Cyclic-AMP-dependent protein phosphorylation in the soluble fraction of parotid glands from rats with drug-induced hypothyroidism.
Cyclic-AMP-dependent protein kinase from the soluble fraction of parotid glands of hypothyroid rats was partially purified. Its isozyme distribution and kinetic properties were similar to those of euthyroid rats. Electrophoresis of 100 microliters portions at 20 mA per slab revealed that an endogenous protein (mol. wt 68,000) was specifically phosphorylated in hypothyroidism; this protein was not found in euthyroid rats. In the presence of cyclic AMP, there was stimulated phosphorylation of euthyroid-soluble proteins with molecular weights of 115,000, 98,000, 57,000, 50,000, 44,000, 33,000 and 19,000, and of proteins from hypothyroid rats with weights of 115,000, 98,000, 60,000, 50,000, 33,000 and 19,000. Tolbutamide reduced incorporation of 32Pi into soluble proteins from both groups. However, cyclic AMP still induced phosphorylation in euthyroid preparations in the presence of tolbutamide, but its effect was markedly reduced in the hypothyroid state. These differences in endogenous protein phosphorylation may have different effects on amylase release induced by beta-adrenergic stimulation.
D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D000242:Cyclic AMP / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007037:Hypothyroidism / Q000139:chemically induced / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D010306:Parotid Gland / Q000201:enzymology*; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011441:Propylthiouracil; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D010750:Phosphoproteins; D011441:Propylthiouracil; D000242:Cyclic AMP; D011494:Protein Kinases; D008274:Magnesium