title: Influence of caltropin on the caldesmon induced polymerization of G-actin.
abstract: The effect of caltropin (CaT) on the caldesmon (CaD)-G-actin interaction was monitored by viscosity measurements, bioassays measuring the release of inorganic phosphate (Pi) following G-actin polymerization and fluorescence studies using acrylodan labelled G-actin. CaD induced polymerization of G-actin into filaments in the absence of salt was accompanied by an increase in relative viscosity. This effect of CaD was essentially abolished by CaT in the presence of Ca2+. In bioassays the rate of Pi release was reduced significantly in the presence of Ca2+/CaT. Acrylodan labelled G-actin when excited at 375 nm exhibited an emission maximum at 478 nm. Polymerization of G-actin resulted in shifting the emission maximum to 465 nm. When CaD was added to G-actin containing Ca2+/CaT, the rate of G-actin polymerization was reduced considerably, suggesting that CaT interferes in the CaD-G-actin interaction.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Canada.
authors.forename: R S
authors.initials: RS
authors.lastname: Mani
authors.forename: C M
authors.initials: CM
authors.lastname: Kay
mesh_terms: D000199:Actins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D002148:Calmodulin-Binding Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D018797:Cell Cycle Proteins; D002645:Chickens; D005895:Gizzard, Avian; D007700:Kinetics; D046911:Macromolecular Substances; D018482:Muscle, Skeletal / Q000378:metabolism; D009130:Muscle, Smooth; D010710:Phosphates / Q000032:analysis; D011817:Rabbits; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins; D014783:Viscosity
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; D002148:Calmodulin-Binding Proteins; D018797:Cell Cycle Proteins; D046911:Macromolecular Substances; D010710:Phosphates; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins; C489133:S100A6 protein, Gallus gallus; D000255:Adenosine Triphosphate