Major negative regulator of abscisic acid (ABA) responses during seed germination and cold acclimation. Confers insensitivity to ABA. Modulates negatively the AKT2/3 activity, which mediates K(+) transport and membrane polarization during stress situations, probably by dephosphorylation. Prevents stomata closure by inactivating the S-type anion efflux channel SLAC1 and its activator SRK2E. Represses KIN10 activity by the specific dephosphorylation of its T-loop Thr-198, leading to a poststress inactivation of SnRK1 signaling (PubMed:24179127). 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. Repressed by PYR/PYL/RCAR ABA receptors in an ABA-dependent manner. Interacts with AKT2/AKT3. Interacts with ABA-bounded PYR1, PYL1, PYL2, PYL3, PYL4, PYL9 and PYL12, and with free PYL2, PYL3, PYL4 and PYL13. Binds to and inactivates SLAC1 and SRK2E. The inactivation of SRK2E does not require phosphatase activity. Interacts with CBL1, CBL2, CBL3, CBL5, and CBL7, but not CBL4, CBL6, and CBL9 (PubMed:11181729, PubMed:12034902, PubMed:19407142, PubMed:19955427, PubMed:21596690, PubMed:24165892). Interacts with RGLG1 and RGLG5 (PubMed:27577789). Interacts with KIN10 (PubMed:24179127). Mostly expressed in seeds and leaves, and, to a lower extent, in roots, stems, and flowers, particularly in siliques. Essentially found in the phloem. Repressed by MYB44. Induced by cold stress, drought, high salt, 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. Ubiquitinated by RGLG1 and RGLG5 in response to abscisic acid (ABA). Ubiquitination of PP2CA leads to its degradation by the proteasome. Belongs to the PP2C family.