| Assay Method Information | |
| | JAK3 Inhibition Assay |
| Description: | Recombinant human JAK3 catalytic domain (amino acids 781-1124; catalog number PV3855) is purchased from Invitrogen. 0.025 mU of JAK3 is incubated with 2.5 μg polyGT substrate (Sigma catalog number P0275) in kinase reaction buffer (25 mM Tris pH 7.5, 0.5 mM EGTA, 0.5 mM Na3VO4, 5 mM b-glycerolphosphate, 0.01% Triton X-100, 1 μM non-radioactive ATP, 0.25 μCi 33P-gamma-ATP (GE Healthcare, catalog number AH9968) final concentrations) with or without 5 μL containing test compound or vehicle (DMSO, 1% final concentration), in a total volume of 25 μL, in a polypropylene 96-well plate (Greiner, V-bottom). After 105 min at 30° C., reactions are stopped by adding of 25 μL/well of 150 mM phosphoric acid. All of the terminated kinase reaction is transferred to prewashed (75 mM phosphoric acid) 96 well filter plates (Perkin Elmer catalog number 6005177) using a cell harvester (Perkin Elmer). Plates are washed 6 times with 300 μL per well of a 75 mM phosphoric acid solution and the bottom of the plates is sealed. 40 μL/well of Microscint-20 is added, the top of the plates is sealed and readout is performed using the Topcount (Perkin Elmer). Kinase activity is calculated by subtracting counts per minute (cpm) obtained in the presence of a positive control inhibitor (10 μM staurosporine) from cpm obtained in the presence of vehicle. The ability of a test compound to inhibit this activity is determined as:Percentage inhibition=((cpm determined for sample with test compound present−cpm determined for sample with positive control inhibitor) divided by (cpm determined in the presence of vehicle−cpm determined for sample with positive control inhibitor))*100.Dose dilution series are prepared for the compounds enabling the testing of dose-response effects in the JAK3 assay and the calculation of the IC50 for each compound. Each compound is routinely tested at concentration of 20 μM followed by a 1/3 serial dilution, 8 points (20 μM-6.67 μM-2.22 μM-740 nM-247 nM-82 nM-27 nM-9 nM) in a final concentration of 1% DMSO. When potency of compound series increased, more dilutions are prepared and/or the top concentration is lowered (e.g. 5 μM, 1 μM). |
| Affinity data for this assay | |
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