title: Selective inhibition of Ras interaction with its particular effector by synthetic peptides corresponding to the Ras effector region.
abstract: Ras proteins possess multiple downstream effectors of distinct structures. We and others demonstrated that Ha-Ras carrying certain effector region mutations could interact differentially with its effectors, implying that significant differences exist in their Ras recognition mechanisms. Here, by employing the fluorescence polarization method, we measured the activity of effector region synthetic peptides bearing various amino acid substitutions to inhibit association of Ras with the effectors human Raf-1 and Schizosaccharomyces pombe Byr2. The effect of these peptides on association with another effector Saccharomyces cerevisiae adenylyl cyclase was also examined by measuring inhibition of the Ras-dependent adenylyl cyclase activity. The peptide corresponding to the residues 17-44 competitively inhibited Ras association with all the three effectors at the Ki values of 1 approximately 10 microM, and the inhibition was considerably attenuated by the D38A mutation. The peptide with the D38N mutation inhibited association of Ha-Ras with Byr2 but not with the others, whereas that with the P34G mutation inhibited association of Ha-Ras with Raf-1 and Byr2 but not with adenylyl cyclase. Thus, the specificity observed with the whole Ras protein was retained in the effector region peptide. These results suggest that the effector region residues constitute a major determinant for differential recognition of the effector molecules, raising a possibility for selective inhibition of a particular Ras function.
authors.affiliation: Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ohnishi
authors.forename: Y
authors.initials: Y
authors.lastname: Yamawaki-Kataoka
authors.forename: K
authors.initials: K
authors.lastname: Kariya
authors.forename: M
authors.initials: M
authors.lastname: Tamada
authors.forename: C D
authors.initials: CD
authors.lastname: Hu
authors.forename: T
authors.initials: T
authors.lastname: Kataoka
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D005454:Fluorescence Polarization; D005656:Fungal Proteins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D020930:MAP Kinase Kinase Kinases; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins
chemical_list: D005656:Fungal Proteins; D010446:Peptide Fragments; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; D019908:Proto-Oncogene Proteins c-raf; C077892:BYR2 protein, S pombe; D020930:MAP Kinase Kinase Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D000262:Adenylyl Cyclases