Expression of a glycosylphosphatidylinositol-anchored Trypanosoma brucei transferrin-binding protein complex in insect cells.
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 expression 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.
Max-Planck-Institut für Biologie, Abteilung Membranbiochemie, Tübingen, Germany.
M
M
Chaudhri
D
D
Steverding
D
D
Kittelberger
S
S
Tjia
P
P
Overath
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D002417:Cattle; D002460:Cell Line; D015870:Gene Expression; D005822:Genetic Vectors; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D015151:Immunoblotting; D033862:Iron-Binding Proteins; D009036:Moths; D010957:Plasmids; D015800:Protozoan Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D015183:Restriction Mapping; D014162:Transfection; D033863:Transferrin-Binding Proteins; D014346:Trypanosoma brucei brucei / Q000378:metabolism*
D002352:Carrier Proteins; D017261:Glycosylphosphatidylinositols; D033862:Iron-Binding Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D033863:Transferrin-Binding Proteins