Ca-dependent regulation of the subunit exchange of F-actin under the influence of tropomyosin and troponin.


A quasi-steady state rate of actin subunit incorporation into a complex of F-actin, tropomyosin, and troponin was studied in a solution containing MgCl2 0.5 mM, ATP 0.2 mM, Tris-HCl 5 mM (pH 8.0), and either CaCl2 64 muM or EGTA 644 muM at 33 degrees C by adding a small amount (less than 1 muM) of fluorescence-labeled actin monomer. Incorporation of the… (More)