What are effects of cytochalasin D and phalloidin on actin filaments?
Cytochalasin D binds to the + end of F-actin and prevents further addition of G actin. Phalloidin is from the poisonous mushroom (Amanita (angel of death)). It prevents actin filaments from depolymerizing. Eating quantities of raw meat may be used to treat this form of poisoning because of its high content of actin that binds to the phalloidin. Phalloidin is also used to detect actin filaments cytochemically. How does profilin promote actin assembly? Profilin stimulates assembly of actin filaments. It can complex with G-actin and attract more monomers to the + end. Thus, it may speed up the nucleation process. It may interact with membrane components in cell-cell signaling and reduce inhibitors. Or, it may be a messenger from a signalling pathway that stimulates polymerization of actin in response to a cell stimulus. It also can act as a nucleotide exchange factor, recharging the ADP actin monomers with ATP. What are roles for severing proteins (gelsolin and cofilin) in cell motility?
