Purification and characterization of a tartrate-sensitive acid phosphatase of Trypanosoma brucei.

In search for invariant surface proteins in Trypanosoma brucei bloodstream forms, acid phosphatase was investigated. Earlier work had shown that part of the cellular phosphatase activity is associated with the flagellar pocket of the parasite. It is demonstrated that T. brucei contains at least two membrane-bound enzymes, one is sensitive to the inhibitor L-(+)-tartrate while the other is resistant. The tartrate-sensitive phosphatase was purified to homogeneity by monoclonal antibody affinity chromatography and shown to be a glycoprotein of low abundance (13,000 molecules/cell). It has an apparent molecular weight of 70,000 Da. The usefulness of acid phosphatase as a marker for characterizing the membrane lining the flagellar pocket is discussed.