Chymotryptic subfragments of troponin T from rabbit skeletal muscle. Interaction with tropomyosin, troponin I and troponin C.
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.
D000818:Animals; D002918:Chymotrypsin / Q000378:metabolism*; D002942:Circular Dichroism; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D011487:Protein Conformation; D011817:Rabbits; D014335:Tropomyosin / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*; D019209:Troponin C; D019210:Troponin I; D020107:Troponin T
D009124:Muscle Proteins; D010446:Peptide Fragments; D014335:Tropomyosin; D014336:Troponin; D019209:Troponin C; D019210:Troponin I; D020107:Troponin T; D002918:Chymotrypsin