Subcellular distribution and activation of rat submandibular cAMP-dependent protein kinase following beta-adrenergic receptor stimulation.
The extent of activation of rat submandibular protein kinase A (EC 2.7.1.37) isozymes following beta-adrenergic receptor stimulation was determined in vitro using dispersed cells and an 8-N3-[32P]cAMP photoprobe. The half-maximal binding of the photoprobe for microsomal and cytosolic type I and cytosolic type II was 9 nM, 27 nM and 92 nM, respectively. 'Cold trap' studies indicated that 70% of type I protein kinase A was activated following maximal beta-adrenergic receptor stimulation, whereas type II activation was less than 40%. Both cytosolic and microsomal type I activation occurred rapidly following beta-adrenergic receptor stimulation and both remain activated throughout the entire secretory period. Type I inactivation occurred rapidly subsequent to beta-adrenergic receptor blockade. The dose-response relationship for the isotypes following beta-adrenergic receptor activation demonstrated a greater extent of type I activation at submaximal concentrations of agonist. Although protein kinase A may not be the only kinase involved in rat submandibular mucin release, these data add further support to a direct regulatory role for this kinase, with type I having potentially a greater role than type II.
Quissell
D O
DO
Oral Sciences Research Center, University of Colorado Health Sciences Center, Aurora 80012.
Deisher
L M
LM
Barzen
K A
KA
D000818:Animals; D002451:Cell Compartmentation; D003080:Cold Temperature; D000242:Cyclic AMP / Q000096:biosynthesis; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D008861:Microsomes / Q000201:enzymology; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology; D013363:Submandibular Gland / Q000201:enzymology / Q000502:physiology*
D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D011494:Protein Kinases