title: Inhibition of GTPase activating protein stimulation of Ras-p21 GTPase by the Krev-1 gene product.
abstract: Krev-1 is known to suppress transformation by ras. However, the mechanism of the suppression is unclear. The protein product of Krev-1, Rap1A-p21, is identical to Ras-p21 proteins in the region where interaction with guanosine triphosphatase (GTPase) activating protein (GAP) is believed to occur. Therefore, the ability of GAP to interact with Rap1A-p21 was tested. Rap1A-p21 was not activated by GAP but bound tightly to GAP and was an effective competitive inhibitor of GAP-mediated Ras-GTPase activity. Binding of GAP to Rap1A-p21 was strictly guanosine triphosphate (GTP)-dependent. The ability of Rap1A-p21 to bind tightly to GAP may account for Krev-1 suppression of transformation by ras. This may occur by preventing interaction of GAP with Ras-p21 or with other cellular proteins necessary for GAP-mediated Ras GTPase activity.
authors.affiliation: Max-Planck-Institute für medizinische Forschung, Abteilung Biophysik, Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Frech
authors.forename: J
authors.initials: J
authors.lastname: John
authors.forename: V
authors.initials: V
authors.lastname: Pizon
authors.forename: P
authors.initials: P
authors.lastname: Chardin
authors.forename: A
authors.initials: A
authors.lastname: Tavitian
authors.forename: R
authors.initials: R
authors.lastname: Clark
authors.forename: F
authors.initials: F
authors.lastname: McCormick
authors.forename: A
authors.initials: A
authors.lastname: Wittinghofer
mesh_terms: D001667:Binding, Competitive; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D015689:Oncogene Protein p21(ras) / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000037:antagonists & inhibitors*; D013489:Suppression, Genetic; D020668:rap GTP-Binding Proteins; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D011506:Proteins; D020703:ras GTPase-Activating Proteins; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D015689:Oncogene Protein p21(ras); D020668:rap GTP-Binding Proteins