Scientific article
Open access

Functional inhibition of protein kinase C-mediated effects in myocardial tissue is due to the phosphatase 2A

Published inBiochemical journal, vol. 286 (Pt 3), p. 851-855
Publication date1992

An endogenous protein which inhibits protein kinase C (PKC)-mediated effects has been detected in rat heart ventricular tissue. This functional PKC-inhibitory activity was completely abolished by okadaic acid, making it possible to measure PKC activity in non-purified cell fractions. This suggests that the PKC-inhibitory activity is a type 1 or 2A serine/threonine phosphatase. Confirming this, membrane and cytosolic PKC-inhibitory preparations were found to contain phosphatase activity which was suppressed by okadaic acid, exhibiting an IC50 (concn. required for 50% inhibition) of 1.5-2 nM. Furthermore, okadaic acid stimulated prostacyclin production in rat cardiomyocytes and aortic smooth-muscle cells and, like the PKC activator phorbol 12-myristate 13-acetate, it augmented the prostacyclin formation induced by the Ca2+ ionophore A23187. Our results strongly suggest that the endogenous PKC 'inhibitor' is the cellular phosphatase 2A, which plays an important role in regulating the phosphorylation level of PKC target proteins.

  • Animals
  • Cells, Cultured
  • Chromatography, DEAE-Cellulose
  • Epoprostenol/biosynthesis
  • Ethers, Cyclic/pharmacology
  • Female
  • Muscle, Smooth, Vascular/cytology/metabolism
  • Myocardium/cytology/metabolism
  • Okadaic Acid
  • Phosphoprotein Phosphatases/antagonists & inhibitors/metabolism
  • Protein Kinase C/antagonists & inhibitors
  • Protein Phosphatase 2
  • Rats
  • Rats, Wistar
Citation (ISO format)
BRACONI QUINTAJE, Silvia et al. Functional inhibition of protein kinase C-mediated effects in myocardial tissue is due to the phosphatase 2A. In: Biochemical journal, 1992, vol. 286 (Pt 3), p. 851–855.
Main files (1)
Article (Accepted version)
ISSN of the journal0264-6021

Technical informations

Creation03/17/2009 12:34:00 PM
First validation03/17/2009 12:34:00 PM
Update time03/14/2023 3:03:25 PM
Status update03/14/2023 3:03:25 PM
Last indexation01/15/2024 6:18:14 PM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack