Troponin I: Difference between revisions
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Troponin is an accessory [[Protein|protein]] found in [[Thin filaments|thin filaments]] | Troponin is an accessory [[Protein|protein]] found in [[Thin filaments|thin filaments]] (also known as actin filaments). Thin filaments are structural components of a repeating unit called the [[Sarcomere|sarcomere]]. These thin filaments play an important role in [[Muscle_contraction|muscle contraction]]. Troponin consists of three sub-units; [[Troponin T|troponin T]], I and [[Troponin C|C]]. When the muscle is at rest the T and I sub-units bind to [[Tropomyosin|tropomyosin]] and [[Actin|actin]] resulting in an inhibitory process that prevents [[Myosin|myosin]] heads from binding to actin. When the concentration of [[Calcium_ions|calcium ions]] raises in the [[Cytoplasm|cytoplasm]], due to the influx from the [[Sarcoplasmic reticulum|sarcoplasmic reticulum]], the calcium ions bind to [[Troponin C|troponin C]]<ref>Alberts, B. et al., 2008. Molecular Biology of the Cell, Fourth Edition 5th Edition., New York, USA: Garland Publishing Inc.</ref>. This binding causes troponin I to release its hold on actin, which allows tropomyosin to move back to its normal position. Consequently, the [[Myosin|myosin]] binding site is uncovered, allowing myosin heads to bind to [[Actin|actin]] and form a [[Cross_bridge|cross bridge]], triggering contraction<ref>Alberts,Bruce et al. (2002) Molecular biology of the cell 4th ed. (chapter 16 pg 962-965). New York, Garland Science.</ref>. | ||
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Latest revision as of 18:25, 15 November 2018
Troponin is an accessory protein found in thin filaments (also known as actin filaments). Thin filaments are structural components of a repeating unit called the sarcomere. These thin filaments play an important role in muscle contraction. Troponin consists of three sub-units; troponin T, I and C. When the muscle is at rest the T and I sub-units bind to tropomyosin and actin resulting in an inhibitory process that prevents myosin heads from binding to actin. When the concentration of calcium ions raises in the cytoplasm, due to the influx from the sarcoplasmic reticulum, the calcium ions bind to troponin C[1]. This binding causes troponin I to release its hold on actin, which allows tropomyosin to move back to its normal position. Consequently, the myosin binding site is uncovered, allowing myosin heads to bind to actin and form a cross bridge, triggering contraction[2].