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From Proteopedia
CRYSTAL STRUCTURE OF IMPORTIN 13 - UBC9 COMPLEX
Structural highlights
FunctionUBC9_HUMAN Accepts the ubiquitin-like proteins SUMO1, SUMO2, SUMO3 and SUMO4 from the UBLE1A-UBLE1B E1 complex and catalyzes their covalent attachment to other proteins with the help of an E3 ligase such as RANBP2 or CBX4. Can catalyze the formation of poly-SUMO chains. Necessary for sumoylation of FOXL2 and KAT5. Essential for nuclear architecture and chromosome segregation.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedImportin13 (Imp13) is an unusual beta-karyopherin that is able to both import and export cargoes in and out of the nucleus. In the cytoplasm, Imp13 associates with different cargoes such as Mago-Y14 and Ubc9, and facilitates their import into the nucleus where RanGTP binding promotes the release of the cargo. In this study, we present the 2.8 A resolution crystal structure of Imp13 in complex with the SUMO E2-conjugating enzyme, Ubc9. The structure shows an uncommon mode of cargo-karyopherin recognition with Ubc9 binding at the N-terminal portion of Imp13, occupying the entire RanGTP-binding site. Comparison of the Imp13-Ubc9 complex with Imp13-Mago-Y14 shows the remarkable plasticity of Imp13, whose conformation changes from a closed ring to an open superhelix when bound to the two different cargoes. The structure also shows that the binding mode is compatible with the sumoylated states of Ubc9. Indeed, we find that Imp13 is able to bind sumoylated Ubc9 in vitro and suppresses autosumoylation activity in the complex. Structure of Importin13-Ubc9 complex: nuclear import and release of a key regulator of sumoylation.,Grunwald M, Bono F EMBO J. 2010 Dec 7. PMID:21139563[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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