Figure 10
A hypothetical pathway for protein trafficking via the endomembrane system in T. vaginalis. With evidence presented herein and elsewhere24, a hypothetical pathway for the membrane trafficking of the hydrogenosomal TvCyP1 and Myb3 transcription factor is proposed. In this scheme, TvCyP2, TvCyP1, and Myb3 in the endoplasmic reticulum (ER) along with a TvBip co-chaperone are assembled into distinct protein complexes, where cis-trans conformational switches on individual proteins may occur. According to the eukaryotic paradigm61, these proteins are likely transported to the Golgi to be further modified and sorted into various vesicles for the delivery to defined membrane compartments. Presumably, a particular Arf protein mediates the budding of distinct vesicles from a specific membrane compartment, whereas a specific Rab protein directs the vesicles to a defined destination. In T. vaginalius, an ill-characterized Myb3IPhmw compartment (see Fig. 5A) may serve as an intermediate network to receive the cargos from the Golgi for further processing before they reach the final destinations. In the scheme, the cargos packed with TvCyP1 and TvCyP2 may be delivered to plasma membrane (PM) from the Golgi as indicated by a solid line. An alternative pathway may exist post-Golgi to deliver some of the cargos packed with TvCyP1 and Myb3 to Myb3IPhmw compartment for further processing before transporting to the hydrogenosomes (Hd) as indicated by a dash line.
