The PfRON4 and PfRON5 proteins localize to the rhoptry neck. A, Antibodies raised against PfRON4 and PfRON5 recognize specific protein products in schizont parasite extracts. B, IFAs using the anti-PfRON antibodies reveal staining of the apical tip of free merozoite, in close apposition with the rhoptry bulb markers PfRAP1 and PfRAMA, suggesting a rhoptry neck localization. Scale bar: 0.2μm C, Immunoelectron microscopy confirms that PfRON 4 localizes to the rhoptry neck. Scale bar: 0.1μm

Richard D, Macraild CA, Riglar DT, Chan JA, Foley M, Baum J, Ralph SA, Norton RS, Cowman AF. Interaction between Plasmodium falciparum apical membrane antigen 1 and the Rhoptry neck protein complex defines a key step in the erythrocyte invasion process of malaria parasites. J Biol Chem. 2010 285:14815-22