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. 2016 Apr 11;7:11191. doi: 10.1038/ncomms11191

Figure 10. Model of retromer-mediated recycling of diverse sorting cargoes in T. gondii versus mammalian cells.

Figure 10

No recognizable sorting nexins, Bin/Amphyphysin/Rvs (BAR)-containing domain proteins or lysosomal-like protein degradation have been identified in T. gondii (a), in contrast to the situation in mammalian cells (b). Instead, the retromer-dependent recycling is essential for secretory organelle formation and parasite shape. We propose a model suggesting that Rab7 is the key small GTPase, which is involved in the endocytic recycling of TgSORTLR from endosomes to TGN for another round of ROP and MIC transport and secretory organelle biogenesis. We further raised the possibility that in contrast to mammalian cells, T. gondii lysosomal-like organelles only promote proteolytic maturation of proteins destined to secretion and that the endosomal system is adapted for organellar discharge of virulence-like factors required for the intracellular lifestyle of the parasite. Moreover, we provide the first evidence that a multiple ligand transmembrane transporter TgHP03 is maintained at the surface of T. gondii through endocytic recycling from endosomes to the plasma membrane. BAR, Bin/Amphyphysin/Rvs; MIC, microneme; ROP, rhoptry; TgHP03, T. gondii hypothetical protein 03.