Cytochalasin B and the structure of actin gels. II. Further evidence for the splitting of F-actin by cytochalasin B.
Cytochalasin B decreased the flow birefringence and s20,w and increased the extinction angle of actin filaments in salt solutions favoring polymerization of the protein. These changes occurred without a detectable increase in the equilibrium actin monomer concentration determined by a radioassay. These results complement earlier observations indicating that cytochalasin B shortens actin filaments without net depolymerization. Analyzed in terms of Flory's classical network theory, this shortening accounts for the marked effect of cytochalasin B in dissolving the gel structure of F-actin crosslinked by actin-binding protein concentrations near the critical concentration for incipient gelation. Cytochalasin B decreased the annealing rate of low concentrations of actin filament fragments prepared by sonic disruption. The result is consistent with the idea that cytochalasin B binds to the ends of actin filaments, and may explain how cytochalasin B causes filament shortening.
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D003571:Cytochalasin B / Q000494:pharmacology*; D003599:Cytoskeleton / Q000187:drug effects; D066298:In Vitro Techniques; D011108:Polymers / Q000378:metabolism; D011817:Rabbits
D000199:Actins; D011108:Polymers; D003571:Cytochalasin B