Troponin C is a protein which is part of the troponin complex. It contains four calcium-binding EF hands, although different isoforms may have fewer than four functional calcium-binding subdomains. It is a component of thin filaments, along with actin and tropomyosin. It contains an N lobe and a C lobe. The C lobe serves a structural purpose and binds to the N domain of troponin I (TnI). The C lobe can bind either Ca2 or Mg2 . The N lobe, which binds only Ca2 , is the regulatory lobe and binds to the C domain of troponin I after calcium binding.
Isoforms
The tissue specific subtypes are:
- Slow troponin C, TNNC1 (3p21.1 Online Mendelian Inheritance in Man (OMIM): 191040)
- Fast troponin C, TNNC2 (20q12-q13.11, Online Mendelian Inheritance in Man (OMIM): 191039)
Mutations
Point mutations can occur in troponin C inducing alterations to Ca2 and Mg2 binding and protein structure, leading to abnormalities in muscle contraction. In cardiac muscle, they are related to dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM).
These known point mutations are:
- A8V
- D145E
- A31S
- C84Y
- E134D
- Y5H
- I148V
See also
- Troponin
- Troponin T
- Troponin I
- Calcium-binding protein
- Sliding filament model
References
External links
- Troponin C at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
