title: Molecular structure of troponin C from chicken skeletal muscle at 3-angstrom resolution.
abstract: The x-ray structure of chicken skeletal muscle troponin C (TnC), the Ca2+-binding subunit of the troponin complex, shows that the protein is about 70 angstroms long with an unusual dumbbell shape. The carboxyl and amino domains are separated by a single long alpha helix of about nine turns. Only the two high-affinity Ca2+-Mg2+ sites of the COOH-domain are occupied by metal ions resulting in conformational differences between the COOH- and NH2-domains. These differences are probably important in the triggering of muscle contraction by TnC. Also the structure of TnC is relevant in understanding the function of other calcium-regulated proteins, in particular that of calmodulin because of its strong similarity in amino acid sequence.
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000502:physiology; D002645:Chickens; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology / Q000648:ultrastructure; D011487:Protein Conformation; D014336:Troponin / Q000502:physiology*; D019209:Troponin C; D014422:Turkeys; D014961:X-Ray Diffraction
chemical_list: D002147:Calmodulin; D014336:Troponin; D019209:Troponin C