Troponin C

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.

Cardiac sarcomere structure, featuring troponin C

Troponin C
Test of	Troponin

Troponin

Isoforms

Troponin C, slow skeletal and cardiac muscles
Identifiers
Symbol	TNNC1
HGNC	11943
OMIM	191040
RefSeq	NM_003280
UniProt	P63316
Other data
Locus	Chr. 3 p21.1
Search for Structures Swiss-model Domains InterPro

Troponin C, skeletal muscle
Identifiers
Symbol	TNNC2
HGNC	11944
OMIM	191039
RefSeq	NP_003270.1
UniProt	P02585
Other data
Locus	Chr. 20 q13.12
Search for Structures Swiss-model Domains InterPro

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,^[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