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dc.contributor.authorZhu, Tong
dc.contributor.authorBeckingham, Kathleen M.
dc.contributor.authorIkebe, Mitsuo
dc.date2022-08-11T08:10:04.000
dc.date.accessioned2022-08-23T16:54:07Z
dc.date.available2022-08-23T16:54:07Z
dc.date.issued1998-08-01
dc.date.submitted2008-08-04
dc.identifier.citation<p>J Biol Chem. 1998 Aug 7;273(32):20481-6.</p>
dc.identifier.issn0021-9258 (Print)
dc.identifier.doi10.1074/jbc.273.32.20481
dc.identifier.pmid9685403
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42427
dc.description.abstractWe coexpressed myosin Ibeta heavy chain with three different calmodulin mutants in which the two Ca2+-binding sites of the two N-terminal domain (E12Q), C-terminal domain (E34Q), or all four sites (E1234Q) are mutated in order to define the importance of these Ca2+ binding sites to the regulation of myosin Ibeta. The calmodulin mutated at the two Ca2+ binding sites in N-terminal domain and C-terminal domain lost its lower affinity Ca2+ binding site and higher affinity Ca2+ binding site, respectively. We found that, based upon the change in the actin-activated ATPase activities and actin translocating activities, myosin Ibeta with E12Q calmodulin has the regulatory characteristics similar to myosin Ibeta containing wild-type calmodulin, while myosin Ibeta with E34Q or E1234Q calmodulin lose all Ca2+ regulation. While the increase in myosin Ibeta ATPase activity paralleled the dissociation of 1 mol of calmodulin from myosin Ibeta heavy chain for both wild type (above pCa 5) and E12Q calmodulin (above pCa 6), the Ca2+ level required for the inhibition of actin-translocating activity of myosin Ibeta was lower than that required for dissociation of calmodulin, suggesting that the conformational change induced by the binding of Ca2+ at the high affinity site but not the dissociation of calmodulin is critical for the inhibition of the motor activity. Our results suggest that the regulation of unconventional myosins by Ca2+ is directly mediated by the Ca2+ binding to calmodulin, and that the C-terminal pair of Ca2+-binding sites are critical for this regulation.
dc.language.isoen_US
dc.relation<p><a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=9685403&dopt=Abstract">Link to Article in PubMed</a></p>
dc.relation.urlhttps://doi.org/10.1074/jbc.273.32.20481
dc.subjectActins
dc.subjectAdenosine Triphosphatases
dc.subjectAnimals
dc.subjectBinding Sites
dc.subjectCalcium
dc.subjectCalcium-Binding Proteins
dc.subjectCalmodulin
dc.subjectCalmodulin-Binding Proteins
dc.subjectCattle
dc.subjectModels, Molecular
dc.subjectMutation
dc.subjectMyosin Heavy Chains
dc.subjectProtein Binding
dc.subjectProtein Conformation
dc.subjectRecombinant Proteins
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleHigh affinity Ca2+ binding sites of calmodulin are critical for the regulation of myosin Ibeta motor function
dc.typeArticle
dc.source.journaltitleThe Journal of biological chemistry
dc.source.volume273
dc.source.issue32
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/778
dc.identifier.contextkey564693
html.description.abstract<p>We coexpressed myosin Ibeta heavy chain with three different calmodulin mutants in which the two Ca2+-binding sites of the two N-terminal domain (E12Q), C-terminal domain (E34Q), or all four sites (E1234Q) are mutated in order to define the importance of these Ca2+ binding sites to the regulation of myosin Ibeta. The calmodulin mutated at the two Ca2+ binding sites in N-terminal domain and C-terminal domain lost its lower affinity Ca2+ binding site and higher affinity Ca2+ binding site, respectively. We found that, based upon the change in the actin-activated ATPase activities and actin translocating activities, myosin Ibeta with E12Q calmodulin has the regulatory characteristics similar to myosin Ibeta containing wild-type calmodulin, while myosin Ibeta with E34Q or E1234Q calmodulin lose all Ca2+ regulation. While the increase in myosin Ibeta ATPase activity paralleled the dissociation of 1 mol of calmodulin from myosin Ibeta heavy chain for both wild type (above pCa 5) and E12Q calmodulin (above pCa 6), the Ca2+ level required for the inhibition of actin-translocating activity of myosin Ibeta was lower than that required for dissociation of calmodulin, suggesting that the conformational change induced by the binding of Ca2+ at the high affinity site but not the dissociation of calmodulin is critical for the inhibition of the motor activity. Our results suggest that the regulation of unconventional myosins by Ca2+ is directly mediated by the Ca2+ binding to calmodulin, and that the C-terminal pair of Ca2+-binding sites are critical for this regulation.</p>
dc.identifier.submissionpathoapubs/778
dc.contributor.departmentDepartment of Physiology
dc.source.pages20481-6


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