Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP
dc.contributor.author | Frado, Ling-Ling Young | |
dc.contributor.author | Craig, Roger W. | |
dc.date | 2022-08-11T08:10:05.000 | |
dc.date.accessioned | 2022-08-23T16:55:05Z | |
dc.date.available | 2022-08-23T16:55:05Z | |
dc.date.issued | 1989-08-01 | |
dc.date.submitted | 2008-10-31 | |
dc.identifier.citation | J Cell Biol. 1989 Aug;109(2):529-38. | |
dc.identifier.issn | 0021-9525 (Print) | |
dc.identifier.pmid | 2760106 | |
dc.identifier.uri | http://hdl.handle.net/20.500.14038/42639 | |
dc.description.abstract | We have used electron microscopy and proteolytic susceptibility to study the structural basis of myosin-linked regulation in synthetic filaments of scallop striated muscle myosin. Using papain as a probe of the structure of the head-rod junction, we find that this region of myosin is approximately five times more susceptible to proteolytic attack under activating (ATP/high Ca2+) or rigor (no ATP) conditions than under relaxing conditions (ATP/low Ca2+). A similar result was obtained with native myosin filaments in a crude homogenate of scallop muscle. Proteolytic susceptibility under conditions in which ADP or adenosine 5'-(beta, gamma-imidotriphosphate) (AMPPNP) replaced ATP was similar to that in the absence of nucleotide. Synthetic myosin filaments negatively stained under relaxing conditions showed a compact structure, in which the myosin cross-bridges were close to the filament backbone and well ordered, with a clear 14.5-nm axial repeat. Under activating or rigor conditions, the cross-bridges became clumped and disordered and frequently projected further from the filament backbone, as has been found with native filaments; when ADP or AMPPNP replaced ATP, the cross-bridges were also disordered. We conclude (a) that Ca2+ and ATP affect the affinity of the myosin cross-bridges for the filament backbone or for each other; (b) that the changes observed in the myosin filaments reflect a property of the myosin molecules alone, and are unlikely to be an artifact of negative staining; and (c) that the ordered structure occurs only in the relaxed state, requiring both the presence of hydrolyzed ATP on the myosin heads and the absence of Ca2+. | |
dc.language.iso | en_US | |
dc.relation | <a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=2760106&dopt=Abstract">Link to Article in PubMed</a> | |
dc.subject | Actins | |
dc.subject | Adenosine Triphosphate | |
dc.subject | Animals | |
dc.subject | Calcium | |
dc.subject | Cytoskeleton | |
dc.subject | Microfilaments | |
dc.subject | Microscopy, Electron | |
dc.subject | Molecular Structure | |
dc.subject | Mollusca | |
dc.subject | Myosins | |
dc.subject | Papain | |
dc.subject | Cell Biology | |
dc.title | Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP | |
dc.type | Journal Article | |
dc.source.journaltitle | The Journal of cell biology | |
dc.source.volume | 109 | |
dc.source.issue | 2 | |
dc.identifier.legacyfulltext | https://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=1968&context=oapubs&unstamped=1 | |
dc.identifier.legacycoverpage | https://escholarship.umassmed.edu/oapubs/969 | |
dc.identifier.contextkey | 659151 | |
refterms.dateFOA | 2022-08-23T16:55:05Z | |
html.description.abstract | <p>We have used electron microscopy and proteolytic susceptibility to study the structural basis of myosin-linked regulation in synthetic filaments of scallop striated muscle myosin. Using papain as a probe of the structure of the head-rod junction, we find that this region of myosin is approximately five times more susceptible to proteolytic attack under activating (ATP/high Ca2+) or rigor (no ATP) conditions than under relaxing conditions (ATP/low Ca2+). A similar result was obtained with native myosin filaments in a crude homogenate of scallop muscle. Proteolytic susceptibility under conditions in which ADP or adenosine 5'-(beta, gamma-imidotriphosphate) (AMPPNP) replaced ATP was similar to that in the absence of nucleotide. Synthetic myosin filaments negatively stained under relaxing conditions showed a compact structure, in which the myosin cross-bridges were close to the filament backbone and well ordered, with a clear 14.5-nm axial repeat. Under activating or rigor conditions, the cross-bridges became clumped and disordered and frequently projected further from the filament backbone, as has been found with native filaments; when ADP or AMPPNP replaced ATP, the cross-bridges were also disordered. We conclude (a) that Ca2+ and ATP affect the affinity of the myosin cross-bridges for the filament backbone or for each other; (b) that the changes observed in the myosin filaments reflect a property of the myosin molecules alone, and are unlikely to be an artifact of negative staining; and (c) that the ordered structure occurs only in the relaxed state, requiring both the presence of hydrolyzed ATP on the myosin heads and the absence of Ca2+.</p> | |
dc.identifier.submissionpath | oapubs/969 | |
dc.contributor.department | Department of Cell Biology | |
dc.source.pages | 529-38 |