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Figure 1.
Fig. 1. Structure of Impβ in complex with IBB[SPN1]. (a)
Overall structure of Impβ/IBB[SPN1], with a view into the
C-terminal cavity. The IBB domain of SPN1 is depicted in red,
the N-terminal arch of Impβ, which is not involved in the
interaction is shown in blue, the C-terminal arch, binding to
IBB[SPN1], is shown in green. (b) Structure rotated by 90°,
with view from the C terminus of Impβ; colouring as in (a).
HEAT 13B, illustrated in yellow, is inclined toward IBB[SPN1].
(c) and (d) Detailed view into interactions between
Impβ_127–876 and IBB[SPN1]; colouring as in (a). Side chains
involved in binding are depicted as ball and stick
presentations. (c) View from the top of the C-terminal arch of
Impβ. (d) View from the bottom of the C-terminal arch. (e) and
(f) Electron density presentations of the environments of two
arginines of IBB[SPN1], which interact with Impβ_127–876.
Dotted lines mark hydrogen bonds. (e) The hydrogen bond network
with Arg43 of IBB[SPN1] as center involves Cys585, Asp627 and
Met630 of Impβ; in close vicinity is Gln40 of IBB[SPN1],
forming an intramolecular hydrogen bond. (f) Arg63 not only is
bound to Gly820 with a single bond and to Asp824 via a bidentite
hydrogen bond, but also coordinates a water molecule that is
involved in the hydration shell of Impβ.
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