Formulation Supplied in 50 mM Tris-HCl (pH 7.5), 150 mM NaCl, 0.25 mM DTT, 0.1 mM EGTA, 0.1 mM EDTA, 0.1 mM PMSF, and 25% glycerol.
Shipping The product is shipped with dry ice or equivalent. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: This
product is stable at ≤ ‑70° C for up
to 1 year from the date of receipt. For optimal storage, aliquot into smaller
quantities after centrifugation and store at recommended temperature. Avoid repeated freeze-thaw cycles.
Active Kinase - Active ITK (0.1 μg/μL) diluted with Kinase Dilution Buffer. Note: These are suggested working dilutions. Optimal dilutions should be determined by each laboratory for each application.
Kinase Assay Buffer I, pH 7.2 - 25 mM MOPS, 12.5 mM beta -glycerolphosphate, 25 mM MgCl2, 5 mM EGTA, 2 mM EDTA. Add 0.25 mM DTT to the Kinase Assay Buffer prior to use.
Kinase Dilution Buffer, pH 7.2 - Kinase Assay Buffer I diluted 5-fold with a 50 ng/μL BSA solution.
10 mM ATP Stock Solution - Prepare the ATP Stock Solution by dissolving 55 mg of ATP in 10 mL of Kinase Assay Buffer I. Store 200 μL aliquots at ≤ -20° C.
[33P]-ATP Assay Cocktail - Prepare 250 μM [33P]-ATP Assay Cocktail in a designated radioactive work area by combining 150 μL of 10 mM ATP Stock Solution, 100 μL of [33P]-ATP (1 mCi/100 μL), and 5.75 mL of Kinase Assay Buffer I. Store 1 mL aliquots at ≤ -20° C.
Substrate - Myelin Basic Protein (MBP) substrate diluted in distilled or deionized water to a final concentration of 1 mg/mL.
Thaw the [33P]-ATP Assay Cocktail in a shielded container in a designated radioactive work area.
Thaw the Active ITK, Kinase Assay Buffer I, Substrate, and Kinase Dilution Buffer on ice.
In a pre-cooled microfuge tube, add the following reaction components bringing the initial reaction volume up to 20 μL. a. Diluted Active ITK: 10 μL b. MBP Substrate (1 mg/mL; on ice): 5 μL
Set up the blank control as outlined in step 3, excluding the addition of the substrate. Replace the substrate with an equal volume of distilled or deionized water.
Initiate the reaction with the addition of 5 μL [33P]-ATP Assay Cocktail, bringing the final volume up to 25 μL. Incubate the mixture in a water bath at 30 °C for 15 minutes.
After the 15 minute incubation, terminate the reaction by spotting 20 μL of the reaction mixture onto individual pre-cut strips of phosphocellulose P81 paper.
Air dry the pre-cut P81 strip and sequentially wash in a 1% phosphoric acid solution (add 10 mL of phosphoric acid to 990 mL of distilled or deionized water) with constant gentle stirring. It is recommended that the strips be washed a total of three times for approximately 10 minutes each.
Count the radioactivity on the P81 paper in the presence of scintillation fluid in a scintillation counter
Determine the corrected cpm by subtracting the blank control value (see step 4) for each sample and calculate the kinase specific activity as outlined below:
Calculation of [33P]-ATP Specific Activity (SA) (cpm/pmol) Specific Activity (SA) = cpm for 5 μL [33P]-ATP/pmol of ATP (in 5 μL of a 250 μM ATP stock solution; i.e. 1250 pmol)
Calculation of Kinase Specific Activity (SA) (pmol/minutes/μg or nmol/minutes/mg) Corrected cpm from reaction / [(SA of 33P-ATP in cpm/pmol) x (Reaction time in minutes) x (Enzyme amount in μg or mg)] x [(Reaction volume) / (Spot Volume)]
The approximate molecular weight is 53 kDa and the average purity is 90%.
ITK is a member of the TEC family of non-receptor tyrosine kinases. ITK is expressed in T cells and is important for T cell development and activation through the antigen receptor. ITK requires prior activation of Lck, ZAP70, and PI3-kinase for efficient activation and shares major substrates with both Lck and ZAP70 (1). ITK knockout mice show multiple effects on T cell development, cytokine production, and T-helper cell differentiation. T cells that lack or express mutant versions of ITK show impaired TCR-induced actin polymerization, cell polarization, and regulation of the signaling events involved in cytoskeletal reorganization (2).
August, A. et al. (2002) Int. J. Biochem. Cell Biol. 34:1184.
Finkelstein, L.D. et al. (2004) Trends Cell Biol. 14:443.
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