A reversible protein phosphorylation system is present at the surface of infective larvae of the parasitic nematode Trichinella spiralis

Trichinella spiralis infective Larvae have externally oriented enzymes cata lysing reversible protein phosphorylation on their surface. Incubation of l arvae with exogenous ATP resulted in phosphorylation of surface bound and r eleased proteins. Exposure of the parasites to bile, a treatment which rend ers them infective for intestinal epithelia, resulted in increased release of protein and an altered profile of phosphorylation, Both serine/threonine and tyrosine phosphorylation and dephosphorylation reactions took place at the parasite surface. Examination of the structural characteristics of the larvae following exposure to bile showed that the non-bilayer surface coat was not shed but was structurally reorganised. (C) 2000 Federation of Euro pean Biochemical Societies, Published by Elsevier Science B.V. All rights r eserved.