title: Nitric oxide-stimulated guanine nucleotide exchange on p21ras.
abstract: The protooncogene p21ras, a monomeric G protein family member, plays a critical role in converting extracellular signals into intracellular biochemical events. Here, we report that nitric oxide (NO) activates p21ras in human T cells as evidenced by an increase in GTP-bound p21ras. In vitro studies using pure recombinant p21ras demonstrate that the activation is direct and reversible. Circular dichroism analysis reveals that NO induces a profound conformational change in p21ras in association with GDP/GTP exchange. The mechanism of activation is due to S-nitrosylation of a critical cysteine residue which stimulates guanine nucleotide exchange. Furthermore, we demonstrate that p21ras is essential for NO-induced downstream signaling, such as NF-kappa B activation, and that endogenous NO can activate p21ras in the same cell. These studies identify p21ras as a target of the same cell. These studies identify p21ras as a target of NO in T cells and suggest that NO activates p21ras by an action which mimics that of guanine nucleotide exchange factors.
authors.affiliation: Department of Pharmacology, Cornell University Medical College, New York, New York 10021, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Lander
authors.forename: J S
authors.initials: JS
authors.lastname: Ogiste
authors.forename: S F
authors.initials: SF
authors.lastname: Pearce
authors.forename: R
authors.initials: R
authors.lastname: Levi
authors.forename: A
authors.initials: A
authors.lastname: Novogrodsky
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D002248:Carbon Monoxide / Q000494:pharmacology; D002460:Cell Line; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006454:Hemoglobins / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology* / Q000502:physiology; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D015398:Signal Transduction; D013462:Sulfur Radioisotopes; D013601:T-Lymphocytes; D014316:Tritium; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D006454:Hemoglobins; D016328:NF-kappa B; D013462:Sulfur Radioisotopes; D014316:Tritium; D006153:Guanosine Diphosphate; D009569:Nitric Oxide; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D002248:Carbon Monoxide; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)