ACIDIC PH STRESS INDUCES PROTEIN-TYROSINE PHOSPHORYLATION IN LEISHMANIA-PIFANOI

In order to determine whether in vitro Leishmania exposure to conditio ns comparable to those encountered inside the host cell would induce s pecific signals, we have studied tyrosine phosphorylation patterns in Leishmania pifanoi. Incubation of L. pifanoi at acidic pH resulted in the phosphorylation of several proteins including three of 27, 43 and 51 kDa, as well as the dephosphorylation of a 175 and a 39 kDa protein s in promastigotes recently transformed. In contrast, heat shock at 37 degrees C did not change the tyrosine phosphorylation pattern. Phosph orylation only occurs al pH returned to the initial conditions in 2 h after pH medium 5.0 or lower and reached completion after 1 h. Changes neutralization, indicating a reversible mechanism of phosphorylation. Copyright (C) 1997 Elsevier Science B.V.