Repressor of the abscisic acid (ABA) signaling pathway that regulates numerous ABA responses, such as stomatal closure, osmotic water permeability of the plasma membrane (Pos), high light stress, response to glucose, seed germination and inhibition of vegetative growth. During the stomatal closure regulation, modulates the inward calcium-channel permeability as well as H(2)O(2) and oxidative burst in response to ABA and dehydration. Represses GHR1 and, to some extent, SRK2E/OST1, kinases involved in the regulation of SLAC1-dependent stomatal closure (PubMed:22730405). Controls negatively fibrillin that is involved in mediating ABA-induced photoprotection. May be implicated in ABA content regulation. Involved in acquired thermotolerance of root growth and seedling survival. Required for the Erwinia amylovora harpin-induced (HrpN) drought tolerance. Involved in the hydrotropic response. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 magnesium or manganese ions per subunit. Phosphatase activity repressed by oxidized ATGPX3, free fatty acids (e.g. arachidonic acid (20:4) and Linolenic acid (18:3)) and by H(2)O(2). Repressed by PYR/PYL/RCAR ABA receptors in an ABA-dependent manner. Optimum pH is 8. Interacts with SPK1, CIPK15/PKS3, GPX3, SCAR1, SCAR2, SCAR3 and SCARL. Interacts also with CIPK24/SOS2. Binds to the fibrillin precursor protein. Interacts with ABA-bounded PYR1, PYL1, PYL2, PYL3, PYL4, PYL5, PYL6, PYL8 and PYL9, and with free PYL2, PYL3 and PYL4. Interacts with and represses GHR1, and, to a lesser extent, SRK2E/OST1 (PubMed:22730405). Repressed by MYB44 and ERF4. Induced by salt stress and ABA. The 'lock' site stabilizes the complex made of PP2C, ABA and PYR/PYL/RCAR receptor by keeping receptor 'gate' and 'latch' loops in closed positions. The reduced form of ABI2 is converted to the oxidized form by the addition of oxidized GPX3 or H(2)O(2). Belongs to the PP2C family.