An evolutionarily conserved coiled-coil protein implicated in polycystic kidney disease is involved in basal body duplication and flagellar biogenesis in Trypanosoma brucei.

Trypanosoma brucei is a flagellated protozoan with a highly polarized cellular structure. TbLRTP is a trypanosomal protein containing multiple SDS22-class leucine-rich repeats and a coiled-coil domain with high similarity to a mammalian testis-specific protein of unknown function. Homologues are present in a wide range of higher eukaryotes including zebra fish, where the gene product has been implicated in polycystic kidney disease.

PtdIns-specific MPR pathway association of a novel WD40 repeat protein, WIPI49.

WIPI49 is a member of a previously undescribed family of WD40-repeat proteins that we demonstrate binds 3-phosphorylated phosphoinositides. Immunofluorescent imaging indicates that WIPI49 is localized to both trans-Golgi and endosomal membranes, organelles between which it traffics in a microtubule-dependent manner. Live cell imaging establishes that WIPI49 traffics through the same set of endosomal membranes as that followed by the mannose-6-phosphate receptor (MPR), and consistent with this, WIPI49 is enriched in clathrin-coated vesicles.

Rab5 and Rab11 mediate transferrin and anti-variant surface glycoprotein antibody recycling in Trypanosoma brucei.

The mammalian-infective bloodstream form of Trypanosoma brucei possesses a highly active endocytotic system. Evasion of the host immune response by T. brucei is dependent on antigenic variation of VSG (variant surface glycoprotein), but additional mechanisms for removal of surface-bound antibody also operate.

TbRAB18, a developmentally regulated Golgi GTPase from Trypanosoma brucei.

The trypanosomal secretory system is broadly similar to that of higher eukaryotes as proteins enter the system via the endoplasmic reticulum and are transported to the Golgi complex for elaboration of glycan chains. Importantly N-glycan processing is stage specific with only the bloodstream form (BSF) processing beyond the oligomannose form. Increased complexity of the BSF Golgi apparatus, as evidenced by morphological studies, may underpin this higher activity, but few trypanosome-specific Golgi proteins have been described that may play a role in this developmental alteration.