title: A MORN Repeat Protein Facilitates Protein Entry into the Flagellar Pocket of Trypanosoma brucei.
abstract: The parasite Trypanosoma brucei lives in the bloodstream of infected mammalian hosts, fully exposed to the adaptive immune system. It relies on a very high rate of endocytosis to clear bound antibodies from its cell surface. All endo- and exocytosis occurs at a single site on its plasma membrane, an intracellular invagination termed the flagellar pocket. Coiled around the neck of the flagellar pocket is a multiprotein complex containing the repeat motif protein T. brucei MORN1 (TbMORN1). In this study, the phenotypic effects of TbMORN1 depletion in the mammalian-infective form of T. brucei were analyzed. Depletion of TbMORN1 resulted in a rapid enlargement of the flagellar pocket. Dextran, a polysaccharide marker for fluid phase endocytosis, accumulated inside the enlarged flagellar pocket. Unexpectedly, however, the proteins concanavalin A and bovine serum albumin did not do so, and concanavalin A was instead found to concentrate outside it. This suggests that TbMORN1 may have a role in facilitating the entry of proteins into the flagellar pocket.
authors: Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, Vienna, Austria brooke.morriswood@uni-wuerzburg.de katy.schmidt@meduniwien.ac.at.
authors: Brooke
authors: B
authors: Morriswood
authors: Department of Cell Biology and Ultrastructure Research, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria brooke.morriswood@uni-wuerzburg.de katy.schmidt@meduniwien.ac.at.
authors: Katy
authors: K
authors: Schmidt
mesh_terms: D004705:Endocytosis; D005407:Flagella / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D015800:Protozoan Proteins