Identification of Rhoptry Trafficking Determinants and Evidence for a Novel Sorting Mechanism in the Malaria Parasite Plasmodium falciparum
Figure 7
A proposed model for targeting of proteins to the rhoptries.
(A) Proteins destined for the plasma membrane or the apical organelles are co-translationally inserted into the ER and are trafficked to the Golgi. Within the Golgi, proteins destined for the rhoptries (1), the plasma membrane (2), or the micronemes (3) aggregate into distinct sub-domains. Rhoptries and plasma membrane proteins are probably clustered in lipid rafts whereas microneme proteins are excluded from lipid rafts. Specific escorters that are exposed on the cytoplasmic face of the Golgi recruit adaptor and vesicle coat proteins. The sub-domains bud off as individual vesicles and are directed to their respective destinations by specific interactions with the vesicular trafficking machinery. (B) Fusion of the vesicle with the rhoptry delivers the proteins into the rhoptry lumen. Proteolytic processing of RAMA and RAP1 by a rhoptry resident protease releases the proteins from the transient trafficking complex. The LMW complex is retained in the rhoptry bulb via its bulb-retention motif.