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. A number of isoforms are produced. According to EST sequences. The conserved PP2C phosphatase domain (240-639) is interrupted by an insertion of approximately 100 amino acids. No visible phenotype. Belongs to the PP2C family.