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Stereo figure showing residues 49–52 and 44–48 for the four subunits of CP49/48 (green) with the closed and open loops of the liganded (yellow) and unliganded (cyan) wild-type streptavidins. Biotin is included as described in Fig. 2 ▶ except that the Asn49 hydrogen bond is not present in CP49/48.
