Phalloidin and phallacidin are collectively called phallotoxins, which are bicyclic peptides isolated from the deadly Amanita phalloides mushroom. Phallotoxins bind specifically to F-actin filaments with high affinity (1). Fluorescently labeled phallotoxins are very useful tool for investigating the distribution of F-actin. Labeled phallotoxins have similar affinity for both large and small filaments, binding in a stoichiometric ratio of about one phalloidin molecule per actin subunit in muscle and non-muscle cells from various species of plants and animals. Phallotoxins shift the F-actin monomer/polymer equilibrium toward the polymer, lowering the critical concentration for polymerization up to 30-fold (3,4). Phallotoxins also stabilize F-actin filaments, inhibiting depolymerization by cytochalasins, potassium iodide and elevated temperatures. Moreover, phallotoxin-labeled actin filaments remain functional; labeled glycerinated muscle fibers still contract, and labeled actin filaments still move on solid-phase myosin substrates (5,6). Fluorescent phallotoxins can also be used to quantify the amount of F-actin in cells (7,8). Biotin-XX phalloidin stains F-actin with nanomolar affinity. The long flexible spacer group XX facilitates interaction between biotin and avidin or streptavidin which can be labeled with a fluorophore or an enzyme for visualization of F-actin. Biotin-XX phalloidin can also be used for detecting F-actin by electron microscopy. The content in each vial (100 U) is sufficient to stain ~100 samples with 200 uL staining volume per sample.
- White lyophilized solid soluble in methanol
- Store at -20°C
- MW: 1240