title: Quercetin inhibits tyrosine phosphorylation by the cyclic nucleotide-independent, transforming protein kinase, pp60src.
abstract: The bioflavonoid quercetin is a potent inhibitor of a cyclic nucleotide-independent, tumor virus-coded protein kinase which phosphorylates tyrosine residues and acts as a cellular transforming protein. Half-maximal inhibition of the protein kinase occurred at 3-4 microM quercetin whereas rutin was much less effective. The finding, that quercetin inhibits a cyclic nucleotide-independent protein kinase activity, may provide clues to the diverse pharmacological effects of the bioflavonoids.
mesh_terms: D000242:Cyclic AMP / Q000502:physiology; D005419:Flavonoids / Q000494:pharmacology*; D015688:Oncogene Protein pp60(v-src); D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011794:Quercetin / Q000494:pharmacology*; D014443:Tyrosine / Q000378:metabolism*; D014764:Viral Proteins / Q000037:antagonists & inhibitors*
chemical_list: D005419:Flavonoids; D047428:Protein Kinase Inhibitors; D014764:Viral Proteins; D014443:Tyrosine; D011794:Quercetin; D000242:Cyclic AMP; D015688:Oncogene Protein pp60(v-src)