1qgr
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STRUCTURE OF IMPORTIN BETA BOUND TO THE IBB DOMAIN OF IMPORTIN ALPHA (II CRYSTAL FORM, GROWN AT LOW PH)
OverviewOverview
Cytosolic proteins bearing a classical nuclear localization signal enter the nucleus bound to a heterodimer of importin-alpha and importin-beta (also called karyopherin-alpha and -beta). The formation of this heterodimer involves the importin-beta-binding (IBB) domain of importin-alpha, a highly basic amino-terminal region of roughly 40 amino-acid residues. Here we report the crystal structure of human importin-beta bound to the IBB domain of importin-alpha, determined at 2.5 A and 2.3 A resolution in two crystal forms. Importin-beta consists of 19 tandemly repeated HEAT motifs and wraps intimately around the IBB domain. The association involves two separate regions of importin-beta, recognizing structurally distinct parts of the IBB domain: an amino-terminal extended moiety and a carboxy-terminal helix. The structure indicates that significant conformational changes occur when importin-beta binds or releases the IBB domain domain and suggests how dissociation of the importin-alpha/beta heterodimer may be achieved upon nuclear entry.
About this StructureAbout this Structure
1QGR is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Structure of importin-beta bound to the IBB domain of importin-alpha., Cingolani G, Petosa C, Weis K, Muller CW, Nature. 1999 May 20;399(6733):221-9. PMID:10353244
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