Assay Method Information

Assay Name:  ATR-Complex Inhibition Assay
Description:  Table 7: Compounds were screened for their ability to inhibit ATR kinase, in the presence of partner proteins ATRIP, CLK2 and TopBP1, using a radioactive-phosphate incorporation assay. Assays were carried out in a mixture of 50 mM Tris/HCl (pH 7.5), 10 mM MgCl2 and 1 mM DTT. Final substrate concentrations were 10 μM [g-33P]ATP (3.5 Ci 33P ATP/nmol ATP, Perkin Elmer, Massachusetts, USA) and 800 μM target peptide (ASELPASQPQPFSAKKK) (SEQ ID NO: 1); Isca Biochemicals, Cambridgeshire, UK). Assays were carried out at 25° C. in the presence of 4 nM full-length ATR, 40 nM full-length ATRIP, 40 nM full-length CLK2 and 600 nM TopBP1(A891-S1105). An enzyme stock buffer solution was prepared containing all of the reagents listed above, with the exception of target peptide, ATP and the test compound of interest. This enzyme stock was pre-incubated for 30 minutes at 25° C. 8.5 μL of the enzyme stock solution was placed in a 96-well plate followed by addition of 5 μl of target peptide and 2 μL of DMSO stock containing serial dilutions of the test compound (typically starting from a final concentration of 1.5 μM with 2.5-fold serial dilutions) in duplicate (final DMSO concentration 7%). The plate was pre-incubated for 10 minutes at 25° C. and the reaction initiated by addition of 15 μL [g-33P]ATP (final concentration 10 μM).
Affinity data for this assay
 

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