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- Lopez-Aparicio, Pilar, et al.
(författare)
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Stimulation by insulin of a serine kinase in human platelets that phosphorylates and activates the cGMP-inhibited cAMP phosphodiesterase
- 1993
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 193:3, s. 1137-1144
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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