Trypanosoma brucei transferrin receptor: Functional replacement of the GPI anchor with a transmembrane domain

The transferrin receptor of Trypanosoma brucei (TbTfR) is a heterodimer glycosylphosphatidylinositol (GPI)-anchored ESAG6 subunit and an ESAG7 subunit. To investigate whether the GPI-anchor essential for function TbTfR, with transmembrane domain instead (ESAG6tmd) was inducibly expressed in bloodstream form trypanosomes. It shown that ESAG6tmd able to dimerise TbTfR can bind transferrin. Fractionation experiments clearly demonstrated transmembrane-anchored exclusively associated membrane fraction. No difference uptake observed between trypanosomes expressing GPI-anchored TbTfR. Differences glycosylation pattern native may indicate different intracellular trafficking transmembrane- TbTfRs. findings suggest not forms T. brucei.