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 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 and therefore moves the [[Tropomyosin|tropomyosin]] away from the [[Myosin|myosin]] binding site on [[Actin|actin]]. This means that the two filaments can form a 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 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 a 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 specialised form another calcium ion binding protein, [[Calmodulin|calmodulin]], which is found in smooth muscle. The extra subunits, T and I, | 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, are responsible for the myosin heads being able to move towards the actin filaments very quickly for rapid contraction, This characteristic is useful in processes such as those that occur in [[Skeletal Muscle|skeletal muscle]], for example<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>. | ||
=== References === | === References === | ||
<references /> | <references /> | ||
Revision as of 21:33, 9 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 a 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, are responsible for the myosin heads being able to move towards the actin filaments very quickly for rapid contraction, This characteristic is useful in processes such as those that occur in skeletal muscle, for example[2].