Functions redundantly with PP2A4, and is involved in establishing auxin gradients, apical-basal axis of polarity and root and shoot apical meristem during embryogenesis. May dephosphorylate PIN1 and regulate its subcellular distribution for polar auxin transport (PubMed:23167545). Involved in the regulation of formative cell division in roots by dephosphorylating ACR4 protein kinase (PubMed:26792519). 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) (By similarity). Interacts with ACR4 (PubMed:26792519). Interacts with TAP46 (PubMed:21216945, PubMed:24357600). Interacts with SIC/RON3 (PubMed:26888284). A number of isoforms are produced. According to EST sequences. Reversibly methyl esterified on Leu-313 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. Belongs to the PPP phosphatase family. PP-2A subfamily.