Labeled Tubulin Protein

Our fluorescent tubulin conjugates span the visible and infrared spectrum.

We functionalize our cryopreserved bovine tubulin with fluorescent dyes and biomolecules for use in various applications ranging from live cell injection to in vitro nanoscale devices.  The process of “labeling” tubulin protein utilizes amine-reactive compounds that conjugate to random surface lysines of the α/β tubulin heterodimer.  The labeling reaction is carried out with pre-polymerized microtubules in order to prevent the reactive compound  from binding to and disrupting the polymerization interface between two tubulin heterodimers.  The labeled microtubules are subsequently depolymerized and the labeled tubulin protein taken through an additional polymerization and depolymerization cycle to select for maximum polymerization competency.

Our labeled tubulin proteins are guaranteed >99% pure and polymerization competent.  We stock a range of fluorescent conjugates spanning the visible and infrared spectrum in order to cater to a variety of microscopy systems and laser lines/filters. Our Alexa-Fluor® conjugates display enhanced brightness while our Cy5 conjugate displays superior photostability.  We also offer bovine tubulin conjugated with Biotin-XX, a long chain biotin derivative, for binding to streptavidin-coated surfaces.  The longer 14 atom spacer designated by ‘XX’ prevents disruption of tubulin polymerization activity.

Our stock labeled tubulin reagents are available for next-day delivery to your benchtop.  We also offer custom labeling services when a particular fluorophore or biomolecule is desired – inquire here.

Fluorescent Tubulin Protein Conjugates

Fluorescent tubulin spanning the visible and infrared spectrum.  Alexa Fluor® dyes offer enhanced brightness.  Cy5 displays superior photostability.


Vemu A, et al. Severing Enzymes Amplify Microtubule Arrays through Lattice GTP-Tubulin Incorporation. Science. 2018. Link


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Biotinylated Tubulin Protein Conjugates

Long-chain biotin derivative for binding to streptavidin-coated surfaces.

Biotin-XX Tubulin streptavidin bead binding
Biotin-XX Streptavidin Bead Binding
Biotin-XX Tubulin Streptavidin Coverslip
Biotin-XX Tubulin Streptavidin Coverslip

Frequently Asked Questions

Our labeled tubulin proteins are stored in K-glutamate + MgCl2 as this is the ideal buffer for live cell microinjection and frog egg extract applications.  This buffer does not interfere with the polymerization of fluorescent microtubules in vitro.  For generating fluorescent microtubules in vitro, we recommend using a mixture of labeled and unlabeled tubulin proteins in Tubulin PEM Buffer (also known as BRB80).  See our protocols library for detailed microtubule polymerization protocols, including the generation of short, rigid microtubules stabilized by GMPCPP and long, flexible microtubules stabilized by taxol.

It is common to use a mixture of labeled and unlabeled tubulin proteins when generating fluorescent microtubules in vitro in order to minimize any undesirable effects of the dye/biomolecule on microtubule dynamics and save on reagent cost.  The ratio of labeled to unlabeled tubulin protein should be adjusted based on the particular application and desired brightness.  We recommend starting with a labeled to unlabeled tubulin ration of 1:5 and adjusting to achieve the lowest ratio that provides adequate signal for a particular experiment.  See our protocols library for detailed microtubule polymerization protocols or contact the Solutions Team for help in troubleshooting.

We strongly advise against diluting prior to refreezing, as tubulin protein does not store well at concentrations below 20 mg/ml.  If larger handling volumes are desired when working with labeled tubulin, consider mixing with unlabeled tubulin (i.e. Cycled Tubulin, Cat. No. 032005) prior to refreezing.

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