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

version 3 (curated until May 28, 2011)

A malaria parasite formin regulates actin polymerization and localizes to the parasite-erythrocyte moving junction during invasion.

Baum, J., Tonkin, C. J., Paul, A. S., Rug, M., Smith, B. J., Gould, S. B., Richard, D., Pollard, T. D., Cowman, A. F. (2008 Mar 13, Cell Host Microbe)

Malaria parasites invade host cells using actin-based motility, a process requiring parasite actin filament nucleation and polymerization. Malaria and other apicomplexan parasites lack Arp2/3 complex, an actin nucleator widely conserved across eukaryotes, but do express formins, another type of actin nucleator. Here, we demonstrate that one of two malaria parasite formins, Plasmodium falciparum formin 1 (PfFormin 1), and its ortholog in the related parasite Toxoplasma gondii, follows the moving tight junction between the invading parasite and the host cell, which is the predicted site of the actomyosin motor that powers motility. Furthermore, in vitro, the PfFormin1 actin-binding formin homology 2 domain is a potent nucleator, stimulating actin polymerization and, like other formins, localizing to the barbed end during filament elongation. These findings support a conserved molecular mechanism underlying apicomplexan parasite motility and, given the essential role that actin plays in cell invasion, highlight formins as important determinants of malaria parasite pathogenicity.

PubMed: 18329618, full text

Localisation information

PFE1545c (Formin1) formin 1, putative

Experimental localisation: apical during extracellular merozoite
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "Immunofluorescence microscopy of free merozoites demonstrates that PfFormin1 concentrates at the tip of the parasite "
  • Microscopy type: Light
  • Microscopy method: antibody
  • Strain: 3D7
  • Gene model mapping comments: Taken directly from publication
  • Localisation record: apical during free merozoite

PFE1545c (Formin1) formin 1, putative

Experimental localisation: moving junction during merozoite invasion
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "Figure 3. Formin 1 Follows the Moving Tight Junction during Merozoite Invasion of the Erythrocyte "
  • Microscopy type: Light
  • Microscopy method: Polyclonal antibody directly to protein
  • Strain: 3D7
  • Gene model mapping comments: inferred from another publication
  • Localisation record: tight junction during merozoite invasion

PFL0925w (Formin2) formin 2, putative

Experimental localisation: cytoplasm during trophozoite
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "PfFormin2 expression peaks 24 hr postinvasion at the mid trophozoite stage (Figure1B), a time of parasite growth and nuclear division and, by immunofluorescence, localizes diffusely through the trophozoite cell cytoplasm though largely absent from the nucleus (Figure1C) "
  • Microscopy type: Light
  • Microscopy method: antibody
  • Strain: 3D7
  • Gene model mapping comments: Taken directly from publication
  • Localisation record: Cytoplasm during trophozoite

PF11_0168 (RON4, Pf225) rhoptry neck protein 4

Experimental localisation: moving junction during merozoite invasion
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "Prior to invasion, PfFormin1 and PfRON4 colocalize at the apical pole of free merozoites (Figure3A). However, in the rare event of capturing arrested invasion, fluorescence of both PfFormin1 and PfRON4 appear to split to form two distinct foci (a ring in three dimensions) either side of the merozoite at the interface with the erythrocyte (Figure3B). This is consistent with their location at the tight junction during merozoite invasion (Figure3; schematic). "
  • Microscopy type: Light
  • Microscopy method:
  • Strain: 3D7
  • Gene model mapping comments: inferred from another publication
  • Localisation record: tight junction during merozoite invasion

TGME49_006430 (Formin1, FRM1) formin homology 2 domain-containing protein

Experimental localisation: apical conoid during extracellular tachyzoite, inner membrane complex during extracellular tachyzoite, not trophozoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "The Toxoplasma gondii Formin 1 Ortholog Localizes to the Apical Conoid and Pellicle of Free Tachyzoites"
  • Microscopy type: Light, EM
  • Microscopy method: antibody
  • Strain: RH
  • Gene model mapping comments: annotation matches, 18329618 says “It is worth noting that the same study found the formin 1, but not formin 2, ortholog present in conoid-enriched fractions of tachyzoites”
  • Localisation record: apical conoid and pellicle during free tachyzoite, not during trophozoite

TGME49_006430 (Formin1, FRM1) formin homology 2 domain-containing protein

Experimental localisation: moving junction during tachyzoite invasion
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Figure 5. TgFormin1 Localizes to the Moving Junction during Tachyzoite Invasion of Host Cells"
  • Microscopy type: Light
  • Microscopy method: antibody
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: moving junction during tachyzoite invasion