ECTOPROTEIN TYROSINE PHOSPHATASE-ACTIVITY IN TRYPANOSOMA-CRUZI INFECTIVE STAGES

Live T. cruzi trypomastigotes and amastigotes possess ecto-protein tyr osine phosphatase activity as indicated by the ability of intact cells to catalyze dephosphorylation of tyrosine phosphorylated myelin basic protein, [P-32]TyrRaytide, phosphotyrosine, or the phosphotyrosine an alog p-nitrophenylphosphate (p-NPP). The dephosphorylation of myelin b asic protein (MBP) and p-NPP was inhibited by sodium o-vanadate, zinc chloride and NaF, while dephosphorylation of [P-32]TyrRaytide was inse nsitive to zinc chloride but sensitive to o-vanadate and NaF. In contr ast, live cells were not able to dephosphorylate serine or threonine p hosphorylated peptides ([P-32]Kemptide) or proteins ([P-32]RCM-lysozym e and [P-32]MBP). (C) 1998 Elsevier Science B.V. All rights reserved.