2C1M

Nup50:importin-alpha complex

Summary for 2C1M

• Entry DOI: 10.2210/pdb2c1m/pdb
• Related: 1EJL 1EJY 1IAL 1IQ1 1PJM 1PJN 1Q1S 1Q1T 1Y2A
• Descriptor: IMPORTIN-ALPHA2 SUBUNIT, NUCLEOPORIN 50 KDA (3 entities in total)
• Functional Keywords: protein transport/membrane protein, nuclear transport-complex, importin-alpha, nucleoporin nup50, nuclear transport-complex nup50, nuclear protein, protein transport, protein transport-membrane protein complex
• Biological source: MUS MUSCULUS (MOUSE); More
• Cellular location: Cytoplasm (By similarity): P52293; Nucleus, nuclear pore complex: Q9JIH2
• Total number of polymer chains: 2
• Total formula weight: 51424.82

Authors

Matsuura, Y.,Stewart, M. (deposition date: 2005-09-16, release date: 2005-11-23, Last modification date: 2023-12-13)

Primary citation

Matsuura, Y.,Stewart, M.
Nup50/Npap60 Function in Nuclear Protein Import Complex Disassembly and Importin Recycling.
Embo J., 24:3681-, 2005

PubMed Abstract: Nuclear import of proteins containing classical nuclear localization signals (NLS) is mediated by the importin-alpha:beta complex that binds cargo in the cytoplasm and facilitates its passage through nuclear pores, after which nuclear RanGTP dissociates the import complex and the importins are recycled. In vertebrates, import is stimulated by nucleoporin Nup50, which has been proposed to accompany the import complex through nuclear pores. However, we show here that the Nup50 N-terminal domain actively displaces NLSs from importin-alpha, which would be more consistent with Nup50 functioning to coordinate import complex disassembly and importin recycling. The crystal structure of the importin-alpha:Nup50 complex shows that Nup50 binds at two sites on importin-alpha. One site overlaps the secondary NLS-binding site, whereas the second extends along the importin-alpha C-terminus. Mutagenesis indicates that interaction at both sites is required for Nup50 to displace NLSs. The Cse1p:Kap60p:RanGTP complex structure suggests how Nup50 is then displaced on formation of the importin-alpha export complex. These results provide a rationale for understanding the series of interactions that orchestrate the terminal steps of nuclear protein import.

PubMed: 16222336
DOI: 10.1038/SJ.EMBOJ.7600843

Experimental method

X-RAY DIFFRACTION (2.2 Å)