title: Protein kinase activation as an early event in the trans-synaptic induction of tyrosine 3-monooxygenase in adrenal medulla.
abstract: An increase of cAMP/cGMP concentration ratio is the earliest stimulus-coupled biochemical change that has been measured in the adrenal medulla during the trans-synaptic induction of tyrosine 3-monooxygenase [EC 1.14.16.2; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating)]. In adrenal medulla of rats receiving reserpine alone (16 mumol/kg intraperitoneally) or reserpine and propranolol (40 mumol/kg intraperitoneally 30 min before reserpine), or exposed to 4 degrees for 4 hr, the extent and duration of the increase of the cAMP/cGMP concentration ratio exceeds the critical value that is required to activate the protein kinases (EC 2.7.1.37; ATP:protein phosphotransferase). Gel filtration experiments indicate that during this activation, the catalytic subunit of the protein kinase (low-molecular-weight enzyme) is released from the holoenzyme. The activation of protein kinase lasts longer than the increase in the cAMP/cGMP concentration ratio and appears to be an obligatory early event that mediates the increase of tyrosine monooxygenase synthesis. The trans-synaptic induction of the monooxygenase in adrenal medulla appears to be due to an increased synthesis of the enzyme;the rate for monooxygenase degradation is proportional to the number of enzyme molecules that are present at various stages of the induction process.
mesh_terms: D000313:Adrenal Medulla / Q000201:enzymology* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation; D004790:Enzyme Induction; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D012110:Reserpine / Q000494:pharmacology; D013569:Synapses; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
chemical_list: D012110:Reserpine; D011433:Propranolol; D000242:Cyclic AMP; D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases