Dissecting the apicomplexan rhoptry neck proteins

Plasmodium rhoptry proteins: why order is important

“…These studies have revealed that RON4 forms an outer ring encircling the protein rings of AMA1 and a hemagglutinin epitope-tagged version of RON2 during merozoite invasion [37,53]. These nested RON4/AMA1 and RON4/RON2-HA rings clearly delineate the invaded, PVM-surrounded anterior of the parasite from its extracellular posterior, consistent with the hypothesis that the TJ is a parasite-derived protein ring that facilitates invasion into host cells (reviewed in [4,46]). Although RON2 and its micronemal partner AMA1 have not yet been imaged together by super-resolution microscopy, their localization within the RON4 ring is in keeping with previous data that indicate a direct interaction with each other.…”

“…origins with other Apicomplexans. There are already some excellent recent reviews on the neck proteins [1,46], and we instead focus in this section on the use of emerging technologies and methodologies that have further increased our understanding of how these proteins function.…”

“…RALP1 colocalizes with RAP1 in merozoites, but because it is not observed in newly invaded cells its function is unknown. Several other proteins that localize to the Plasmodium rhoptry neck remain to be functionally characterized, including Pf34, AARP, and RON6 ( Figure 1, reviewed in [46]). Whether these proteins are involved in adhesion or invasion requires further investigation, but at present leaves open the possibility that rhoptry neck proteins may engage in even more diverse functions.…”

Identification of the Plasmodium falciparum rhoptry neck protein 5 (PfRON5)

“…The presence of orthologous genes which encode for RON proteins in different Apicomplexa members suggests that the TJ complex formation is a conserved mechanism in this phylum (Proellocks et al, 2010). TgRON2 and TgRON4 homologous proteins have been…”

Evidence of Intraflagellar Transport and Apical Complex Formation in a Free-Living Relative of the Apicomplexa

“…The apical complex of all apicomplexans contains an apical polar ring that serves as an organizing center for the subpellicular microtubules. Rhoptries and micronemes-secretory organelles that deliver the enzymes necessary for host cell invasion-extend from the apical polar ring into the cell body (16,17). In some apicomplexans (for example, Toxoplasma), a conoid-a cone-shaped arrangement of tubules made up of unusual polymers of tubulin (18)-extends from the apical polar ring into the extreme anterior (apical) end of the cell.…”