyr445 indicated. Anomalous
difference maps for Br^− (green) or SeCN^− (red) were
calculated and contoured at 4 σ. For E148A in Br^−-the three
anion-binding sites (external, central, and inner) are shown by
anomalous density; in this dataset, inner-site binding is weak.
Not shown here are additional loci of anomalous Se density at
the aqueous surfaces of the transporter; these are probably of
no functional significance, since Br^− is never seen here. PDB
accession number for wild-type in SeCN^− 2H2P; for E148A in
SeCN^− 2H2S.
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