Cy5 Tubulin

>99% pure tubulin protein conjugated with a far red fluorescent dye.

Labeled Tubulin – Cy5

Catalog Number: 065005
Made in the USA

Product Specifications:

Purity: >99%
Source: bovine
Molecular Weight: ~110 kDa
Maximum Excitation/Emission: 649/670 nm
Labeling Stoichiometry: ~1.5 (check product label)
Form: blue aqueous solution
Concentration: 20 mg/ml
Buffer Conditions: 50 mM K-Glutamate and 0.5 mM MgCl2 (pH 7.0)
Shipping: shipped on dry ice
Storage Conditions: store at -80˚C immediately
Shelf Life: check product label for expiration date


Labeled Tubulin-Cy5 is generated by reacting Cy5 mono-reactive NHS ester with >99% pure tubulin protein, thereby covalently linking the dye to random tubulin surface lysines. Polymerization competency is maintained during the labeling process by reacting the dye with polymerized microtubules and subjecting the tubulin protein to a final polymerization/depolymerization cycle. The final labeled tubulin protein displays maximum absorption at 280 nm and 649 nm, and a labeling stoichiometry ([dye]/[tubulin]) of ~1.5 as determined by spectroscopic analysis (Figure 1). Specific labeling stoichiometries are indicated on the product label. Labeled Tubulin-Cy5 is commonly visualized with a Cy5 filter set with maximum excitation/emission wavelengths of 649/670 nm (see images above). The product is cryopreserved at 20 mg/ml in 50 mM K-Glutamate and 0.5 mM MgCl2 (pH=7.0).

Activity and Applications

Labeled Tubulin-Cy5 will polymerize into microtubules when supplemented with guanosine-5′-triphosphate (GTP), warmed to 37˚C, and kept above its critical concentration. Polymerization activity is detectable in a variety of experimental systems including fluorescence microscopy assays, turbidity assays, and GTPase assays. Labeled tubulin protein is suitable for use in a variety of fluorescent experimental applications including live cell injection, and can be combined with unlabeled tubulin protein (Cycled Tubulin™ highly recommended; Cat. No. 032005) in generating fluorescent microtubules in vitro. Visit our protocols page for common microtubule polymerization protocols, including the generation of short, rigid microtubules stabilized by GMPCPP or long, flexible microtubules stabilized by taxol.

  • in vitro microtubule gliding assays
  • single molecule kinesin and dynein motor assays
  • speckle microscopy
  • live cell injection
  • in vitro nanoscale devices
  • TIRF, STORM, SIM, STED, TPE, confocal, and widefield microscopy

The Most Photostable Tubulin Protein On The Market

Figure 1:

Labeled Tubulin-Cy5 displays maximum absorption at 280 nm and 649 nm. Spectroscopic analysis reveals a peak at 280 nm and 649 nm, indicating absorption by the tubulin protein and Cy5 dye, respectively.

Cy5 - Absorbance Graph
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