CHEMBL5738208

ADP-Glo Kinase Activity Assay: Kinase activity of recombinant active full-length human MEK4 (Carna Biosciences) was measured using the ADP-Glo assay (Promega) with 3 μM recombinant full-length human p38α (MAPK14). The concentration of ATP used for high throughput screening was 3 μM (equal to the ATP KM value for MEK4). For ATP competition studies, the ATP concentration was varied (1, 4, 12, or 45 μM). Standard ADP-Glo assay buffer contained 25 mM Tris-HCl, 5 mM beta-glycerophosphate, 2 mM dithiothreitol (DTT), 0.1 mM Na3VO4, and 10 mM MgCl2 at pH 7.5. Triton X-100 was added at a final concentration of 0.01% (w/v) for the aggregation studies. For MEK family profiling, recombinant active full-length human MEK1, 2, 3, 4, 5, 6, and 7 (Carna Biosciences) were used together with 3 μM recombinant full-length substrates. p38α was used for MEK3, 4, and 6. Jnk1B (MAPK8) was used for MEK4 and 7. Erk2 (MAPK1) was used for MEK1 and 2. Erk5 (MAPK7) was used for MEK5. All reactions included 0.6 μM ATP, a concentration that was at least 2-fold below the empirically determined ATP KM values for all MEKs.