Serine/threonine-protein phosphatase which antagonizes the function of air-2 in the regulation of chromosome cohesion (PubMed:11940606, PubMed:14622138). Dephosphorylates histone H3 at 'Ser-10' (PubMed:10975519). Dephosphorylates translation initiation factor eIF2alpha (PubMed:22719267). Involved in the activation of chloride channel clh-3 during cell swelling and meiotic maturation (PubMed:12163466). 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. Interacts with lab-1; the interaction is direct. Belongs to the PPP phosphatase family. PP-1 subfamily.