title: Further characterization of galloyl pedunculagin as an effective autophosphorylation inhibitor of C-kinase in vitro.
abstract: The inhibitory effect of galloyl pedunculagin (GP) isolated from Platycarya strobilacea on the activity and autophosphorylation of Ca(2+)- and phospholipid-dependent protein kinase (C-kinase) was examined in vitro. It was found that (i). GP inhibited the activity (phosphorylation of complement C3 from guinea pig) of C-kinase alpha (rat brain) in a dose-dependent manner with an ID(50) of approx. 0.12 micro M (ii). GP at lower doses (ID(50)=approx. 6 nM) inhibited autophosphorylation of C-kinase alpha; and (iii). the GP-induced inhibition of autophosphorylation of C-kinase alpha and its enzyme activity was a manner non-competitive to ATP. Similar inhibitory effect of GP on autophosphorylation of recombinant human C-kinase eta (rhC-kinase eta) and its phosphorylating activity was observed. These results suggest that GP is an effective autophosphorylation inhibitor of these two C-kinase isoforms (alpha and eta) in vitro. In addition, the CD analysis suggests that the proline-containing six amino acid residues (PVLTPP) including a threonine residue (autophosphorylation site) at the C-terminal region (positions 635-640) of C-kinase alpha may be one of the GP-binding sites.
authors.affiliation: Genetical Biochemistry, Graduate School of Medical Sciences, Kitasato University.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueno
authors.forename: Takahiro
authors.initials: T
authors.lastname: Miyanaga
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Kawakami
authors.forename: Maiko
authors.initials: M
authors.lastname: Okano
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Kenzo
authors.initials: K
authors.lastname: Ohtsuki
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D006168:Guinea Pigs; D006801:Humans; D047348:Hydrolyzable Tannins; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D013634:Tannins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D047348:Hydrolyzable Tannins; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D010936:Plant Extracts; D013634:Tannins; C013515:ellagitannin; C015482:protein kinase modulator; D011493:Protein Kinase C