Associates with the serine/threonine-protein phosphatase PP2A regulatory subunits A and B' to positively regulates beta-oxidation of fatty acids and protoauxins in peroxisomes by dephosphorylating peroxisomal beta-oxidation-related proteins (PubMed:25489022). Involved in the positive regulation of salt stress responses. May function by increasing chloride channel activities on vacuolar membranes (PubMed:27676158). 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. PP2A consists of a common heterodimeric core enzyme, composed of a 36 kDa catalytic subunit (subunit C) and a 65 kDa constant regulatory subunit (subunit A), that associates with a variety of regulatory subunits such as subunits B (the R2/B/PR55/B55, R3/B''/PR72/PR130/PR59 and R5/B'/B56 families). Also interacts with CHIP and TAF12B. Interacts with B'THETA (PubMed:25489022). Interacts with CLC-A, CLC-B, CLC-C and CLC-G (PubMed:27676158). Interacts with B'THETA in the cytosol and peroxisomal import occurs by a piggybacking transport. Induced by salt stress. Reversibly methyl esterified on Leu-307 by leucine carboxyl methyltransferase 1 (LCMT1) and pectin methylesterase 1 (PME1). Carboxyl methylation influences the affinity of the catalytic subunit for the different regulatory subunits, thereby modulating the PP2A holoenzyme's substrate specificity, enzyme activity and cellular localization. Phosphorylation of either threonine (by autophosphorylation-activated protein kinase) or tyrosine results in inactivation of the phosphatase. Auto-dephosphorylation has been suggested as a mechanism for reactivation. Ubiquitinated. CHIP-mediated ubiquitination enhances phosphatase activity after an abiotic stress such as low temperature or darkness (By similarity). No visible phenotype under normal growth conditions, but mutant plants are hypersensitive to salt stress. Belongs to the PPP phosphatase family. PP-2A subfamily.