Polylysine was found to induce polymerization of muscle actin in a low ionic strength buffer containing 0.4 mM MgCl2. The rate of induced polymerization was dependent on the amount and on the molecular size of the polylysine added. A similar effect was obtained by adding actin nuclei (containing about 2-4 actin subunits) cross-linked by p-N,N'-phenylenebismaleimide to G-actin under the same conditions, suggesting that the effect of polylysine is due to promotion of the formation of actin nuclei. Polymerization induced by polylysine and by cross-linked actin nuclei was inhibited by low concentrations (10(-8)-10(-6)M) of cytochalasins. Binding experiments showed that actin filaments, but not actin monomers, contained high-affinity binding sites for [3H]cytochalasin B (one site per 600 actin monomers). The relative affinity of several cytochalasins for these sites (determined by competitive displacement of [3H]dihydrocytochalasin B) was: cytochalasin D greater than cytochalasin E approximately equal to dihydrocytochalasin B. The results of this study suggest that cytochalasins inhibit nuclei-induced actin polymerization by binding to highly specific sites at the point of monomer addition, i.e., the elongation site, in actin nuclei and filaments.
Article| February 01 1980
Cytochalasins inhibit nuclei-induced actin polymerization by blocking filament elongation.
D C Lin
K D Tobin
Online ISSN: 1540-8140
Print ISSN: 0021-9525
J Cell Biol (1980) 84 (2): 455–460.
D C Lin, K D Tobin, M Grumet, S Lin; Cytochalasins inhibit nuclei-induced actin polymerization by blocking filament elongation.. J Cell Biol 1 February 1980; 84 (2): 455–460. doi: https://doi.org/10.1083/jcb.84.2.455
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