AAT Bioquest

Labeling Actins with iFluor™-Phalloidin Conjugates

Image of HeLa cells
Image of HeLa cells. Actin filaments were stained with iFluor® 555 phalloidin conjugate (red, Cat# 23119), and nuclei were stained with Nuclear Green™ DCS1.
Fluorescent phalloidin derivatives have been used as an important tool in studying of actin networks at high resolution. AAT Bioquest offers a variety of fluorescent phalloidin derivatives with different colors for multicolor imaging applications. 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. The property of phalloidin is useful for investigating the distribution of F-actin in cells by labeling phalloidin with fluorescent analogs and using them to stain actin filaments for fluorescence 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.

Table 1. iFluor® Phalloidin Selection Guide For Phalloidin-iFluor® Conjugates

Mol. Wt.
Ex/ Em (nm)
Filter Set
Extinction Coefficient¹
Quantum Yield
Unit Size
Phalloidin-iFluor® 350∼1300344/448DAPI20,0000.95300 Tests
Phalloidin-iFluor® 405∼1400402/425DAPI37,0000.91300 Tests
Phalloidin-iFluor® 488∼1900491/516FITC75,0000.9300 Tests
Phalloidin-iFluor® 514∼1800527/554TRITC80,0000.83300 Tests
Phalloidin-iFluor® 532∼1800543/563TRITC90,0000.68300 Tests
Phalloidin-iFluor® 555∼1300556/569TRITC100,0000.64300 Tests
Phalloidin-iFluor® 594∼1600587/603Texas Red180,0000.53300 Tests
Phalloidin-iFluor® 6331703.99638/652Texas Red250,0000.29300 Tests
Phalloidin-iFluor® 6471632.87654/669Cy5250,0000.25300 Tests
Phalloidin-iFluor® 680∼2000683/700Cy5.5220,0000.23300 Tests
Phalloidin-iFluor® 700∼3000690/713Cy5.5220,0000.23300 Tests
Phalloidin-iFluor® 750∼3300756/777Cy7275,0000.12300 Tests
Phalloidin-iFluor® 790∼2800786/811Cy7250,0000.13300 Tests