Figure 8. Increase in thermal stability of SnRK2s upon binding of kinase inhibitors.

(A) Incubation with staurosporine, Wee1 inhibitor, and K-252a shifted the Tm of all three ABA-signaling SnRK2s. (B) Chemical structure of the kinase inhibitors that stabilized and increased the Tm of SnRK2.2, 2.3, and 2.6 kinases by at least 3°C. (C) Dose-dependent stabilization of 5 µM SnRK2.3 and SnRK2.6 by staurosporine. (D) Inhibition of SnRK2.6 autophosphorylation by staurosporine and Wee1 inhibitor in a radioactive kinase assay. 100 nM SnRK2.6 were incubated with [³²P]-γ-ATP and increasing concentrations of kinase inhibitors. Reactions were separated by SDS PAGE and dried gels exposed to PhosphorImager screens. A densitometric quantitation of autophosphorylation bands is shown below the autoradiogram.