title: Inhibition of MAPK pathway by a synthetic peptide corresponding to the activation segment of MAPK.
abstract: Mitogen-activated protein kinase (MAPK) is activated by phosphorylation within its activation segment. Upon phosphorylation, the activation segment refolds to provide the active conformation of the enzyme. We reported previously that a phosphorylation-sensitive secondary structure could be formed in a 26-amino-acid long synthetic peptide corresponding to the activation segment of Xenopus MAPK, termed IDA (Inter-DFG-APE) MAPK peptide (Tokmakov, A. A., et al. 1997, Biochem. Biophys. Res. Commun. 236, 243-247). Here, we show that unphosphorylated IDA MAPK peptide can inhibit in vitro both MAPK and MAPK kinase activities with the inhibition constants of 82 and 18 microM, respectively. Phosphorylated forms of the peptide were of little effect. IDA MAPK peptide did not inhibit significantly the activity of some other protein kinases, including MAPK homologue p38 kinase, suggesting the specificity for MAPK and MAPK kinase. Microinjection of unphosphorylated IDA MAPK peptide into immature Xenopus oocytes significantly suppressed progesterone-induced oocyte maturation by inhibiting activation of both MAPK and maturation promoting factor. Similar inhibition of maturation was registered upon oocyte treatment with another specific inhibitor of MAPK pathway, PD098059. These results depict IDA MAPK peptide as a selective inhibitor of the MAPK pathway that can be used for the investigations of MAPK-mediated signaling.
authors.affiliation: Biosignal Research Center, Kobe University, Nada, Kobe, 657-8501, Japan. tokmak@inherit.biosig.kobe-u.ac.jp
authors.forename: A A
authors.initials: AA
authors.lastname: Tokmakov
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Konaka
authors.forename: Y
authors.initials: Y
authors.lastname: Fukami
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D007700:Kinetics; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D010766:Phosphorylation; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014981:Xenopus; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D066246:ErbB Receptors; D017868:Cyclic AMP-Dependent Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases