Chymotryptic Subfragments of Troponin T from Rabbit Skeletal Muscle. Interaction with Tropomyosin, Troponin I and Troponin C1

Publisher Website
Google Scholar
Abstract
The binding of the chymotryptic troponin T subfragments to tropomyosin, troponin I, and troponin C was semiquantitatively examined by using affinity chromatography, and also by co-sedimentation with F-actin and polyacrylamide gel electrophoresis in 14 mM Tris/90 mM glycine. Circular dichroism spectra of the subfragments were measured to confirm that the subfragments retained their conformational structures. Based on these results, the binding sites of tropomyosin, troponin I, and troponin C on the troponin T sequence were elucidated. Tropomyosin bound mainly to the region of troponin T1 (residues 1–158) with the same binding strength as to the original troponin T. The C-terminal region of troponin T (residues 243–259) was the second binding site to tropomyosin under physiological conditions. The binding site of troponin I was concluded to be the region including residues 223–227. The binding of troponin C was dependent on Ca2+ ion concentration. The C-terminal region of troponin T2 (residues 159–259) was indicated to be the Ca2+-independent troponin C-binding site and the N-terminal side of troponin T2 to be the Ca2+-dependent site.