Recombinant Human Active MAP3K8/Tpl2/COT Protein, CF

• Active Kinase - Active COT (0.1 μg/μL) diluted with Kinase Dilution Buffer III and assayed as outlined in Sample Activity Plot. Note: These are suggested working dilutions and it is recommended that the researcher perform a serial dilution of Active COT for optimal results.
• Kinase Assay Buffer I - 25 mM MOPS, pH 7.2, 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 III - Kinase Assay Buffer I diluted at a 1:4 ratio (5X dilution) with a 50 ng/μL BSA solution.
• 10 mM ATP Stock Solution - Prepare 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 - Inactive MEK1 and ERK1 were activated in a coupled reaction. Myelin Basic Protein (MBP) diluted in distilled or deionized water to a final concentration of 1 mg/mL was subsequently used as a substrate for the activated ERK1.

1. Thaw the Active COT, Kinase Assay Buffer I, and inactive MEK1 and ERK1 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 COT: 10 μL
   b. Inactive MEK1 (0.2 μg/μL): 2 μL
   c. Inactive ERK1 (0.2 μg/μL): 3 μL
   d. Kinase Dilution Buffer: 5 μL
2. Start the reaction with the addition of 5 μL ATP (250 μM) and incubate in a water bath at 30 °C for 25 minutes.
3. After the 25 minute incubation, remove 5 μL and add to the following reaction components bringing the initial reaction volume up to 20 μL:
   a. Reaction Mixture: 5 μL
   b. Distilled water (on ice): 10 μL
   c. MBP Substrate (1 mg/mL; on ice): 5 μL
4. 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 water.
5. Initiate the reaction with the addition of 5 μL [³³P]-ATP Assay Cocktail, bringing the final volume up to 25 μL and incubate the mixture in a water bath at 30 °C for 15 minutes.
6. 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.
7. 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.
8. Count the radioactivity on the P81 paper in the presence of scintillation fluid in a scintillation counter.
9. 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/pmole 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)]

Scientific Data

SDS-PAGE View Larger

The approximate molecular weight is 70 kDa and the purity is > 75%.