What is troponin?
1 Answer
Aug 7, 2014
Troponin (a protein) is attached to the protein tropomyosin and lies within the groove between actin filaments in muscle tissue. It "hides" or blocks the binding sites so that muscle contraction can not occur.
When the muscle cell is stimulated to contract, calcium channels open and release calcium into the sarcoplasm.
Some of this calcium attaches to troponin, which causes it to change shape, exposing binding sites for myosin (active sites) on the actin filaments.
Myosin's binding to actin causes cross bridge formation, and contraction of the muscle begins.
Troponin is found in both skeletal muscle and cardiac muscle but not smooth muscle.
