Ca2+ and Ionic Strength Dependencies of S1-ADP Binding to Actin-Tropomyosin-Troponin: Regulatory Implications

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dc.contributor.authorGafurov, Borisen_US
dc.contributor.authorChen, Yi-Deren_US
dc.contributor.authorChalovich, Josephen_US
dc.date.accessioned2011-03-02T15:53:06Zen_US
dc.date.accessioned2011-05-17T01:27:01Z
dc.date.available2011-03-02T15:53:06Zen_US
dc.date.available2011-05-17T01:27:01Z
dc.date.issued2004-09en_US
dc.description.abstractSkeletal and cardiac muscle contraction are inhibited by the actin-associated complex of tropomyosin-troponin. Binding of Ca21 to troponin or binding of ATP-free myosin to actin reverses this inhibition. Ca21 and ATP-free myosin stabilize different tropomyosin-actin structural arrangements. The position of tropomyosin on actin affects the binding of ATP-free myosin to actin but does not greatly affect myosin-ATP binding. Ca21 and ATP-free myosin alter both the affinity of ATP-free myosin for actin and the kinetics of that binding. A parallel pathway model of regulation simulated the effects of Ca21 and ATP-free myosin binding on both equilibrium binding of myosin-nucleotide complexes to actin and the general features of ATPase activity. That model was recently shown to simulate the kinetics of myosin-S1 binding but the analysis was limited to a single condition because of the limited data available. We have now measured equilibrium binding and binding kinetics of myosin-S1-ADP to actin at a series of ionic strengths and free Ca21 concentrations. The parallel pathway model of regulation is consistent with those data. In that model the interaction between adjacent regulatory complexes fully saturated with Ca21 was destabilized and the inactive state of actin was stabilized at high ionic strength. These changes explain the previously observed change in binding kinetics with increasing ionic strength. Originally published Biophysical Journal, Vol. 87, No. 3, Sep 2004en_US
dc.identifier.citationBiophysical Journal; 87:3 p. 1825-1835en_US
dc.identifier.doi10.1529/biophysj.104.043364
dc.identifier.pmidPMC1304587en_US
dc.identifier.urihttp://hdl.handle.net/10342/3284en_US
dc.language.isoen_USen_US
dc.publisherEast Carolina Universityen_US
dc.relation.urihttp://www.cell.com/biophysj/retrieve/pii/S0006349504736632en_US
dc.rightsAuthor notified of opt-out rights by Cammie Jennings.en_US
dc.subjectMyosin-S1-ADPen_US
dc.subjectActin bindingen_US
dc.subjectParallel pathway regulationen_US
dc.titleCa2+ and Ionic Strength Dependencies of S1-ADP Binding to Actin-Tropomyosin-Troponin: Regulatory Implicationsen_US
dc.typeArticleen_US
ecu.journal.issue3
ecu.journal.nameBiophysical Journal
ecu.journal.pages1825-1835
ecu.journal.volume87

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