Microtubules polymerized with 1.8 mg/ml Cycled Tubulin (Cat. No. 032005), 0.2 mg/ml Labeled Tubulin-Alexa Fluor® 647 (Cat. No. 064705), and 0.05 mg/ml Labeled Tubulin-Biotin-XX (Cat. No. 033305) bound to the surface of a streptavidin-coated flow cell.


Catalog Number: 033305
Source: Bovine Brain


Labeled Tubulin-Biotin-XX is generated by reacting Biotin-XX succinimidyl ester with Cycled Tubulin (Cat. No. 032005), thereby covalently linking the biomolecule to random tubulin surface lysines. Cycled Tubulin is >99% pure and polymerization competent. These properties are maintained during the labeling process by reacting Cycled Tubulin with the reactive biotin in its polymerized form and subjecting it to a final polymerization/depolymerization cycle. The final product demonstrates an affinity toward streptavidin-coated beads (Figure 1) and streptavidin-coated coverslips (Figure 2). Specific labeling stoichiometries are indicated on the product label. The product is cryopreserved at 20 mg/ml in 50 mM K-Glutamate and 0.5 mM MgCl2 (pH=7.0).


When supplemented with guanosine (GTP or GMPCPP) and warmed to 37°C, Labeled Tubulin-Biotin-XX will polymerize into MTs when above its critical concentration. It is recommended to combine Labeled Tubulin-Biotin-XX with unlabeled tubulin at a ratio of 1:50 to a total tubulin concentration of 2 mg/ml. We highly recommended that Cycled Tubulin (Cat. No. 032005) be used as the unlabeled tubulin source to minimize tubulin heterogeneity, as labeled tubulin products are derived directly from Cycled Tubulin.


Labeled Tubulin-Biotin-XX is supplied for use in a variety of experimental systems including:

  • optical traps and molecular tweezers
  • single molecule kinesin motor assays
  • tubulin affinity columns
  • in vitro nanoscale devices

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Figure 1: Labeled Tubulin-Biotin-XX binds to streptavidin-coated beads. Coomassie G250-stained protein gel of unbound and bound fractions of tubulin samples incubated with Dynabeads® M-280 Streptavidin (Thermo Fisher 11205D). Cycled Tubulin serves as the non-biotinylated negative control. Labeled Tubulin-Biotin-XX fractionates with the streptavidin-coated beads.

Figure 2: Labeled Tubulin-Biotin-XX binds to streptavidin-coated coverslips. Fluorescent images of microtubules incubated in streptavidin-coated flow cells. Microtubules were polymerized with 1.8 mg/ml Cycled Tubulin and 0.2 mg/ml Labeled Tubulin-Alexa Fluor® 647 +/- 0.05 mg/ml Labeled Tubulin-Biotin-XX. Microtubules polymerized with Labeled Tubulin-Biotin-XX are bound to the flow-cell surface.