Trypanosoma brucei: a membrane-associated protein in coated endocytotic vesicles.
Membrane proteins were isolated from purified Trypanosoma brucei coated endocytotic vesicles by phase separation with Triton X-114. The largest abundant membrane protein was a doublet band with a molecular mass of about 77 kDa. A specific antiserum was prepared against this protein by immunization with antigen bands excised from sodium dodecyl sulfate-polyacrylamide gels. Immunoblot analyses with this antiserum showed that the 77-kDa protein was present in other T. brucei, in T. congolense, and in T. vivax bloodstream-stage parasites but absent from procyclic (tsetse fly midgut)-stage trypanosomes. Antigenically related molecules of 58, 300, and 15.5 kDa were also detected. The 300- and 15.5-kDa molecules were not in purified coated vesicles; they were detected in whole bloodstream- and procyclic-form T. brucei organisms. Immunofluorescent studies localized the antigen to the region between the flagellar pocket and the nucleus of bloodstream-form parasites. Ultrastructurally, the antigen was detected on membranes of endosomes and lysosome-like structures that contained endocytosed markers.
International Laboratory for Research on Animal Diseases, Nairobi, Kenya.
P
P
Webster
S Z
SZ
Shapiro
D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis; D005455:Fluorescent Antibody Technique; D007106:Immune Sera / Q000276:immunology; D015151:Immunoblotting; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000032:analysis*; D015800:Protozoan Proteins / Q000032:analysis*; D014346:Trypanosoma brucei brucei / Q000032:analysis* / Q000276:immunology
D000953:Antigens, Protozoan; D007106:Immune Sera; D008565:Membrane Proteins; D015800:Protozoan Proteins