title: Rab28 function in trypanosomes: interactions with retromer and ESCRT pathways.
abstract: Early endosomal cargo is typically targeted to either a degradative or recycling pathway. Despite established functions for the retromer and ESCRT complexes at late endosomes/multivesicular bodies, the mechanisms integrating and coordinating these functions remain largely unknown. Rab family GTPases are key membrane trafficking organizers and could contribute. Here, in the unicellular organism Trypanosoma brucei, we demonstrate that Rab28 locates to the endosomal pathway and partially colocalizes with Vps23, an ESCRT I component. Rab28 is required for turnover of endocytosed proteins and for lysosomal delivery of protein cargo. Using RNA interference we find that in Rab28-depleted cells, protein levels of ESCRT I (Vps23/28) and retromer (Vps26) are also decreased, suggesting that Rab28 is an important regulator of these factors. We suggest that Rab28 coordinates the activity of retromer-dependent trafficking and ESCRT-mediated degradative pathways.
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP,  UK.
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Lumb
authors.forename: Ka Fai
authors.initials: KF
authors.lastname: Leung
authors.forename: Kelly N
authors.initials: KN
authors.lastname: Dubois
authors.forename: Mark C
authors.initials: MC
authors.lastname: Field
mesh_terms: D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D011992:Endosomes / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D015800:Protozoan Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins
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