Substrates for adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase in the rat pituitary gland.
1. Substrates for cAMP-dependent protein kinase were investigated in anterior, intermediate, and neural lobes of the rat pituitary gland. In a cell-free assay system, cAMP increased phosphorylation of 17 K, 33 K, and 60 K macromolecules of the anterior lobe, 17 K, 33 K, 60 K, and 80 K macromolecules of the intermediate lobe, and 60 K, 80 K, and 85 K macromolecules of the neural lobe. 2. Other nucleotides were tested in the intermediate lobe; 8 Br-cAMP mimicked cAMP, cGMP was much less effective than cAMP or 8 Br-cAMP, and 5'-AMP showed no significant effect. The purified catalytic subunit of cAMP-dependent protein kinase evoked the same phosphorylation pattern as the endogenous kinase. 3. Maximum cAMP-dependent phosphorylation occurred at between 1 and 2 min of incubation; after 20 min, phosphorylation was reduced by 80%. This suggests the presence of phosphatase activity in the intermediate lobe. 4. When tested upon dispersed intermediate lobe cells permeabilized by high-voltage electrical discharges, cAMP increased phosphorylation of the 17 K and 33 K macromolecules.
Furuki
Y
Y
Experimental Therapeutic Branch, Bethesda, Maryland 20892.
Yamamoto
T
T
Guild
S
S
Kebabian
J W
JW
D000818:Animals; D002474:Cell-Free System; D000242:Cyclic AMP / Q000494:pharmacology; D010766:Phosphorylation; D010902:Pituitary Gland / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000242:Cyclic AMP; D011494:Protein Kinases