5MVA
Structure of the thin filament at high calcium concentration
Summary for 5MVA
| Entry DOI | 10.2210/pdb5mva/pdb |
| EMDB information | 3576 |
| Descriptor | Actin, alpha skeletal muscle, ADENOSINE-5'-DIPHOSPHATE (2 entities in total) |
| Functional Keywords | thin filament, troponin, actin, tropomyosin, structural protein |
| Biological source | Oryctolagus cuniculus (Rabbit) |
| Cellular location | Cytoplasm, cytoskeleton: P68135 |
| Total number of polymer chains | 23 |
| Total formula weight | 972965.18 |
| Authors | Paul, D.M.,Squire, J.M.,Morris, E.P. (deposition date: 2017-01-16, release date: 2017-11-29, Last modification date: 2025-04-09) |
| Primary citation | Paul, D.M.,Squire, J.M.,Morris, E.P. Relaxed and active thin filament structures; a new structural basis for the regulatory mechanism. J. Struct. Biol., 197:365-371, 2017 Cited by PubMed Abstract: The structures of muscle thin filaments reconstituted using skeletal actin and cardiac troponin and tropomyosin have been determined with and without bound Ca using electron microscopy and reference-free single particle analysis. The resulting density maps have been fitted with atomic models of actin, tropomyosin and troponin showing that: (i) the polarity of the troponin complex is consistent with our 2009 findings, with large shape changes in troponin between the two states; (ii) without Ca the tropomyosin pseudo-repeats all lie at almost equivalent positions in the 'blocked' position on actin (over subdomains 1 and 2); (iii) in the active state the tropomyosin pseudo-repeats are all displaced towards subdomains 3 and 4 of actin, but the extent of displacement varies within the regulatory unit depending upon the axial location of the pseudo-repeats with respect to troponin. Individual pseudo-repeats with Ca bound to troponin can be assigned either to the 'closed' state, a partly activated conformation, or the 'M-state', a fully activated conformation which has previously been thought to occur only when myosin heads bind. These results lead to a modified view of the steric blocking model of thin filament regulation in which cooperative activation is governed by troponin-mediated local interactions of the pseudo-repeats of tropomyosin with actin. PubMed: 28161413DOI: 10.1016/j.jsb.2017.01.004 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (27.7 Å) |
Structure validation
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