HiLyte Fluor™ 488 labeled microtubules formed from HiLyte Fluor™ 488 labeled tubulin.
Product Uses Include
Porcine brain tubulin (>99% pure, see Cat. # T240) has been modified to contain covalently linked HiLyte Fluor™ 488 (HiLyte Fluor is a trademark of Anaspec Inc, CA) at random surface lysines. An activated ester of HiLyte Fluor™ 488 was used to label the protein. Labeling stoichiometry was determined by spectroscopic measurement of protein and dye concentrations (dye extinction coefficient when protein bound is 76,000M-1cm-1). Final labeling stoichiometry is 1-2 dyes per tubulin heterodimer. HiLyte Fluor™ 488 labeled tubulin can be detected using a filter set of 440-460 nm excitation and 500-520 emission. HiLyte Fluor™ 488 tubulin is in a versatile, stable and easily shipped format. It is ready for micro-injection or in vitro polymerization. Cytoskeleton, Inc. also offers AMCA (Cat. # TL440M), rhodamine (Cat. # TL590M), X-rhodamine (Cat. # TL620M) and HiLyte Fluor™ 647 (Cat. # TL670M) labeled tubulins of the same quality.
The protein purity of the tubulin used for labeling is determined by scanning densitometry of Coomassie Blue stained protein on a 4-20% polyacrylamide gel. The protein used for TL488M is >99% pure tubulin (Figure 1 A). Labeled protein is run on an SDS gel and photographed under UV light. Any unincorporated HiLyte Fluor™ 488 dye would be visible in the dye front. No fluorescence is detected in the dye front, indicating that no free dye is present in the final product (Figure 1 B).
Figure 1: HiLyte Fluor™ 488 tubulin protein purity determination. A 50 µg sample of unlabeled tubulin protein was separated by electrophoresis in a 4-20% SDS-PAGE system and stained with Coomassie Blue (A). Protein quantitation was performed using the Precision Red Protein Assay Reagent (Cat. # ADV02). 20 µg of the same protein sample was run in a 4-20% SDS-PAGE system and photographed directly under UV illumination (B).
The biological activity of HiLyte Fluor™ 488 tubulin is assessed by a tubulin polymerization assay. To pass quality control, a 5 mg/ml solution of AMCA labeled tubulin in G-PEM plus 5% glycerol must polymerize to >85%. This is comparable to unlabeled tubulin under identical conditions.
Rostovtseva et al., 2012. Membrane lipid composition regulates tubulin interaction with mitochondrial voltage dependent anion channel. J. Biol. Chem. doi: 10.1074/jbc.M112.378778.
Question 1: Can HiLyte Fluor™ 488-labeled tubulin (Cat. # TL488M) be used to monitor tubulin dynamics in living cells?
Answer 1: Yes, all of Cytoskeleton’s fluorescently-labeled tubulins, including HiLyte Fluor™ 488-tubulin can be micro-injected into cells to study tubulin localization and dynamics in living cells. Please see the brief protocol on the product datasheet (Cat. # TL488M and these papers for guidance on micro-injecting cells with fluorescently-labeled proteins (Smilenov et al., 1999. Focal adhesion motility revealed in stationary fibroblasts. Science. 286, 1172-1174; Lopez-Lluch et al., 2001. Protein kinase C-dC2-like domain is a binding site for actin and enables actin redistribution in neutrophils. Biochem. J.357, 39-47; Lim and Danuser, 2009. Live cell imaging of F-actin dynamics via fluorescent speckle microscopy (FSM). J. Vis. Exp. 30, e1325, DOI: 10.3791/1325;
Question 2: What is the best way to store HiLyte Fluor™ 488-labeled tubulin to maintain high activity?
Answer 2: The recommended storage condition for the lyophilized tubulin product is 4°C in the dark with desiccant to maintain humidity at <10%. Under these conditions the protein is stable for 6 months. Lyophilized protein can also be stored desiccated at -70°C where it will be stable for 6 months. However, at -70°C the rubber seal in the lid of the tube could crack and allow in moisture. Therefore we recommend storing at 4°C. If stored at -70°C, it is imperative to include desiccant with the lyophilized protein if this storage condition is utilized. After reconstituting the protein as directed, the concentrated protein in G-PEM buffer should be aliquoted, snap frozen in liquid nitrogen and stored at -70°C (stable for 6 months). NOTE: It is very important to snap freeze the tubulin in liquid nitrogen as other methods of freezing will result in significantly reduced activity. Defrost rapidly by placing in a room temperature water bath for 1 min. Avoid repeated freeze/thaw cycles.
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