1xk5

Crystal structure of the m3G-cap-binding domain of snurportin1 in complex with a m3GpppG-cap dinucleotideCrystal structure of the m3G-cap-binding domain of snurportin1 in complex with a m3GpppG-cap dinucleotide

Structural highlights 1xk5 is a 1 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SPN1_HUMAN] Functions as an U snRNP-specific nuclear import adapter. Involved in the trimethylguanosine (m3G)-cap-dependent nuclear import of U snRNPs. Binds specifically to the terminal m3G-cap U snRNAs. 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 PubMed In higher eukaryotes the biogenesis of spliceosomal UsnRNPs involves a nucleocytoplasmic shuttling cycle. After the m7G-cap-dependent export of the snRNAs U1, U2, U4 and U5 to the cytoplasm, each of these snRNAs associates with seven Sm proteins. Subsequently, the m7G-cap is hypermethylated to the 2,2,7-trimethylguanosine (m3G)-cap. The import adaptor snurportin1 recognises the m3G-cap and facilitates the nuclear import of the UsnRNPs by binding to importin-beta. Here we report the crystal structure of the m3G-cap-binding domain of snurportin1 with bound m3GpppG at 2.4 A resolution, revealing a structural similarity to the mRNA-guanyly-transferase. Snurportin1 binds both the hypermethylated cap and the first nucleotide of the RNA in a stacked conformation. This binding mode differs significantly from that of the m7G-cap-binding proteins Cap-binding protein 20 (CBP20), eukaryotic initiation factor 4E (eIF4E) and viral protein 39 (VP39). The specificity of the m3G-cap recognition by snurportin1 was evaluated by fluorescence spectroscopy, demonstrating the importance of a highly solvent exposed tryptophan for the discrimination of m7G-capped RNAs. The critical role of this tryptophan and as well of a tryptophan continuing the RNA base stack was confirmed by nuclear import assays and cap-binding activity tests using several snurportin1 mutants. Structural basis for m3G-cap-mediated nuclear import of spliceosomal UsnRNPs by snurportin1.,Strasser A, Dickmanns A, Luhrmann R, Ficner R EMBO J. 2005 Jul 6;24(13):2235-43. Epub 2005 May 26. PMID:15920472 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

spinqualitylabelsall models 1xk5, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image