TNNI1 Human Native

Troponin I binds to actin in thin myofilaments to hold the actin-tropomyosin complex in place. This binding prevents myosin from interacting with actin in relaxed muscle, thereby inhibiting muscle contraction. When calcium ions bind to troponin C, it causes a conformational change that displaces troponin I, allowing muscle contraction to occur .

There are three isoforms of troponin I, each with unique tissue-specific expression patterns :

1. Slow-twitch skeletal muscle isoform (TNNI1): Found in slow-twitch skeletal muscles.
2. Fast-twitch skeletal muscle isoform (TNNI2): Found in fast-twitch skeletal muscles.
3. Cardiac muscle isoform (TNNI3): Found in cardiac muscles.

Troponin was first discovered in 1965 and was initially named ‘tropomyosin-like protein’. It was later purified and characterized from the skeletal muscles of a rabbit in 1973 . This discovery significantly advanced our understanding of muscle contraction mechanisms.

Troponin I is a valuable biomarker in the diagnosis of myocardial infarction (heart attack). Elevated levels of cardiac troponin I (cTnI) in the blood indicate cardiac muscle damage . However, it is important to note that troponin I is not entirely specific for myocardial damage secondary to infarction, as it can also be elevated in other conditions .

Recent research has focused on understanding the mechanisms behind troponin I release and its role in various diseases. High-sensitivity assays have improved the detection of troponin I, leading to better diagnostic accuracy .