Troponin: Difference between revisions

Revision as of 20:54, 9 February 2025

Troponin

Mechanism of troponin activation

Troponin is a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle. Troponin is attached to the protein tropomyosin and lies within the groove between actin filaments in muscle tissue.

Structure

Troponin is composed of three subunits:

Troponin C (TnC): This subunit binds calcium ions and is responsible for the conformational change that allows muscle contraction to occur. It is similar to calmodulin in structure and function.

Troponin I (TnI): This subunit inhibits actin-myosin interactions, thus preventing muscle contraction in the absence of calcium.

Troponin T (TnT): This subunit binds the troponin complex to tropomyosin, anchoring it to the actin filament.

Function

Troponin plays a crucial role in the regulation of muscle contraction. When calcium ions are released from the sarcoplasmic reticulum, they bind to troponin C, causing a conformational change in the troponin complex. This change moves tropomyosin away from the actin binding sites, allowing myosin heads to bind to actin and initiate contraction.

Clinical Significance

Troponin levels are measured in the blood to diagnose myocardial infarction (heart attack). Elevated levels of cardiac-specific troponins (cTnI and cTnT) indicate damage to the heart muscle. These biomarkers are more specific and sensitive than previous markers such as creatine kinase (CK-MB).

Related Pages

References

Marieb, E. N., & Hoehn, K. (2018). Human Anatomy & Physiology. Pearson Education.
"Troponin." (2023). In Wikipedia, The Free Encyclopedia. Retrieved from https://en.wikipedia.org/wiki/Troponin

@@ Line 1: / Line 1: @@
-'''Troponin''' is a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle. Bundles of filaments, made up of myosin and actin, create these muscle contractions. It is a component of thin filaments (along with actin and tropomyosin).
+== Troponin ==
-==Structure==
+[[File:Troponin_Ribbon_Diagram.png|thumb|right|Ribbon diagram of troponin]]
-Troponin is attached to the protein tropomyosin and lies within the groove between actin filaments in muscle tissue. In a relaxed muscle, tropomyosin blocks the attachment site for the myosin crossbridge, thus preventing contraction. When the muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic reticulum and release calcium into the sarcoplasm. Some of this calcium attaches to troponin, which causes it to change shape, exposing binding sites for myosin (active sites) on the actin filaments.
+[[File:Troponin-activation.png|thumb|right|Mechanism of troponin activation]]
-==Function==
+'''Troponin''' is a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle. Troponin is attached to the protein tropomyosin and lies within the groove between actin filaments in muscle tissue.
-Troponin is found in both skeletal muscle and cardiac muscle, but the specific versions of troponin differ between types of muscle. The troponin complex is integral for muscle contraction. It is made up of three subunits: troponin I, troponin T, and troponin C. Each subunit serves a unique function.
-==Clinical significance==
+== Structure ==
-Troponin levels in the blood can become elevated if an event such as a heart attack causes damage to the heart muscle. Because of this, troponin tests are used to diagnose heart attacks and other conditions that damage the heart muscle.
-==See also==
+Troponin is composed of three subunits:
-* [[Myosin]]
-* [[Actin]]
+* '''Troponin C (TnC)''': This subunit binds calcium ions and is responsible for the conformational change that allows muscle contraction to occur. It is similar to calmodulin in structure and function.
+* '''Troponin I (TnI)''': This subunit inhibits actin-myosin interactions, thus preventing muscle contraction in the absence of calcium.
+* '''Troponin T (TnT)''': This subunit binds the troponin complex to tropomyosin, anchoring it to the actin filament.
+== Function ==
+Troponin plays a crucial role in the regulation of muscle contraction. When calcium ions are released from the sarcoplasmic reticulum, they bind to troponin C, causing a conformational change in the troponin complex. This change moves tropomyosin away from the actin binding sites, allowing myosin heads to bind to actin and initiate contraction.
+== Clinical Significance ==
+Troponin levels are measured in the blood to diagnose [[myocardial infarction]] (heart attack). Elevated levels of cardiac-specific troponins (cTnI and cTnT) indicate damage to the heart muscle. These biomarkers are more specific and sensitive than previous markers such as [[creatine kinase]] (CK-MB).
+== Related Pages ==
+* [[Muscle contraction]]
+* [[Calcium signaling]]
+* [[Myocardial infarction]]
 * [[Tropomyosin]]
-* [[Muscle contraction]]
-* [[Heart attack]]
-==References==
+== References ==
-<references />
+* Marieb, E. N., & Hoehn, K. (2018). ''Human Anatomy & Physiology''. Pearson Education.
+* "Troponin." (2023). In ''Wikipedia, The Free Encyclopedia''. Retrieved from https://en.wikipedia.org/wiki/Troponin
+{{Reflist}}
 [[Category:Proteins]]
-[[Category:Muscle tissue]]
+[[Category:Cardiac markers]]
-[[Category:Cardiology]]
-{{stub}}