ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa

version 3 (curated until May 28, 2011)

Plasmodium ookinete-secreted proteins secreted through a common micronemal pathway are targets of blocking malaria transmission.

Li, F., Templeton, T. J., Popov, V., Comer, J. E., Tsuboi, T., Torii, M., Vinetz, J. M. (2004 Jun 18, J Biol Chem)

The mosquito midgut ookinete stage of the malaria parasite, Plasmodium, possesses microneme secretory organelles that mediate locomotion and midgut wall egress to establish sporogonic stages and subsequent transmission. The purpose of this study was 2-fold: 1) to determine whether there exists a single micronemal population with respect to soluble and membrane-associated secreted proteins; and 2) to evaluate the ookinete micronemal proteins chitinase (PgCHT1), circumsporozoite and TRAP-related protein (CTRP), and von Willebrand factor A domain-related protein (WARP) as immunological targets eliciting sera-blocking malaria parasite infectivity to mosquitoes. Indirect immunofluorescence localization studies in Plasmodium gallinaceum using specific antisera showed that all three proteins are distributed intracellularly with a similar granular cytoplasmic appearance and with focal concentration of PgCHT1 and PgCTRP, but not PgWARP, at the ookinete apical end. Immunogold double-labeling electron microscopy, using antisera against the membrane-associated protein CTRP and the soluble WARP, showed that these two proteins co-localized to the same micronemal population. Within the microneme CTRP was associated peripherally at the microneme membrane, whereas PgCHT1 and WARP were diffuse within the micronemal lumen. Sera produced against Plasmodium falciparum WARP significantly reduced the infectivity of P. gallinaceum to Aedes aegypti and P. falciparum to Anopheles mosquitoes. Antisera against PgCTRP and PgCHT1 also significantly reduced the infectivity of P. gallinaceum for A. aegypti. These results support the concept that ookinete micronemal proteins may constitute a general class of malaria transmission-blocking vaccine candidates.

PubMed: 15069061, full text

Localisation information

AB247370 (CTRP) gi|110681633|dbj|AB247370.1| Plasmodium gallinaceum pgctrp gene for circumsporozoite protein/thrombospondin-related anonymous protein-related protein, partial cds, strain:7A

Experimental localisation: microneme membrane during ookinete
  • Species: Plasmodium gallinaceum
  • Quote inferring localisation: "Within the microneme CTRP was associated peripherally at the microneme membrane, whereas PgCHT1 and WARP were diffuse within the micronemal lumen."
  • Microscopy type: light, EM
  • Microscopy method: antibody direct to protein
  • Strain: EM
  • Gene model mapping comments: AB247370 taken directly from publication
  • Localisation record: microneme membrane during ookinete

AF064079.1 (CHT1) gi|7530423|gb|AF064079.1| Plasmodium gallinaceum endochitinase precursor, mRNA, complete cds

Experimental localisation: microneme lumen during ookinete, not surface during ookinete
  • Species: Plasmodium gallinaceum
  • Quote inferring localisation: "Within the microneme CTRP was associated peripherally at the microneme membrane, whereas PgCHT1 and WARP were diffuse within the micronemal lumen. … In contrast, PgCHT1, a protein that is not cell surface-associated and lacks predicted transmembrane domains, was found soluble within the central lumen of the same micronemes as those containing CTRP (small (5 nm) gold dots)."
  • Microscopy type: light, EM
  • Microscopy method: antibody direct to protein
  • Strain: EM
  • Gene model mapping comments: AF064079.1 taken directly from publication
  • Localisation record: microneme lumen and not surface during ookinete

No assigned gene identifier (WARP, CHT2) Nothing has been found

Experimental localisation: microneme lumen during ookinete, surface during ookinete
  • Species: Plasmodium gallinaceum
  • Quote inferring localisation: "Within the microneme CTRP was associated peripherally at the microneme membrane, whereas PgCHT1 and WARP were diffuse within the micronemal lumen. … PgWARP, despite the absence of identifiable transmembrane domains or glycosylphosphatidylinositol-anchoring motifs, appears to be present on the ookinete cell surface, including at the posterior end of the parasite."
  • Microscopy type: light, EM
  • Microscopy method: antibody direct to protein
  • Strain: EM
  • Gene model mapping comments: A common gene for all genes not assigned to a gene model taken directly from publication
  • Localisation record: microneme lumen and surface during ookinete
  • Comment: Unable to find GenBank – sequence not submitted?