Troponin C Explained

Troponin C
Test Of:	Troponin

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

Troponin C, slow skeletal and cardiac muscles
Symbol:	TNNC1
Hgncid:	11943
Omim:	191040
Refseq:	NM_003280
Uniprot:	P63316
Chromosome:	3
Arm:	p
Band:	21.1

Troponin C, skeletal muscle
Symbol:	TNNC2
Hgncid:	11944
Omim:	191039
Refseq:	NP_003270.1
Uniprot:	P02585
Chromosome:	20
Arm:	q
Band:	13.12

The tissue specific subtypes are:

• Slow troponin C, TNNC1 (3p21.1)
• Fast troponin C, TNNC2 (20q12-q13.11,)

Mutations

Point mutations can occur in troponin C inducing alterations to Ca²⁺ and Mg²⁺ binding and protein structure,^[1] leading to abnormalities in muscle contraction.^{[2] [3]} 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

Notes and References

1. Kalyva A, Parthenakis FI, Marketou ME, Kontaraki JE, Vardas PE . Biochemical characterisation of Troponin C mutations causing hypertrophic and dilated cardiomyopathies . Journal of Muscle Research and Cell Motility . 35 . 2 . 161–78 . April 2014 . 24744096 . 10.1007/s10974-014-9382-0 . 1726747 .
2. Cheng Y, Regnier M . Cardiac troponin structure-function and the influence of hypertrophic cardiomyopathy associated mutations on modulation of contractility . Archives of Biochemistry and Biophysics . 601 . 11–21 . July 2016 . 26851561 . 4899195 . 10.1016/j.abb.2016.02.004 . Special Issue: Myofilament Modulation of Contraction .
3. Pinto JR, Parvatiyar MS, Jones MA, Liang J, Ackerman MJ, Potter JD . A functional and structural study of troponin C mutations related to hypertrophic cardiomyopathy . The Journal of Biological Chemistry . 284 . 28 . 19090–100 . July 2009 . 19439414 . 2707221 . 10.1074/jbc.M109.007021 . free .