The sites of phosphorylation of rabbit cardiac troponin I by adenosine 3′:5′-cyclic monophosphate-dependent protein kinase. Effect of interaction with troponin C

Publisher Website
Google Scholar
Abstract
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. Cyclic AMP-dependent protein kinase catalyzes phosphorylation at serine-20 and serine-146. Serine-20 is more rapidly phosphorylated than serine-146. 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. Phosphorylation at serine-20 and serine-146 is not significantly inhibited by troponin C. The mechanism of the interaction of troponin C with cardiac troponin I is discussed in light of these results.