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Tropomodulin is associated with the free (pointed) ends of the thin filaments in rat skeletal muscle
| Content Provider | Semantic Scholar |
|---|---|
| Author | Fowler, Velia M. Sussmann, Melissa Miller, Peter G. Flucher, Bernhard E. |
| Copyright Year | 1993 |
| Abstract | The length and spatial organization of thin filaments in skeletal muscle sarcomeres are precisely maintained and are essential for efficient muscle contraction. While the major structural components of skeletal muscle sarcomeres have been well characterized, the mechanisms that regulate thin filament length and spatial organization are not well understood. Tropomodulin is a new, 40.6-kD tropomyosin-binding protein from the human erythrocyte membrane skeleton that binds to one end of erythrocyte tropomyosin and blocks head-to-tail association of tropomyosin molecules along actin filaments. Here we show that rat psoas skeletal muscle contains tropomodulin based on immunoreactivity, identical apparent mobility on SDS gels, and ability to bind muscle tropomyosin. Results from immunofluorescence labeling of isolated myofibrils at resting and stretched lengths using anti-erythrocyte tropomodulin antibodies indicate that tropomodulin is localized at or near the free (pointed) ends of the thin filaments; this localization is not dependent on the presence of myosin thick filaments. Immunoblotting of supernatants and pellets obtained after extraction of myosin from myofibrils also indicates that tropomodulin remains associated with the thin filaments. 1.2-1.6 copies of muscle tropomodulin are present per thin filament in myofibrils, supporting the possibility that one or two tropomodulin molecules may be associated with the two terminal tropomyosin molecules at the pointed end of each thin filament. Although a number of proteins are associated with the barbed ends of the thin filaments at the Z disc, tropomodulin is the first protein to be specifically located at or near the pointed ends of the thin filaments. We propose that tropomodulin may cap the tropomyosin polymers at the pointed end of the thin filament and play a role in regulating thin filament length. |
| Starting Page | 411 |
| Ending Page | 420 |
| Page Count | 10 |
| File Format | PDF HTM / HTML |
| PubMed reference number | 8421055 |
| Volume Number | 120 |
| Journal | The Journal of cell biology |
| Alternate Webpage(s) | http://jcb.rupress.org/content/jcb/120/2/411.full.pdf |
| Alternate Webpage(s) | http://ftp.ncbi.nlm.nih.gov/pub/pmc/d0/9c/jc1202411.PMC2119515.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Actin myofilament Copy (object) Cytoskeletal Filaments Erythrocyte Membrane Erythrocytes Gel Immunofluorescence assay Microfilaments Muscle Contraction Myalgia Oral Pellet Rest Sarcomeres Skeletal muscle structure TMOD1 gene Tropomyosin |
| Content Type | Text |
| Resource Type | Article |
