2bku | pdb_00002bku
Kap95p:RanGTP complex
Structural highlights
Function[IMB1_YEAST] Required for nuclear protein import and mediates docking of import substrate to distinct nucleoporins. Serves a receptor for nuclear localization signals. Mediates the nuclear import of histones H2A and H2B.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedNuclear 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. 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[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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