Troponin-C Protein

Troponin-C is encoded by the TNNC1 gene in humans and is found on the actin thin filaments of striated muscle, including cardiac and slow-twitch skeletal muscle . The primary function of cTnC is to bind calcium ions, which triggers a series of structural changes in the troponin complex. This binding causes troponin I to release its inhibition of actin-myosin interactions, allowing muscle contraction to occur .

In cardiac muscle, cTnC has three calcium-binding sites, compared to four in skeletal muscle. This difference is significant as it influences the sensitivity and regulation of muscle contraction in response to calcium levels .

Cardiac troponins, including cTnC, are highly specific biomarkers for myocardial injury. Elevated levels of cardiac troponins in the blood are indicative of myocardial infarction (heart attack) and other forms of cardiac injury . The development of high-sensitivity cardiac troponin assays has revolutionized the diagnosis and management of acute coronary syndromes (ACS) by allowing for the early detection of even minor myocardial injuries .

The measurement of cardiac-specific troponins I and T is extensively used as diagnostic and prognostic indicators in the management of myocarditis, myocardial infarction, and acute coronary syndrome . Elevated cTn levels are also observed in chronic diseases and conditions not directly related to acute coronary events, reflecting myocardial injury of various origins .

Research into the mechanisms of troponin release and its role in non-acute conditions is ongoing. Understanding these mechanisms is crucial for improving the specificity and utility of troponin assays in clinical practice . Additionally, the ability to detect increased cTn levels following extreme exercise has raised questions about the traditional understanding of troponin release and its implications for cardiac health .