title: Ca2+-dependent regulation of the dynamic polarity of F-actin under the influence of tropomyosin and troponin.
abstract: A novel method that we have developed in the preceding paper to study the subunit exchange rates of F-actin (N. Suzuki and K. Mihashi, Biophys. Chem. 33 (1989) 177) was applied to regulated F-actin (a complex of F-actin, tropomyosin and troponin). We found that the dynamic polarity of regulated F-actin is modulated in a Ca2+-dependent manner, giving rise to strong suppression of the on/off rates of subunit exchange at the P-end. We interpreted this characteristic suppression as follows. Removal of Ca2+ from troponin C in regulated F-actin produces strong constraints on fluctuations in potential energy of an intermediate conformation of the terminal structure (P-end) which would be formed in the course of association and dissociation of the actin subunit.
authors.affiliation: Department of Physics, Faculty of Science, Nagoya University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mihashi
authors.forename: N
authors.initials: N
authors.lastname: Suzuki
authors.forename: A
authors.initials: A
authors.lastname: Ooi
mesh_terms: D000199:Actins / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D007700:Kinetics; D046911:Macromolecular Substances; D008433:Mathematics; D008962:Models, Theoretical; D014335:Tropomyosin / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*
chemical_list: D000199:Actins; D046911:Macromolecular Substances; D014335:Tropomyosin; D014336:Troponin; D002118:Calcium