Phosphorylation of the inhibitory subunit of troponin in perfused hearts of mice deficient in phosphorylase kinase. Evidence for the phosphorylation of troponin by adenosine 3':5'-phosphate-dependent protein kinase in vivo.
When hearts from control and phosphorylase kinase-deficient (I strain) mice were perfused with 0.1 micrometer-DL-isoprenaline, there was a parallel increase in contraction, cyclic AMP concentration and troponin I phosphorylation. However, there was no increase in phosphorylase a in the I-strain hearts, whereas the control hearts showed a large increase. Assays of I-strain heart extracts showed a normal cyclic AMP-dependent protein kinase activity but no phosphorylase kinase activity. It is concluded that troponin I is phosphorylated in intact hearts by protein kinase and not phosphorylase kinase.
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D009124:Muscle Proteins / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010764:Phosphorylase Kinase / Q000172:deficiency*; D011494:Protein Kinases / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*
D009124:Muscle Proteins; D010710:Phosphates; D014336:Troponin; D000242:Cyclic AMP; D011494:Protein Kinases; D010764:Phosphorylase Kinase