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Troponin C, also known as TN-C or TnC, is a protein that resides in the troponin complex on actin thin filaments of striated muscle (cardiac, fast-twitch skeletal, or slow-twitch skeletal) and is responsible for binding calcium to activate muscle contraction. [5] [6] Troponin C is encoded by the TNNC1 gene in humans [7] for both cardiac and ...
Troponin T (blue) anchors the complex on tropomyosin. Troponin is found in both skeletal muscle and cardiac muscle, but the specific versions of troponin differ between types of muscle. The main difference is that the TnC subunit of troponin in skeletal muscle has four calcium ion-binding sites, whereas in cardiac muscle there are only three ...
Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction of muscles in the heart. [1] This process is of vital importance as it allows for the heart to beat in a controlled manner, without the need for conscious input.
Troponin (Tn), is a key protein complex in the regulation of striated muscle contraction, composed of three subunits. The TnI subunit inhibits actomyosin ATPase, the TnT subunit binds tropomyosin and TnC, while the TnC subunit binds calcium and overcomes the inhibitory action of the troponin complex on actin thin filaments.
Cardiac muscle troponin T (cTnT) is a protein that in humans is encoded by the TNNT2 gene. [ 5 ] [ 6 ] Cardiac TnT is the tropomyosin -binding subunit of the troponin complex, which is located on the thin filament of striated muscles and regulates muscle contraction in response to alterations in intracellular calcium ion concentration.
The action potential in a normal skeletal muscle cell is similar to the action potential in neurons. [61] Action potentials result from the depolarization of the cell membrane (the sarcolemma ), which opens voltage-sensitive sodium channels; these become inactivated and the membrane is repolarized through the outward current of potassium ions.
In cardiac muscle the T-tubules are only found at the Z-lines. [1] When an action potential causes cells to contract, calcium is released from the sarcoplasmic reticulum of the cells as well as the T tubules. The calcium release triggers sliding of the actin and myosin fibrils leading to contraction. [3]
In order for a muscle to contract, an action potential is first propagated down a nerve until it reaches the axon terminal of the motor neuron. The motor neuron then innervates the muscle fibers to contraction by causing an action potential on the postsynaptic membrane of the neuromuscular junction.