Serine/threonine-protein phosphatase that possesses phosphatase activity toward para-nitrophenyl phosphate (pNPP) in vitro (PubMed:21222654, PubMed:26943172). Acts as negative regulator of abscisic acid (ABA) signaling. In vitro, can dephosphorylate and inhibit the kinase activity of SRK2E/SNRK2.6, an activator of ABA signaling. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 manganese ions per subunit. Phosphatase activity is strongly reduced by the protein phosphatase inhibitor 2 (I-2) (PubMed:21222654, PubMed:26943172). Phosphatase activity is strongly reduced by PYL11, an abscisic acid (ABA) receptor (PubMed:26943172). Interacts with I-2, SRK2D/SNRK2.2, SRK2I/SNRK2.3, SRK2A/SNRK2.4, SRK2E/SNRK2.6, SRK2C/SNRK2.8, PYL4, PYL9 and PYL11. Expressed in cotyledons, leaves and flowers. No visible phenotype under normal growth conditions, but mutant seedlings exhibit hypersensitivity to abscisic acid (ABA) or salt treatments. Belongs to the PPP phosphatase family. PP-1 subfamily.