title: Probing the structure and mechanism of Ras protein with an expanded genetic code.
abstract: Mutations in Ras protein at positions Gly12 and Gly13 (phosphate-binding loop L1) and at positions Ala59, Gly60, and Gln61 (loop L4) are commonly associated with oncogenic activation. The structural and catalytic roles of these residues were probed with a series of unnatural amino acids that have unusual main chain conformations, hydrogen bonding abilities, and steric features. The properties of wild-type and transforming Ras proteins previously thought to be uniquely associated with the structure of a single amino acid at these positions were retained by mutants that contained a variety of unnatural amino acids. This expanded set of functional mutants provides new insight into the role of loop L4 residues in switch function and suggests that loop L1 may participate in the activation of Ras protein by effector molecules.
authors.affiliation: Department of Chemistry, University of California, Berkeley 94720.
authors.forename: H H
authors.initials: HH
authors.lastname: Chung
authors.forename: D R
authors.initials: DR
authors.lastname: Benson
authors.forename: P G
authors.initials: PG
authors.lastname: Schultz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular / Q000379:methods; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D020690:GTPase-Activating Proteins; D011905:Genes, ras; D006860:Hydrogen Bonding; D008715:Methionine / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D011506:Proteins; D011994:Recombinant Proteins; D020703:ras GTPase-Activating Proteins; D008715:Methionine; D020558:GTP Phosphohydrolases; D016283:Proto-Oncogene Proteins p21(ras)