Title: Titin
Additional Names: Connectin
Literature References: Giant, elastic protein found in vertebrate skeletal and cardiac muscles; comprises ~10% of the myofibrillar mass. One of the largest polypeptides known; mol wt: ~3 ยด 106 Da. Structure consists of repeats of 2 motifs, each with approximately 100 amino acid residues, organized into a super-repeating pattern. Enriched in proline (8-9 mole %) which contributes to its flexibility. Integral component of the cytoskeletal lattice of muscle cells (see also Nebulin). Thought to act as a "molecular ruler" that regulates the assembly of myosin and other thick filament proteins; connects the ends of the thick filament with the Z-line. Also responsible for the generation of resting tension in stretched muscle fibers. Identification in rabbit muscle: K. Maruyama et al., Nature 262, 58 (1976). Characterization and localization in myofibrils: K. Wang et al., Proc. Natl. Acad. Sci. USA 76, 3698 (1979). Purification methods: K. Wang, Methods Enzymol. 85B, 264 (1982). Distribution and organization in the cytoskeletal matrix of striated muscle: idem, Adv. Exp. Med. Biol. 170, 285-305 (1984). Quantitative determn in muscle fibers by gel electrophoresis: H. L. M. Granzier, K. Wang, Electrophoresis 14, 56 (1993). Reviews: J. Trinick, Trends Biochem. Sci. 19, 405-409 (1994); K. Maruyama, Biophys. Chem. 50, 73-85 (1994). |