The sites of phosphorylation of rabbit cardiac troponin I by adenosine 3':5'-cyclic monophosphate-dependent protein kinase. Effect of interaction with troponin C.
1. Troponin I prepared from rabbit hearts contains 1.0-1.5 mol of P/mol when isolated by affinity chromatography. Most of the covalently bound phosphate is located in residues 1-48 of the molecule. 2. 3':5'-Cyclic AMP-dependent protein kinase catalyses phosphorylation at serine-20 and serine-146. Serine-20 is more rapidly phosphorylated than serine-146. 3. In troponin I prepared from frozen hearts by affinity chromatography about 0.3-0.5 mol of P/mol is associated with serine-20 and 0.8-1.0 mol of P/mol with other site(s) in residues 1-48 of the molecule. 4. Phosphorylation at serine-20 and servine-146 is not significantly inhibited by troponin C. 5. The mechansim of the interaction of troponin C with cardiac troponin I is discussed in the light of these results.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002850:Chromatography, Gel; D000242:Cyclic AMP; D009124:Muscle Proteins / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits; D012694:Serine / Q000378:metabolism; D014336:Troponin / Q000378:metabolism*
D000596:Amino Acids; D009124:Muscle Proteins; D010710:Phosphates; D010750:Phosphoproteins; D014336:Troponin; D012694:Serine; D000242:Cyclic AMP; D011494:Protein Kinases