Troponin: Difference between revisions
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Troponin complexes consist of three subunits - [[Troponin T|troponin T]] (also known as TnT or TNNT), [[Troponin I|troponin I]] (TnI or TNNI) and [[Troponin C|troponin C]] (TnC or TNNC). Troponin is therefore heterotrimeric, with each of the different subunits providing specific binding sites, allowing each troponin to | Troponin complexes consist of three subunits - [[Troponin T|troponin T]] (also known as TnT or TNNT), [[Troponin I|troponin I]] (TnI or TNNI) and [[Troponin C|troponin C]] (TnC or TNNC). Troponin is therefore heterotrimeric, with each of the different subunits providing specific binding sites, allowing each troponin to interact with a single molecule of [[Tropomyosin|tropomyosin]], an [[Actin|actin]] filament and a [[Calcium|Ca<sup>2+</sup>]] [[Ions|ion]] respectfully. The ability of the troponin C subunit to bind [[Ca2+ ion|Ca<sup>2+</sup>]] allows it to undergo a conformational change and therefore moves the [[Tropomyosin|tropomyosin]] away from the [[Myosin|myosin]] binding site on [[Actin|actin]]. This means that the two filaments can form an actin-myosin cross bridge<ref>Molecular Biology of the Cell, 4th edition Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter. 2002.</ref>. | ||
Troponin is thought to be a specialised form of another calcium ion binding protein, [[Calmodulin|calmodulin]], which is found in smooth muscle. The extra subunits, T and I, aid to propagate the movement of the myosin heads towards the actin filaments at great speed for rapid contraction, This characteristic is necessary in a number of processes, one example being action of the [[Skeletal Muscle|skeletal muscle]]<ref>Alberts, B. et al (2008) Molecular Biology of the Cell, 5th ed, Garland Science Taylor and Francis Group, New York, pp. 1028-1030</ref>. | |||
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Latest revision as of 09:10, 10 December 2018
Troponin complexes consist of three subunits - troponin T (also known as TnT or TNNT), troponin I (TnI or TNNI) and troponin C (TnC or TNNC). Troponin is therefore heterotrimeric, with each of the different subunits providing specific binding sites, allowing each troponin to interact with a single molecule of tropomyosin, an actin filament and a Ca2+ ion respectfully. The ability of the troponin C subunit to bind Ca2+ allows it to undergo a conformational change and therefore moves the tropomyosin away from the myosin binding site on actin. This means that the two filaments can form an actin-myosin cross bridge[1].
Troponin is thought to be a specialised form of another calcium ion binding protein, calmodulin, which is found in smooth muscle. The extra subunits, T and I, aid to propagate the movement of the myosin heads towards the actin filaments at great speed for rapid contraction, This characteristic is necessary in a number of processes, one example being action of the skeletal muscle[2].