title: Crystallization and preliminary X-ray crystallographic study of the Ras-GTPase-activating domain of human p120GAP.
abstract: Ras-GTPase-activating proteins (Ras-GAPs) are important regulators of the biological activity of Ras within the framework of intracellular communication where GTP-bound Ras (Ras:GTP) is a key signal transducing molecule (Trahey and McCormick, Science 238:542-545, 1987; Boguski and McCormick, Nature 366:643-654, 1993). By accelerating Ras-mediated GTP hydrolysis, Ras-GAPs provide an efficient means to reset the Ras-GTPase cycle to the GDP-bound 'OFF'-state and terminate the Ras-mediated signal. Here we report the crystallization of the GTPase-activating domain of the human p120GAP. The crystals-belong to the orthorhombic space group symmetry P2(1)2(1)2(1) with unit cell dimensions of a = 42.2 A, b = 55.6 A, c = 142.2 A, alpha = beta = gamma = 90 degrees. Assuming a Matthews parameter of 2.2 A3/Da, there is one molecule per asymmetric unit. Applying micro-seeding techniques, we grew large single crystals that could not be obtained by other routine methods for crystal improvement. They diffracted to a resolution of approximately 3 A using X-rays from a rotating anode generator and to better than 1.8 A in a synchrotron beam. Chemical cross-linking led to reduction of the maximum resolution but to significantly increased stability against mechanical and heavy atom stress.
authors.affiliation: Max-Planck-Institut für molekulare Physiologie, Abt. Strukturelle Biologie, Dortmund, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Scheffzek
authors.forename: A
authors.initials: A
authors.lastname: Lautwein
authors.forename: A
authors.initials: A
authors.lastname: Scherer
authors.forename: S
authors.initials: S
authors.lastname: Franken
authors.forename: A
authors.initials: A
authors.lastname: Wittinghofer
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D020558:GTP Phosphohydrolases / Q000737:chemistry*; D020690:GTPase-Activating Proteins; D006801:Humans; D011506:Proteins / Q000737:chemistry*; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D011506:Proteins; D020703:ras GTPase-Activating Proteins; D020558:GTP Phosphohydrolases