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The expression level determines the surface distribution of the transferrin receptor in Trypanosoma brucei
Author(s) -
Mußmann Rainer,
Janssen Hans,
Calafat Jero,
Engstler Markus,
Ansorge Iris,
Clayton Christine,
Borst Piet
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03245.x
Subject(s) - biology , trypanosoma brucei , transferrin receptor , transferrin , distribution (mathematics) , expression (computer science) , receptor , microbiology and biotechnology , computational biology , genetics , gene , biochemistry , mathematical analysis , mathematics , computer science , programming language
Summary The transferrin receptor (TfR) of Trypanosoma brucei is a heterodimer attached to the surface membrane by a glycosylphosphatidylinositol (GPI) anchor. The TfR is restricted to the flagellar pocket, a deep invagination of the plasma membrane. The membrane of the flagellar pocket and the rest of the cell surface are continuous, and the mechanism that selectively retains the TfR in the pocket is unknown. Here, we report that the TfR is retained in the flagellar pocket by a specific and saturable mechanism. In bloodstream‐form trypanosomes transfected with the TfR genes, TfR molecules escaped flagellar pocket retention and accumulated on the entire surface, even at modest (threefold) overproduction levels. Similar surface accumulation was observed when the TfR levels were physiologically upregulated threefold when trypanosomes were starved for transferrin. These results suggest that the TfR flagellar pocket retention mechanism is easily saturated and that control of the expression level is critical to maintain the restricted surface distribution of the receptor.