Plays an important role in regulating cell division and growth by reversible phosphorylation signaling (PubMed:14575702, PubMed:12950916, PubMed:27758870). May play important roles in regulating cellular metabolism and signaling pathways, which could mediate the growth and development of the cell (PubMed:31958639). Plays a role in establishing and maintaining infection (PubMed:27758870). Dephosphorylates several proteins, including the kinases PknA, PknB, PknD, PknE, PknF, PknH, PknJ and Pyk, the transcriptional regulatory proteins EmbR and EthR, the osmosensory protein OprA and the dimycocerosyl transferase PapA5 (PubMed:14575702, PubMed:12950916, PubMed:15967413, PubMed:16817899, PubMed:17411339, PubMed:19826007, PubMed:20520732, PubMed:21423706, PubMed:31958639). In vitro, dephosphorylates the phosphorylated Ser/Thr residues of myelin basic protein (MBP), histone and casein phosphorylated at Ser/Thr residues, but fails to dephosphorylate phosphotyrosine residue of these substrates (PubMed:14575702, PubMed:12950916). H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 3 Mn(2+) ions per subunit (PubMed:15530359). The third manganese ion is unlikely to be involved in catalysis but contributes instead to stabilize a flap segment, which is partially disordered in the absence of bound metal (PubMed:17961594). Activity is modulated by phosphorylation (PubMed:21423706). Phosphorylated phosphatase is more active than its unphosphorylated equivalent (PubMed:21423706). Inhibited partially by NaF and cyclosporine (PubMed:14575702). Also inhibited by zinc ions and inorganic phosphate (PubMed:21423706). 78 interactors between PstP and Mtb proteins were identified using Mtb proteome microarray, including proteins involved in diverse aspects of cellular pathways and biological processes, which contain cellular metabolic process, biosynthetic process, gene expression and transcription regulation processes (PubMed:31958639). Interacts with EthR and may interfere with its DNA binding activity (PubMed:31958639). Phosphorylated on several threonine residues by PknA and PknB. Depletion of PstP compromises mycobacterial growth and causes marginal elongation of cells. Depletion of PstP in M.tuberculosis negatively impacts its survival in mice and decreases the bacillary load even in an established infection. Overexpression leads to elongated cells and partially compromised survival. Was identified as a high-confidence drug target. It is uncertain whether Met-1 or Val-4 is the initiator. Was reported to dephosphorylate the penicillin-binding protein PBPA. However, this publication has been retracted because the published versions of some figures were modified prior to publication.