Ectoprotein kinase-mediated phosphorylation of FAT/CD36 regulates palmitate uptake by human platelets |
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Authors: | Guthmann F Maehl P Preiss J Kolleck I Rüstow B |
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Institution: | Klinik für Neonatologie, Charité-CCM, Humboldt-Universit?t zu Berlin, 10098 Berlin, Germany. florian.guthmann@charite.de |
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Abstract: | Glycoprotein IV (FAT/CD36) has been shown to be phosphorylated by a cAMP-dependent, platelet membrane-bound ectokinase. In
this study, we demonstrate that ectophosphorylation of FAT/CD36 regulates initial palmitate uptake. This is the first time
that short-term regulation of the activity of a long-chain fatty acid carrier could be shown. Phosphorylation of FAT/CD36
was paralleled by a significant decrease in initial palmitate uptake by morphologically and functionally intact platelets.
Maximum inhibition of palmitate uptake was achieved at 0.5 nM extracellular ATP, being significantly decreased to 72% compared
to the control. Inhibition of palmitate uptake was abolished by co-incubation with the specific protein kinase A inhibitor
peptide PKI or with β,γ-methylene-ATP, and was reversible upon addition of alkaline phosphatase. An extracellular ATP concentration
above 5 μM completely prevented the ectophosphorylation-mediated inhibition of palmitate uptake. We conclude that FAT/CD36-mediated
palmitate uptake by human platelets is short-term regulated via cAMP-dependent ectophosphorylation of FAT/CD36.
Received 18 July 2002; received after revision 29 August 2002; accepted 19 September 2002
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ID="*"Corresponding author. |
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Keywords: | , Ectoprotein kinase, purinergic receptor, adenylyl-(β,,γ,-methylene)triphosphate, long-chain fatty acid, transmembrane,,,,,transport, |
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