Description
Actin-Tracker Red-555 is a red fluorescent probe that specifically binds and labels filamentous actin (F-actin) in cultured cells or tissue sections.
The Actin-Tracker Red-555 probe is a Alexa Fluor 555-labeled phalloidin dye that emits red fluorescence at 565nm when excited at 555nm. Actin-Tracker Red-555 and Cy3 have similar fluorescence spectrum and can be detected using same settings under fluorescence microscopy.
Phalloidin is a polypeptide isolated from Amanita phalloides, which specifically binds F-actin in eukaryotes and prevents its depolymerization. Microfilaments are actin molecules helically polymerized into filaments. Thus, phalloidin can eventually disrupt the dynamic balance of polymerization-depolymerization of microfilaments in cells, resulting in cytotoxity. As phalloidin can keep microfilaments stable, fluorescence-conjugated phalloidin can be conveniently used to examine the morphology and distribution of intracellular microfilaments and is widely used in biological and medical studies.
This microfilaments fluorescent probe has the following characteristics. F-actin can be stained by this probe at nanomolar level. The binding capacity between phalloidin and F-actin in different species is similar, with no or low non-specificity. The stained and unstained areas are significantly different. This probe is very small, with a diameter of about 1.2~1.5nm and the molecular weight less than 2 kD, and does not affect the binding of F-actin to many actin-binding proteins including tropomyosin, pro-tropomyosin and post-tropomyosin. The labeled actin filaments with this probe remain functional (e.g., the labeled muscle fibers can contract and the labeled tropomyosin can continue to move). In plants and animals, the probe has similar affinity for large and small microfilaments. Each phalloidin can bind one actin and can be used for quantitative studies of F-actin in cells.
This product can be used to label microfilaments in cells or tissues. Please refer to Figure 1 for the staining effect of this product.

Figure 1. NRK-52E cells (rat renal tubular epithelial cells) stained with Actin-Tracker Red-555. NRK-52E cells were stained in 12-well plates with the Actin-Tracker Red-555 at a dilution ratio of 1:100. As shown in the figure, the red filamentous microfilaments is clearly visible. The figure is for reference only, which may vary depending on the assay conditions.
The recommended dilution ratio for this product is 1:40-200, allowing the preparation of 8-40ml of staining working solution. When using 200μl of staining working solution per samples, this product is sufficient for staining 40-200 samples.
Packing List:
| Item | Component | Quantity |
| C2203S | Actin-Tracker Red-555 (Microfilaments Red Fluorescent Probe) | 0.2ml |
| Manual | — | 1 copy |
Storage Conditions:
Store at -20℃ in the dark for up to 1 year.
Precautions:
This product should be aliquoted properly to avoid repeated freeze-thaws.
For trace amounts of liquid, centrifuge briefly before each use to collect the liquid at the bottom of the tube.
Fluorescence intensity decays. Avoid light to minimize the quenching of fluorescence.
Coverslips and slides are required but not supplied.
Phalloidin is toxic (LD50: 2mg/kg body weight). Less than 0.2mg of phalloidin is contained in 1ml of Actin-Tracker Red. Please take effective protections when using it.
This product is for R&D only. Not for drug, household, or other uses.
For your safety and health, please wear a lab coat and disposable gloves during the operation.






