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Figure 3.
Fig. 3. Structure of Kap95p–RanGDP complex. (a) Two views
of the Kap95p–RanGDP structure, related by a 90° rotation
around the x-axis. Kap95p is shown in cyan, Ran is shown in
pink, and the basic patch region is highlighted in red. (b)
Superposition of free RanGDP (PDB ID 1BYU^18) and RanGDP in
complex with Kap95p. Switch regions are highlighted in light
blue (switch I), magenta (switch II), and pink (basic patch) for
free RanGDP, and in blue (switch I), purple (switch II), and red
(basic patch) for RanGDP in complex with Kap95p. (c)
Superposition of RanGDP and RanGTP (PDB ID 2BKU^5) in complex
with Kap95p; RanGDP switch regions are blue (switch I), purple
(switch II), and red (basic patch); RanGTP switch regions are
light blue (switch I), magenta (switch II), and pink (basic
patch). (d) Structural comparison of Kap95p–RanGTP,^5
Kap95p–RanGDP, and HEAT repeats 1–11 of importin-β in
complex with PTHrP.^27 The schematic diagrams summarize the
conformational differences. The conformational shift in the
basic patch region of Ran exposes a part of Kap95p HEAT repeat 7
that is important for binding NLS-containing importin-β cargoes
including PTHrP,^27 SREBP-2,^28 and importin α.^12 It is
unlikely that the observed structural differences between
Kap95p–RanGTP and Kap95p–RanGDP are the result of crystal
packing, because they both possessed an equivalent arrangement
of the protein molecules.
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