Troponin c

Troponin C (TnC) is a part of the troponin complex, a group of three regulatory proteins (troponin C, troponin I, and troponin T) that are integral to muscle contraction in skeletal and cardiac muscle. Troponin C is the calcium binding component of the complex.

Structure

Troponin C is a small protein of about 18 kDa that binds calcium ions to regulate muscle contraction. It is composed of two domains, each of which can bind two calcium ions. The N-terminal domain is involved in regulating muscle contraction, while the C-terminal domain binds calcium ions in a calcium-dependent manner.

Function

The primary function of troponin C is to bind calcium ions and initiate muscle contraction. When calcium ions bind to troponin C, it undergoes a conformational change that allows it to bind to troponin I, inhibiting its interaction with actin and allowing muscle contraction to occur. In the absence of calcium, troponin C binds to troponin I, preventing it from interacting with actin and inhibiting muscle contraction.

Clinical significance

Troponin C is a key player in the regulation of muscle contraction, and alterations in its function can lead to a variety of muscle disorders. For example, mutations in the gene encoding troponin C have been associated with idiopathic dilated cardiomyopathy, a condition characterized by enlargement and weakening of the heart muscle. In addition, elevated levels of troponin C in the blood can be an indicator of heart damage, such as that which occurs during a myocardial infarction.

See also

• Troponin
• Troponin I
• Troponin T
• Muscle contraction
• Cardiomyopathy