AZ191（IC50 of 17 nM） is an effective and specific DYRK1B inhibitor. The specificity of AZ191 for DYRK1B is about 5- and 110-fold greater over DYRK1A and DYRK2, respectively.

DYRK1B:17 nM

AZ191 selectively inhibits DYRK1B serine/threonine kinase activity with no effect on tyrosine kinase autophosphorylation. In HEK-293 cells, AZ191 also displays much greater potency for DYRK1B over DYRK1A, inhibiting CCND1 phosphorylation. In HD1B cells, AZ191 strongly inhibits the levels of the cell-cycle regulators, p21Cip1 and p27Kip1, and increases cell-cycle progression. [1]

Biochemical Binding Affinity – HTRF Assay: The p53-MDM2 HTRF assay is performed in buffer containing 50 mM Tris-HCl, pH 7.4, 100 mM NaCl, 1 mM DTT, 0.02 or 0.2 mg/ml BSA. Small-molecule inhibitors are stored in aliquots as 10 mM stock solutions in DMSO at 4°C in 96-deep-well plates. It is thawed and mixed immediately prior to testing. The compound is incubated with GST-MDM2 and a biotinylated p53 peptide for one hour at 37°C. Phycolink goat anti-GST (Type 1) allophycocyanin and Eu-8044-streptavidin are then added and followed by one hour incubation at room temperature. Plates are read using the Envision fluorescence reader. IC50 values are determined from inter-plate duplicate or triplicate sets of data. Data are analyzed by XLfit4 (Microsoft) using a 4 Parameter Logistic Model (Sigmoidal Dose-Response Model) and the equation Y= (A+ ((B-A)/ (1+ ((C/x)^D)))), where A and B are enzyme activity in the absence or presence of infinite inhibitor compound, respectively, C is the IC50 and D is the Hill coefficient.