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From Proteopedia
Crystal Structure of Importin 13 - RanGTP - eIF1A complex
Structural highlights
FunctionRAN_HUMAN GTP-binding protein involved in nucleocytoplasmic transport. Required for the import of protein into the nucleus and also for RNA export. Involved in chromatin condensation and control of cell cycle (By similarity). The complex with BIRC5/ survivin plays a role in mitotic spindle formation by serving as a physical scaffold to help deliver the RAN effector molecule TPX2 to microtubules. Acts as a negative regulator of the kinase activity of VRK1 and VRK2.[1] [2] [3] [4] Enhances AR-mediated transactivation. Transactivation decreases as the poly-Gln length within AR increases.[5] [6] [7] [8] Publication Abstract from PubMedImportin13 (Imp13) is a bidirectional karyopherin that can mediate both import and export of cargoes. Imp13 recognizes several import cargoes, which include the exon junction complex components Mago-Y14 and the E2 SUMO-conjugating enzyme Ubc9, and one known export cargo, the translation initiation factor 1A (eIF1A). To understand how Imp13 can perform double duty, we determined the 3.6-A crystal structure of Imp13 in complex with RanGTP and with eIF1A. eIF1A binds at the inner surface of the Imp13 C-terminal arch adjacent and concomitantly to RanGTP illustrating how eIF1A can be exported by Imp13. Moreover, the 3.0-A structure of Imp13 in its unbound state reveals the existence of an open conformation in the cytoplasm that explains export cargo release and completes the export branch of the Imp13 pathway. Finally, we demonstrate that Imp13 is able to bind and export eIF1A in vivo and that its function is essential. Structural basis for the nuclear export activity of Importin13.,Grunwald M, Lazzaretti D, Bono F EMBO J. 2013 Mar 20;32(6):899-913. doi: 10.1038/emboj.2013.29. Epub 2013 Feb 22. PMID:23435562[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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