Titin is an extraordinarily long, flexible, and slender myofibrillar protein.
نویسندگان
چکیده
" Titin " is a term used to describe a pair of closely related megadalton polypeptides that together are the third most abundant myofibrillar protein in a wide range of striated muscles. It has been proposed that titin and another giant protein, nebulin , are the major components of an elastic cytoskeletal lattice within the sarcomere. We have now purified the leading band, titin -2 (T2), of the titin doublet in native forms by extraction with Guba -Straub solution followed by chromatography. Electron microscopy of low-angle-shadowed and negatively stained specimens revealed that T2 chains self-assembled into extremely long (from 0.1 micron to over 1.0 micron), flexible, and extensible slender strands (4-5 nm in diameter) with axial periodicity. Furthermore, these strands tended to associate to form filamentous bundles and meshworks. Thus, titin appears to be ideally suited as a component of an elastic lattice that serves as an organizing scaffold or template for thick and thin filaments.
منابع مشابه
Molecular characterization of avian muscle titin.
Titin is an approximately 3000-kDa polypeptide that constitutes a set of elastic filaments that connect thick filaments to the Z-line in vertebrate striated muscle myofibrils. To characterize the primary structure of titin, three overlapping cDNA clones comprising 2.4 kilobases of avian muscle titin coding sequence were obtained from a cDNA library constructed from embryonic chick cardiac muscl...
متن کاملSymposium: Meat Science and Muscle Biology: Postmortem Changes in Myofibrillar Protein and the Associated Contribution to Meat Quality
Myofibrillar proteins make up the largest amount of muscle protein and they are largely responsible for postmortem changes in rigor mortis, tenderness and water holding capacity. The changes of myofibrillar proteins and the mechanism of these changes in the tenderization process have received much attention. Proteolysis has long been thought of as the mechanism of postmortem tenderization. The ...
متن کاملTitin: major myofibrillar components of striated muscle.
Electrophoretic analyses of protein components of striated muscle myofibril purified from various vertebrate and invertebrate species revealed that proteins much larger than myosin heavy chain are present in significant amounts. To define possible roles of these heretofore unidentified proteins, we purified a combination of two uncommonly large proteins, designated as titin, from chicken breast...
متن کاملThe giant protein titin: a regulatory node that integrates myocyte signaling pathways.
Titin, the largest protein in the human body, is well known as a molecular spring in muscle cells and scaffold protein aiding myofibrillar assembly. However, recent evidence has established another important role for titin: that of a regulatory node integrating, and perhaps coordinating, diverse signaling pathways, particularly in cardiomyocytes. We review key findings within this emerging fiel...
متن کاملEffects of different enzymic treatments on the release of titin fragments from rabbit skeletal myofibrils. Purification of an 800 kDa titin polypeptide.
In myofibrils, titin (also called connectin) molecules span from Z line to M line and constitute a third filament system containing an elastic domain in the I band. This giant protein is particularly sensitive to proteolysis in situ. Treatment of rabbit skeletal myofibrils with exogenous proteinases induces a release of titin fragments, which are detected in the soluble myofibrillar fraction. T...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 81 12 شماره
صفحات -
تاریخ انتشار 1984