Titin: a protein kinase that is abundant in striated muscle. Is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. A N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere respectively so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Mutations are associated with familial hypertrophic cardiomyopathy 9 and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma.
Protein type: CAMK group; EC 2.7.11.1; Kinase, protein; MLCK family; Protein kinase, CAMK; Protein kinase, Ser/Thr (non-receptor)
Chromosomal Location of Human Ortholog: 2q31.2
Cellular Component: condensed nuclear chromosome; cytosol; extracellular region; I band; muscle myosin complex; Z disc
Molecular Function: actin filament binding; actinin binding; calcium ion binding; calmodulin binding; enzyme binding; identical protein binding; muscle alpha-actinin binding; protease binding; protein binding; protein kinase binding; protein self-association; protein serine/threonine kinase activity; protein-tyrosine kinase activity; structural constituent of muscle; telethonin binding
Biological Process: cardiac muscle contraction; cardiac muscle fiber development; cardiac muscle morphogensis; cardiac myofibril assembly; mitotic chromosome condensation; muscle contraction; muscle filament sliding; muscle thick filament assembly; muscle thin filament assembly; platelet degranulation; regulation of catalytic activity; regulation of protein kinase activity; response to calcium ion; sarcomere organization; sarcomerogenesis; striated muscle contraction
Disease: Cardiomyopathy, Dilated, 1g; Hereditary Myopathy With Early Respiratory Failure; Muscular Dystrophy, Limb-girdle, Type 2j; Myopathy, Early-onset, With Fatal Cardiomyopathy; Tibial Muscular Dystrophy, Tardive
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