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2bku
From Proteopedia
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KAP95P:RANGTP COMPLEX
Overview
Nuclear protein import is mediated mainly by the transport factor, importin-beta that binds cytoplasmic cargo, most often via the, importin-alpha adaptor, and then transports it through nuclear pore, complexes. This active transport is driven by disassembly of the import, complex by nuclear RanGTP. The switch I and II loops of Ran change, conformation with nucleotide state, and regulate its interactions with, nuclear trafficking components. Importin-beta consists of 19 HEAT repeats, that are based on a pair of antiparallel alpha-helices (referred to as the, A- and B-helices). The HEAT repeats stack to yield two C-shaped arches, linked together to form a helicoidal molecule that has considerable, conformational flexibility. Here we present the structure of full-length, yeast importin-beta (Kap95p or karyopherin-beta) complexed with RanGTP, which provides a basis for understanding the crucial cargo-release step of, nuclear import. We identify a key interaction site where the RanGTP switch, I loop binds to the carboxy-terminal arch of Kap95p. This interaction, produces a change in helicoidal pitch that locks Kap95p in a conformation, that cannot bind importin-alpha or cargo. We suggest an allosteric, mechanism for nuclear import complex disassembly by RanGTP.
About this Structure
2BKU is a Protein complex structure of sequences from Canis lupus familiaris and Saccharomyces cerevisiae with MG and GTP as ligands. The following page contains interesting information on the relation of 2BKU with [Importins]. Structure known Active Site: AC1. Full crystallographic information is available from OCA.
Reference
Structural basis for nuclear import complex dissociation by RanGTP., Lee SJ, Matsuura Y, Liu SM, Stewart M, Nature. 2005 Jun 2;435(7042):693-6. Epub 2005 May 1. PMID:15864302
Page seeded by OCA on Mon Nov 5 17:41:48 2007
