Show simple item record

dc.contributor.authorCraig, Roger W.
dc.contributor.authorPadrón, Raúl
dc.contributor.authorKendrick-Jones, John
dc.date2022-08-11T08:10:05.000
dc.date.accessioned2022-08-23T16:55:06Z
dc.date.available2022-08-23T16:55:06Z
dc.date.issued1987-09-01
dc.date.submitted2008-10-31
dc.identifier.citationJ Cell Biol. 1987 Sep;105(3):1319-27.
dc.identifier.issn0021-9525 (Print)
dc.identifier.pmid2958483
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42644
dc.description.abstractElectron microscopy has been used to study the structural changes that occur in the myosin filaments of tarantula striated muscle when they are phosphorylated. Myosin filaments in muscle homogenates maintained in relaxing conditions (ATP, EGTA) are found to have nonphosphorylated regulatory light chains as shown by urea/glycerol gel electrophoresis and [32P]phosphate autoradiography. Negative staining reveals an ordered, helical arrangement of crossbridges in these filaments, in which the heads from axially neighboring myosin molecules appear to interact with each other. When the free Ca2+ concentration in a homogenate is raised to 10(-4) M, or when a Ca2+-insensitive myosin light chain kinase is added at low Ca2+ (10(-8) M), the regulatory light chains of myosin become rapidly phosphorylated. Phosphorylation is accompanied by potentiation of the actin activation of the myosin Mg-ATPase activity and by loss of order of the helical crossbridge arrangement characteristic of the relaxed filament. We suggest that in the relaxed state, when the regulatory light chains are not phosphorylated, the myosin heads are held down on the filament backbone by head-head interactions or by interactions of the heads with the filament backbone. Phosphorylation of the light chains may alter these interactions so that the crossbridges become more loosely associated with the filament backbone giving rise to the observed changes and facilitating crossbridge interaction with actin.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=2958483&dopt=Abstract">Link to Article in PubMed</a>
dc.subjectAnimals
dc.subjectCa(2+) Mg(2+)-ATPase
dc.subjectMicrofilaments
dc.subjectMicroscopy, Electron
dc.subjectMuscles
dc.subjectMyosin-Light-Chain Kinase
dc.subjectMyosins
dc.subjectPhosphorylation
dc.subjectSpiders
dc.subjectAnatomy
dc.subjectCell Biology
dc.subjectMusculoskeletal System
dc.titleStructural changes accompanying phosphorylation of tarantula muscle myosin filaments
dc.typeJournal Article
dc.source.journaltitleThe Journal of cell biology
dc.source.volume105
dc.source.issue3
dc.identifier.legacyfulltexthttps://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=1972&amp;context=oapubs&amp;unstamped=1
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/973
dc.identifier.contextkey659155
refterms.dateFOA2022-08-23T16:55:06Z
html.description.abstract<p>Electron microscopy has been used to study the structural changes that occur in the myosin filaments of tarantula striated muscle when they are phosphorylated. Myosin filaments in muscle homogenates maintained in relaxing conditions (ATP, EGTA) are found to have nonphosphorylated regulatory light chains as shown by urea/glycerol gel electrophoresis and [32P]phosphate autoradiography. Negative staining reveals an ordered, helical arrangement of crossbridges in these filaments, in which the heads from axially neighboring myosin molecules appear to interact with each other. When the free Ca2+ concentration in a homogenate is raised to 10(-4) M, or when a Ca2+-insensitive myosin light chain kinase is added at low Ca2+ (10(-8) M), the regulatory light chains of myosin become rapidly phosphorylated. Phosphorylation is accompanied by potentiation of the actin activation of the myosin Mg-ATPase activity and by loss of order of the helical crossbridge arrangement characteristic of the relaxed filament. We suggest that in the relaxed state, when the regulatory light chains are not phosphorylated, the myosin heads are held down on the filament backbone by head-head interactions or by interactions of the heads with the filament backbone. Phosphorylation of the light chains may alter these interactions so that the crossbridges become more loosely associated with the filament backbone giving rise to the observed changes and facilitating crossbridge interaction with actin.</p>
dc.identifier.submissionpathoapubs/973
dc.contributor.departmentDepartment of Anatomy
dc.source.pages1319-27


Files in this item

Thumbnail
Name:
2958483.pdf
Size:
3.143Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record