Interaction of Phalloidin with Actin

Abstract

Phalloidin, a toxic bicyclic peptide of rapid action from the toadstool, Amanita phalloides, gives rise to polymerization of G-actin to filamentous structures (Ph-actin) in a medium of low ionic strength. Ph-actin closely resembles the microfilaments found in liver membrane fractions (Ph-filaments) after in vivo or in vitro poisoning. Both phalloidin induced filaments are resistant to 0.6 M KI in contrast to F-actin, and become decorated by heavy meromyosin. After preincubation with cytochalasin B significantly fewer actin filaments are observed.