Troponin C (TnC) is part of the troponin protein complex. There are two subtypes in humans: Troponin C, slow skeletal and cardiac muscles (TNNC1) (3p21.1 ) Troponin C, skeletal muscle (TNNC2) (20q12-q13.11, ) 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.
TnC is structurally similar to calmodulin and myosin light chain. These three groups of proteins form a family.
See also Troponin T Troponin I Calcium-binding protein Sliding filament model
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