- Cell Biology
- Product Type
- Research Area
- New Products
- About Tocris
- Contact Us
Microtubule probes are useful for direct imaging of the microtubule cytoskeletons in cells, with high sensitivity and selectivity, in both in vivo and in vitro settings.
|Cat. No.||Product Name / Activity|
|Fluorescent taxol derivative; microtubule stain|
|Green fluorescent taxol derivative; binds microtubules|
|7315||Taxol Janelia Fluor® 526|
|Green fluorescent taxol derivative; probe for microtubule staining|
|6267||Taxol Janelia Fluor ® 549|
|Yellow fluorescent taxol derivative; probe for microtubule staining|
|6266||Taxol Janelia Fluor® 646|
|Red fluorescent taxol derivative; probe for microtubule staining; protocol available|
Microtubules are found in all eukaryotic cells and are major components of their cytoskeleton. They are hollow cylindrical structures of 20-25 nm in diameter and consist of α- and β-tubulin heterodimers organized into linear protofilaments. They are highly dynamic structures that undergo continual assembly and disassembly in a process driven by GTP hydrolysis. They are polar structures with a fast-growing β-subunits (+) end, and a slow-growing α-subunits (-) end.
Microtubules are important in many cellular processes. They participate in vital cell functions such as intracellular transport, signalling, proliferation and maintain the cell structure. They also form the mitotic spindle which pull eukaryotic chromosomes apart during cell division.
Fluorescent probes present opportunities for the selective imaging of microtubules within the cell cytoplasm. Tocris offers two categories of fluorescent microtubule probes: Flutax and Taxol Janelia Fluor®, both Taxol (Cat. No. 1097) based molecules.
Taxol (often referred to as Paclitaxel) is a diterpenoid originally isolated from yew tree bark. Taxol binds to the β-tubulin subunit in the microtubule lumen which promotes and stabilizes its polymerization, blocking the microtubule dynamics necessary for mitotic cellular functions and leading to cell death. Given its antimitotic and cytotoxic action, Taxol has been used for many years as an antitumor drug particularly in breast, prostate, lung, and ovarian cancer treatment.
The conjugation of fluorescent dyes to Taxol offers a convenient way to visualize microtubule formation and study factors that influence microtubule assembly. It is important to be aware when using these probes that the pharmacological action of Taxol itself remains after conjugation to a fluorescent dye. The stabilization of tubulin polymerization causes cell cycle arrest at the G2/M phase and cell death.
Flutax 1 (Cat. No. 2226) and Flutax 2 (Cat. No. 6254) are probes constituting of Taxol conjugated to the fluorescent dyes fluorescein and Oregon Green 488, respectively. The main difference between the two probes is the pH sensitivity of the dye used. In the physiological pH range, fluorescein is considered highly pH sensitive, whereas Oregon Green 488 is essentially pH insensitive. Both Flutax 1 and Flutax 2 are green fluorescent probes, cell permeable, bright, with similar absorption and emission maxima. They bind selectively to microtubules with high affinity (Ka ≈ 107 M-1, at 37ºC). Their use is compatible with confocal microscopy and flow cytometry.
Taxol Janelia Fluor® probes consist of a Janelia Fluor® dye conjugated to Taxol. They offer significant advantages over spectrally similar dyes in terms of their brightness and photostability. Additionally, Janelia Fluor® dyes are especially well suited to super-resolution microscopy (SRM) techniques.
Tocris provides three Taxol Janelia Fluor® probes for microtubule staining. These include Taxol Janelia Fluor® 526 (Cat. No. 7315; green), Taxol Janelia Fluor® 549 (Cat. No. 6267; yellow) and Taxol Janelia Fluor® 646 (Cat. No. 6266; red). Both Taxol Janelia Fluor® 549 and 646 are designed with the same chemical linkage position as the Flutax compounds. In contrast, Taxol Janelia Fluor® 526 is conjugated at the 3' N position which has been shown to reduce toxicity.
Taxol Janelia Fluor® 526 (Cat. No. 7315) is a fluorogenic green-emitting microtubule probe. This fluorogenic probe is non-fluorescent until bound to microtubules, which allows researchers to carry out no-wash experiments, with bright, low noise signals, perfect for sensitive or low expression experiments. It enables easy multicolor, multi-labeling microscopy experiments. Taxol Janelia Fluor® 526 is suitable for live-cell imaging in confocal microscopy and super-resolution microscopy techniques including STED (standard 775 nm laser for depletion).
|Extinction Coefficient (ε)||118,000 M-1cm-1|
|Quantum Yield (φ)||0.87|
|Application||Confocal microscopy, STED, super-resolution microscopy|
Figure 1: Spectral and photophysical data for Taxol Janelia Fluor® 526
Taxol Janelia Fluor® 646 (Cat. No. 6266) has been utilized for microtubule staining in COS7 cells and visualized using confocal microscopy.
Figure 2: Application of Taxol Janelia Fluor® 646, dye on COS7 cells; COS7 cells were labeled with 3 µM Taxol Janelia Fluor® 646 for one hour at 37°C. Images were taken on a Leica TCS SP8 Confocal Laser Scanning Microscope.
All images kindly provided by Prof. Christian Soeller, University of Exeter; acquired by Evelina Lucinskaite, Anna Meletiou and Alexander Clowsley.
|Cat. No.||Product Name / Activity||Emission color||λEX (nM)||λEM (nM)||Application|
|2226||Flutax 1 Fluorescent taxol derivative; microtubule stain||Green||495||520||Flow cytometry, confocal microscopy|
|6254||Flutax 2 Green fluorescent taxol derivative; binds microtubules||Green||496||526||Flow cytometry, confocal microscopy|
|7315||Taxol Janelia Fluor®526 Green fluorescent taxol derivative; for microtubule staining||Green||531||549||Confocal microscopy, SRM, STED|
|6267||Taxol Janelia Fluor® 549 Yellow fluorescent taxol derivative; for microtubule staining||Yellow||556||575||Flow cytometry confocal microscopy, SRM|
|6266||Taxol Janelia Fluor® 646 Red fluorescent taxol derivative; for microtubule staining||Red||655||671||Flow cytometry confocal microscopy, SRM|
Table 1: Summary of spectral data and imaging application for Taxol derivative microtubule probes
Tocris offers the following scientific literature for Microtubule Probes to showcase our products. We invite you to request* your copy today!
*Please note that Tocris will only send literature to established scientific business / institute addresses.
This product guide provides a background to the use of Fluorescent Dyes and Probes, as well as a comprehensive list of our: