Related Experiment Videos
The transferrin receptor in African trypanosomes: identification, partial characterization and subcellular
D J Grab1, M K Shaw, C W Wells
1International Laboratory for Research on Animal Diseases, Nairobi/Kenya.
European Journal of Cell Biology
|October 1, 1993
Summary
African trypanosomes need iron, acquired via transferrin (Tf) endocytosis. Researchers identified a novel 90 kDa Tf-binding protein in Trypanosoma brucei brucei, likely acting as the parasite's iron receptor.
Area of Science:
- Parasitology
- Molecular Biology
- Cell Biology
Background:
- Eukaryotic cells, including African trypanosomes, require iron for essential functions like growth and division.
- Iron uptake in trypanosomes occurs through receptor-mediated endocytosis of iron-loaded transferrin (diFe(3+)-transferrin).
- Unlike mammalian cells, transferrin (Tf) in trypanosomes is typically delivered to lysosomes and may not recycle to the cell surface.
Purpose of the Study:
- To characterize a transferrin (Tf)-binding protein with receptor-like properties in Trypanosoma brucei brucei.
- To identify the molecular mass and binding characteristics of this Tf-binding protein.
- To determine the localization of the Tf-binding protein within the parasite and its role in iron acquisition.
Main Methods:
- Incubation of bloodstream forms of T. brucei with [35S]methionine.
- Chromatography of detergent lysates on Sephacryl S-300 columns.
- Immunoprecipitation of Tf/Tf-binding protein complexes using anti-Tf serum.
- Isolation of Tf-binding proteins using diferric Tf-Sepharose.
- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for molecular mass determination.
- Raising antisera against T. brucei Tf-binding proteins and Western blot analysis.
- Immunolocalization studies using specific antisera.
Main Results:
- A major Tf-binding protein with a molecular mass of 88-92 kDa was identified.
- Further analysis indicated a molecular mass of approximately 90 kDa for the Tf-binding protein.
- Each 90 kDa Tf-binding protein molecule was found to bind one molecule of diferric Tf.
- Antibodies against the T. brucei Tf-binding protein inhibited parasite growth in vitro.
- Immunolocalization revealed the protein resides in the flagellar pocket and early endosomal compartments, with additional presence in lysosomes under specific conditions.
Conclusions:
- A 90 kDa Tf-binding protein in T. brucei exhibits receptor-like properties.
- This protein is a strong candidate for the physiological receptor mediating transferrin uptake in these parasites.
- The localization suggests a role in the endocytic pathway for iron acquisition.