Inhibition of Type 2C Protein Phosphatases by ABA Receptors in Abscisic Acid–Mediated Plant Stress Responses

Abscisic acid (ABA) signaling pathway constitutes a key stress response mechanism in plants. Alternate interaction of a type 2C protein phosphatase (PP2C) with either an ABA receptor or a SNF1-related protein kinase 2 (SnRK2) is at the core of regulation of the ABA signaling pathway. Binding of an ABA receptor to a PP2C inhibits the enzymatic activity of the PP2C. Presence of multiple paralogs of ABA receptors and PP2Cs necessitates development of an inhibition assay. Here, we describe how to prepare the recombinant proteins of ABA receptors and PP2Cs for the inhibition assay and how to perform a colorimetry-based inhibition assay.