Monday, April 27, 2015

Supplier Focus: AAT Bioquest – Phalloidin and Phalloidin Conjugates for Staining Actin Filaments

Actin is a globular, roughly 42-kDa protein found in almost all eukaryotic cells. It is also one of the most highly conserved proteins, differing by no more than 20% in species as diverse as algae and humans. Actin is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. Thus, actin participates in many important cellular processes including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, as well as the establishment and maintenance of cell junctions and cell shape.

AAT Bioquest’s phalloidin conjugates selectively binds to F-actins. Used at nanomolar concentrations, phalloidin derivatives are convenient probes for labeling, identifying and quantitating F-actins in formaldehyde-fixed and permeabilized tissue sections, cell cultures or cell-free experiments. Phalloidin binds to actin filaments much more tightly than to actin monomers, leading to a decrease in the rate constant for the dissociation of actin subunits from filament ends, essentially stabilizing actin filaments through the prevention of filament depolymerization. Moreover, phalloidin is found to inhibit the ATP hydrolysis activity of F-actin. Phalloidin functions differently at various concentrations in cells. When introduced into the cytoplasm at low concentrations, phalloidin recruits the less polymerized forms of cytoplasmic actin as well as filamin into stable “islands” of aggregated actin polymers, yet it does not interfere with stress fibers, i.e. thick bundles of microfilaments. The property of phalloidin is a useful tool for investigating the distribution of F-actin in cells by labeling phalloidin with fluorescent analogs and using them to stain actin filaments for light microscopy. Fluorescent derivatives of phalloidin have turned out to be enormously useful in localizing actin filaments in living or fixed cells as well as for visualizing individual actin filaments in vitro. Fluorescent phalloidin derivatives have been used as an important tool in the study of actin networks at high resolution. AAT Bioquest offers a variety of fluorescent phalloidin derivatives with different colors for multicolor imaging applications as summarized in the following table.

Current Range

Catalogue No. Product Name Unit MW Ex (nm) Em (nm)
5301-AAT Phalloidin 1 mg 788.88 N/A N/A
5302-AAT Phalloidin Amine 100 μg 901.91 N/A N/A
23100-AAT Phalloidin-AMCA Conjugate 300 tests ~1000 353 442
23101-AAT Phalloidin-Fluorescein Conjugate 300 tests ~1100 492 518
23102-AAT Phalloidin-Tetramethylrhodamine Conjugate 300 tests ~1200 546 575
23103-AAT Phalloidin-California Red Conjugate* 300 tests ~1000 583 605
23110-AAT Phalloidin-iFluor™ 350 Conjugate 300 tests ~1000 353 442
23111-AAT Phalloidin-iFluor™ 405 Conjugate 300 tests ~1400 400 421
23115-AAT Phalloidin-iFluor™ 488 Conjugate 300 tests ~1900 493 517
23116-AAT Phalloidin-iFluor™ 514 Conjugate 300 tests ~1800 520 547
23117-AAT Phalloidin-iFluor™ 532 Conjugate 300 tests ~1800 542 558
23119-AAT Phalloidin-iFluor™ 555 Conjugate 300 tests ~1300 556 574
23122-AAT Phalloidin-iFluor™ 594 Conjugate 300 tests ~1600 590 618
23125-AAT Phalloidin-iFluor™ 633 Conjugate 300 tests ~2100 634 649
23127-AAT Phalloidin-iFluor™ 647 Conjugate 300 tests ~2200 650 665
23128-AAT Phalloidin-iFluor™ 680 Conjugate 300 tests ~2700 681 698
23129-AAT Phalloidin-iFluor™ 700 Conjugate 300 tests ~3000 692 708
23130-AAT Phalloidin-iFluor™ 750 Conjugate 300 tests ~3300 752 778
23131-AAT Phalloidin-iFluor™ 790 Conjugate 300 tests ~2800 787 808

*Excellent replacement to Texas Red-phalloidin conjugate due to their essentially identical spectral properties.


  1. Szczesna D, Lehrer SS (1993). The binding of fluorescent phallotoxins to actin in myofibrils. J Muscle Res Cell Motil, 14(6), 594.
  2. Johnson S C, Nancy M. McKenna M N, and Wang Y (1988). Association of microinjected myosin and its subfragments with myofibrils in living muscle cells. J Cell Biol, 107(6), 2213.
  3. Wang K, Feramisco JR, Ash JF (1982). Fluorescent localization of contractile proteins in tissue culture cells. Methods Enzymol, 85 Pt B, 514.
  4. Miki M, Barden JA, dos Remedios CG, Phillips L, Hambly BD (1987). Interaction of phalloidin with chemically modified actin. Eur J Biochem 165, 125.
    Cooper JA. (1987). Effects of cytochalasin and phalloidin on actin. J Cell Biol 105, 1473.

Where can I find more information about AAT Bioquest?

Visit the manufacturer page at, email or call +44 (0) 1638 782600.

Stratech Scientific is a distributor of high quality, competitively priced, reliable products for research laboratories throughout the UK and Europe. Please contact us to find out which ranges we can supply in your country.
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