UNIPROT #

P19429

PROTEIN NAME

Cardiac Troponin I

SYNONYMS

cardiac muscle antibody; Cardiac troponin I antibody; cardiomyopathy, dilated 2A (autosomal recessive) antibody; Cardiomyopathy, familial hypertrophic, 7, included antibody; CMD1FF antibody; CMD2A antibody; CMH7 antibody; cTnI antibody; Familial hypertrophic cardiomyopathy 7 antibody; MGC116817 antibody; RCM1 antibody; Tn1 antibody; Tni antibody; TNN I3 antibody; TNNC 1 antibody; TNNC1 antibody; TNNI3 antibody; TNNI3_HUMAN antibody; Troponin I antibody; Troponin I cardiac antibody; Troponin I cardiac muscle antibody; Troponin I cardiac muscle isoform antibody; Troponin I type 3 cardiac antibody; troponin I, cardiac 3 antibody; TroponinI antibody; Ttroponin I type 3 (cardiac) antibody

SEQUENCE SIMILARITIES

Belongs to the troponin I family.

POST-TRANSLATIONAL MODIFICATION

Phosphorylated at Ser-42 and Ser-44 by PRKCE; phosphorylation increases myocardium contractile dysfunction (By similarity). Phosphorylated at Ser-23 and Ser-24 by PRKD1; phosphorylation reduces myofilament calcium sensitivity. Phosphorylated preferentially at Thr-31. Phosphorylation by STK4/MST1 alters its binding affinity to TNNC1 (cardiac Tn-C) and TNNT2 (cardiac Tn-T).

SUBCELLULAR LOCATION

Cytosol.

FUNCTION

Actin is a highly conserved protein that is expressed in all eukaryotic cells. Actin filaments can form both stable and labile structures and are crucial components of microvilli and the contractile apparatus of muscle cells. Myosin is a hexamer composed of two heavy chains (MHC) and four light chains (MLC); it interacts with Actin to generate the force for diverse cellular movements, including cytokinesis, phagocytosis and muscle contraction. Troponin facilitates the interaction between Actin and Myosin by binding to calcium. Troponin comprises at least two subunits, which are divergent in cardiac muscle, fast skeletal muscle and slow skeletal muscle. Structures of skeletal muscle troponin are composed of Troponin C (the sensor), Troponin I (the regulator) and Troponin T (the link to the muscle thin filament). Troponin C is dumbbell-shaped and has a hydrophobic pocket that increases the contractile force of muscle fibers. Troponin C has two isoforms: fast and slow. Fast Troponin C has two calcium binding sites while slow/cardiac Troponin C has a single calcium binding site.