Immunological characterization of cytoskeletal proteins associated with the basal body, axoneme and flagellum attachment zone of Trypanosoma brucei.

The monoclonal antibody BS7, raised to bovine sperm flagellum cytoskeletal antigens in a previous study, is here reported to detect flagellum-associated structures in Trypanosoma brucei and Crithidia fasciculata. Immunoblotting showed that BS7 cross-reacts with several cytoskeletal T. brucei proteins but phosphatase treatment did not diminish this complex immunoblot reactivity. To characterize further the cross-reactive proteins recognized in T. brucei-cytoskeletons by BS7 each was excised from preparative gels and used as an immunogen for antiserum production. Two proteins, with apparent sizes around 43 and 47 kDa, produced antisera shown to be monospecific by immunoblotting total T. brucei flagellum preparations. Each of these detected the basal body-associated immunofluorescence in T. brucei. Identification of the smaller, 43 kDa, component as a basal body-associated product was supported by the behaviour of a second monoclonal antibody, BBA4, which was also shown to detect the T. brucei basal body complex by immunofluorescence and immunoblots the 43 kDa polypeptide. These observations reveal new components of the trypanosome cytoskeleton. Also, they provide a further example of an immunological approach for identification of interesting, rare components of the T. brucei cytoskeleton starting from a complex mixture of proteins.