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). Fluorescein phalloidin stains F-actin with nanomolar affinity. Fluorescent phalloidin conjugates are typically used to stain fixed and permeabilized cells (1-3), but can also be loaded into live cells via cationic liposomes. Green fluorescent rhodamine 110 phalloidin has good photostability and is a superior substitute for fluorescein phalloidin. Also see the next generation CF™ dye phalloidin conjugates, which have superior brightness and photostability. Each vial (300 U) contains sufficient probe for staining ~300 samples with a staining volume of 200 uL per sample.
- λEx/λ Em(MeOH) = 502/524nm
- Light yellow solid soluble in MeOH
- Store at -20°C and protect from light