NCIt definition : Troponin I, troponin T, and troponin C are the three closely associated subunits of
the troponin complex of thin filaments in muscle. The complex serves as a calcium-sensitive
switch that regulates muscle contraction. In the absence of calcium, Troponin I binds
actin, inhibits actomyosin ATPase activity, and inhibits F-actin-myosin interactions.
The troponin I gene family comprises three isoforms: skeletal TNI-fast, skeletal TNI-slow,
and TNI-cardiac. (from OMIM 191044, 191043, 191042 and NCI);