Together with ABI5, PYL5 and SAPK2, is part of an abscisic acid (ABA) signaling unit that modulates seed germination and early seedling growth. 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. Interacts with PYL5 and SAPK2. Binding to PYL5 is dependent on the presence of abscisic acid (ABA) (PubMed:22071266). Interacts with PYL3, PYL5 and PYL9. Binding to PYL5 and PYL9 is dependent on the presence of ABA (PubMed:26362328). Belongs to the PP2C family.