Differences in phorbol ester-induced decrease of the activity of protein kinase C isozymes in rat hepatocytes
Por:
Robles-Flores M., Alcántara-Hernández R., García-Sáinz J.A.
Publicada:
1 ene 1991
Resumen:
Two main forms of protein kinase C (PKC) activity were found in rat hepatocytes using DEAE-cellulose chromatography: PKC 1 and PKC 2. Treatment of cells with 1 µM 12-O-tetradecanoylphorbol 13-acetate (TPA) for 15 min caused a marked loss of PKC 1 activity and only a small loss of PKC 2 activity. Hydroxyapatite column chromatography resolved PKC 1 into three distinct peaks 1a, 1b and 1c, and PKC 2 into four peaks 2a, 2b, 2c and 2d. Immunoblot analysis with isozyme-specific monoclonal antibodies identified peak 1a as PKC-ß and peak 1b as PKC-a; the other peaks of activity were not identified. Treatment with TPA provoked a loss of activity of peaks 1b (PKC-a) and 1c, whereas peak 1a (PKC-ß) activity was not affected. The peaks of activity corresponding to PCK 2 did not show any major change due to TPA treatment except peak 2d that decreased. The apparent disappearance of PKC histone-kinase activity induced by TPA was also observed using other substrates (protamine or vinculin). The TPA-induced decrease in activity occurs in a time-dependent and dose-dependent fashion. However, the time-courses, the extent of depletion and the potency order of phorbol esters in induction of an activity decrease in the two groups of isoforms exhibited substantial differences. © 1991.
Filiaciones:
Robles-Flores M.:
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, Mexico
Alcántara-Hernández R.:
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, Mexico
García-Sáinz J.A.:
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, Mexico
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