Calcium-dependent interaction of actin filaments with actin binding protein in the presence of calmodulin and caldesmon.
Caldesmon, calmodulin-, and actin-binding protein of chicken gizzard did not affect the process of polymerization of actin induced by 0.1 M KCl. Caldesmon binds to F-actin, thus inhibiting the gelation action of actin binding protein (ABP; filamin). Low shear viscosity and flow birefringence measurements revealed that in a system of calmodulin, caldesmon, ABP, and F-actin, gelation occurs in the presence of micromolar Ca2+ concentrations, but not in the absence of Ca2+. Electron microscopic observations showed the Ca2+-dependent formation of actin bundles in this system. These results were interpreted by the flip-flop mechanism: in the presence of Ca2+, a calmodulin-caldesmon complex is released from actin filaments on which ABP exerts its gelating action. On the other hand, in the absence of Ca2+, caldesmon remains bound to actin filaments, thus preventing the action of ABP.
Maruyama
K
K
Morimoto
K
K
Kijima
Y
Y
Sobue
K
K
Kakiuchi
S
S
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins / Q000378:metabolism*; D002645:Chickens; D005782:Gels; D018260:Gelsolin; D005895:Gizzard, Avian; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*
D000199:Actins; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D005782:Gels; D018260:Gelsolin; D046911:Macromolecular Substances; D008840:Microfilament Proteins; C016953:brevin; D010749:Phosphoprotein Phosphatases; D002118:Calcium