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Stimulation by insulin of a serine kinase in human platelets that phosphorylates and activates the cGMP-inhibited cAMP phosphodiesterase

Author:
  • Pilar Lopez-Aparicio
  • Per Belfrage
  • Vincent C Manganiello
  • Tetsuro Kono
  • Eva Degerman
Publishing year: 1993
Language: English
Pages: 1137-1144
Publication/Series: Biochemical and Biophysical Research Communications
Volume: 193
Issue: 3
Document type: Journal article
Publisher: Elsevier

Abstract english

We previously reported that insulin stimulation of human platelets induces serine phosphorylation and activation of the cGMP-inhibited cAMP phosphodiesterase (cGI-PDE). Here, we describe methods to detect and partially purify an insulin-stimulated cGI-PDE kinase (cGI-PDE ISK) from lysates of platelets incubated with insulin. Incubation of human platelets with 10(-8) M insulin increased cGI-PDE ISK activity two-fold. The DEAE-Sephacel-purified cGI-PDE ISK phosphorylated the cGI-PDE on serine in a time- and concentration-dependent manner resulting in an increased incorporation of about 0.2 mol of [32P]/mol of cGI-PDE and 15-20% increase in cGI-PDE activity. The phosphorylation of cGI-PDE was not affected by 10 microM PKI, 1 microgram/ml of heparin, 3 mM CaCl2 or 1 mM MnCl2. cGI-PDE ISK did not adsorb to antiphosphotyrosine antibodies. To maintain its activation it was necessary to add protein phosphatase inhibitors to the lysate-buffers. All of these findings are consistent with the conclusion that a serine/threonine phosphorylation of the cGI-PDE ISK is involved in its activation by insulin.

Keywords

  • Biological Sciences

Other

Published
  • Insulin Signal Transduction
  • ISSN: 1090-2104
Eva Degerman
E-mail: eva [dot] degerman [at] med [dot] lu [dot] se

Professor

Insulin Signal Transduction

+46 46 222 85 83

+46 70 885 83 62

BMC C1121b

66

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