Cytochalasin D is a member of the class of mycotoxins known as cytochalasins. Cytochalasin D is an alkaloid produced by Helminthosporium and other molds. Cytochalasin D is a cell-permeable and potent inhibitor of actin polymerization. It disrupts actin microfilaments and activates the p53-dependent pathways causing arrest of the cell cycle at the G1-S transition. It is believed to bind to F-actin polymer and prevent polymerization of actin monomers. Studies done with cytochalasin D (CD) have found that the formation of CD-actin dimers, contain ATP-bound actin. These CD-actin dimers are reduced to CD-actin monomers as a result of ATP hydrolysis. The resulting CD-actin monomer can bind ATP-actin monomer to reform the CD-actin dimer. CD is very effective; only low concentrations (0.2 μM) are needed to prevent membrane ruffling and disrupt treadmilling.
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