The expression and localization of PfRON3 in Plasmodium falciparum merozoites. (B) PfRON3 was primarily expressed during the late trophozoite stage, with a peak in transcription levels at 40 hours post-invasion. The subcellular localization of PfRON3 was confirmed that it is a merozoite rhoptry bulb protein. Additionally, the recombinant form of PfRON3 protein bound to the erythrocyte and was recognized by sera collected from malaria endemic areas in Africa, and anti-PfRON3 antibodies significantly inhibited merozoite invasion into erythrocytes.. PfRON3 is expressed inside Plasmodium merozoites. Schizont stage parasites were dual-labeled with PfRON3-specific antibodies in combination with MSP1-42 antibodies. Nuclei are stained with DAPI. MSP1-42 protein was located at the merozoite membrane (red fluorescence) and RON3 was located inside merozoites (green fluorescence). (C) PfRON3 location shown via immunoelectronic microscopy. The section of merozoite in mature schizonts was labeled with purified rabbit anti-PfRON3 antibodies and subsequently detected with a secondary antibody conjugated with gold particles (arrow-headed). The black dots indicate signals from gold particles localized in the rhoptry body. Bar represents 200 nm. Zhao X, Chang Z, Tu Z, Yu S, Wei X, Zhou J, Lu H, Jiang N, Chen Q. PfRON3 is an erythrocyte-binding protein and a potential blood-stage vaccine candidate antigen. Malar J. 2014. PMID: 25495792