:Protein phosphatase methylesterase-1

{{Infobox enzyme

| Name = Protein phosphatase methylesterase-1

| EC_number = 3.1.1.89

| CAS_number =

| GO_code =

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The enzyme protein phosphatase methylesterase-1 (EC 3.1.1.89, PME-1, PPME1; systematic name (phosphatase 2A protein)-leucine ester acylhydrolase{{cite journal | vauthors = Ogris E, Du X, Nelson KC, Mak EK, Yu XX, Lane WS, Pallas DC | title = A protein phosphatase methylesterase (PME-1) is one of several novel proteins stably associating with two inactive mutants of protein phosphatase 2A | journal = The Journal of Biological Chemistry | volume = 274 | issue = 20 | pages = 14382–91 | date = May 1999 | pmid = 10318862 | pmc = 3503312 | doi = 10.1074/jbc.274.20.14382 | doi-access = free }}{{cite journal | vauthors = Xing Y, Li Z, Chen Y, Stock JB, Jeffrey PD, Shi Y | title = Structural mechanism of demethylation and inactivation of protein phosphatase 2A | journal = Cell | volume = 133 | issue = 1 | pages = 154–63 | date = April 2008 | pmid = 18394995 | doi = 10.1016/j.cell.2008.02.041 | doi-access = free }} catalyses the reaction

: [phosphatase 2A protein]-leucine methyl ester + H₂O $\backslash rightleftharpoons$ [phosphatase 2A protein]-leucine + methanol

A key regulator of protein phosphatase 2A.