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Expression of a glycosylphosphatidylinositol-anchored Trypanosoma brucei transferrin-binding protein complex in insect cells
- Chaudhri, M., Steverding, D., Kittelberger, D., Tjia, S., Overath, P.
- Proceedings of the National Academy of Sciences of the United States of America 1994 v.91 no.14 pp. 6443-6447
- Trypanosoma brucei, binding proteins, transferrin, structural genes, gene transfer, gene expression, cell lines, Spodoptera frugiperda, phosphatidylinositols, chemical reactions
- The expression site-associated gene ESAG 6 was previously implicated in transferrin binding in the protozoan parasite Trypanosoma brucei. ESAG 6 and the closely related ESAG 7 of T. brucei strain AnTat1.3 have now been expressed in insect cells using the baculovirus expression system. Expression of ESAG 6 alone in insect cells gives rise to a glycosylated protein of approximately 52 kDa, which is cell surface-associated through a glycosylphosphatidylinositol anchor at its C terminus. The ESAG 7 product of about 42 kDa is also glycosylated, but lacks the glycosylphosphatidylinositol modification, and is located intracellularly. No transferrin-binding activity is observed when either ESAG is expressed independently. However, their coexpression results in a cell surface complex of ESAG 6 and 7 products that specifically binds transferrin. This shows that both ESAG 6 and 7 products are necessary and sufficient for binding to transferrin.