Troponin C (TNC)
entry list
alignment
Troponin C (TNC) together with TNI and TNT form the heterotrimer,
troponin. It imparts calcium sensitivity to muscle. TNC has eleven
residues in the linker; hence, the F2 _-helix, linker, E3 _-helix is
eight turns long. TNC is dumbbell shaped in the apo form. The two
lobes of TNC in the Ca4-form enfold the target peptide of TNI, residues
1-47, [8] in a conformation similar to the CAM*target complex. Most
animals have several isoforms encoded at separate loci. In the
dendrograms based on both protein and DNA the vertebrate skeletal and
cardiac forms cluster separately indicating that the common precursor
of all vertebrates already has these two isoforms. Halocynthia, a
protochordate, has the most divergent TNC; its TNC clusters near the
base of the cardiac branch (figure 4).