title: Crystal structure of the nuclear Ras-related protein Ran in its GDP-bound form.
abstract: The Ran proteins constitute a distinct branch of the superfamily of Ras-related GTP-binding proteins which function as molecular switches cycling between GTP-bound 'on' and GDP-bound 'off' states. Ran is located predominantly in the nucleus of eukaryotic cells and is involved in the nuclear import of proteins as well as in control of DNA synthesis and of cell-cycle progression. We report here the crystal structure at 2.3 A resolution of human Ran (Mr 24K) complexed with GDP and Mg2+. This structure reveals a similarity with the Ras core (G-domain) but with significant variations in regions involved in GDP and Mg2+ coordination (switch I and switch II regions in Ras), suggesting that there could be major conformational changes upon GTP binding. In addition to the G-domain, an extended chain and an alpha-helix were identified at the carboxy terminus. The amino-terminal (amino-acid residues MAAQGEP) stretch and the acidic tail (DEDDDL) appear to be flexible in the crystal structure.
authors.affiliation: Max-Planck-Institut für molekulare Physiologie, Abteilung Strukturelle Biologie, Dortmund, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Scheffzek
authors.forename: C
authors.initials: C
authors.lastname: Klebe
authors.forename: K
authors.initials: K
authors.lastname: Fritz-Wolf
authors.forename: W
authors.initials: W
authors.lastname: Kabsch
authors.forename: A
authors.initials: A
authors.lastname: Wittinghofer
mesh_terms: D000595:Amino Acid Sequence; D003196:Computer Graphics; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D019204:GTP-Binding Proteins / Q000737:chemistry*; D006153:Guanosine Diphosphate / Q000737:chemistry*; D006801:Humans; D008274:Magnesium / Q000737:chemistry; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D016415:Sequence Alignment; D020931:ran GTP-Binding Protein
chemical_list: D009687:Nuclear Proteins; D011994:Recombinant Proteins; D006153:Guanosine Diphosphate; D019204:GTP-Binding Proteins; D020931:ran GTP-Binding Protein; D008274:Magnesium