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

version 3 (curated until May 28, 2011)

Evidence for a role for a Plasmodium falciparum homologue of Sec31p in the export of proteins to the surface of malaria parasite-infected erythrocytes.

Adisa, A., Albano, F. R., Reeder, J., Foley, M., Tilley, L. (2001 Sep, J Cell Sci)

The malaria parasite, Plasmodium falciparum, spends part of its life cycle inside the enucleated erythrocytes of its human host. The parasite modifies the cytoplasm and plasma membrane of its host cell by exporting proteins beyond the confines of its own plasma membrane. We have previously provided evidence that a plasmodial homologue of the COPII protein, Sar1p, is involved in the trafficking of proteins across the erythrocyte cytoplasm. We have now characterised an additional plasmodial COPII protein homologue, namely Sec31p. Recombinant proteins corresponding to the WD-40 and the intervening domains of the PfSec31p sequence were used to raise antibodies. The affinity-purified antisera recognised a protein with an apparent relative molecular mass of 1.6 x 10(5) on western blots of malaria parasite-infected erythrocytes but not on blots of uninfected erythrocytes. PfSec31p was shown to be largely insoluble in nonionic detergent, suggesting cytoskeletal attachment. Confocal immunofluorescence microscopy of malaria parasite-infected erythrocytes was used to show that PfSec31p is partly located within the parasite and partly exported to structures outside the parasite in the erythrocyte cytoplasm. We have also shown that PfSec31p and PfSar1p occupy overlapping locations. Furthermore, the location of PfSec31p overlaps that of the cytoadherence-mediating protein PfEMP1. These data support the suggestion that the malaria parasite establishes a vesicle-mediated trafficking pathway outside the boundaries of its own plasma membrane - a novel paradigm in eukaryotic biology.

PubMed: 11591825, full text

Localisation information

PFB0640c (Sec31, Sec31p) sec31p

Experimental localisation: cytoplasmic vesicle during ring, cytoplasmic vesicle during schizont, erythrocyte cytoplasmic vesicle during ring, erythrocyte cytoplasmic vesicle during schizont
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "In ring-stage parasites, a slice through the centre of a parasitised erythrocyte revealed labelling of a compartment(s) within the parasite cytoplasm. In addition, punctate structures were observed within the erythrocyte cytosol (Fig. 4a). A confocal slice taken near the surface of the infected erythrocyte provided evidence that the punctate structures are often closely connected to the erythrocyte membrane (Fig. 4b). In more mature stage-infected erythrocytes, the localisation of PfSec31p in compartments within the erythrocyte cytosol was more marked. An uneven or polarised labelling pattern was still observed within the parasite cytoplasm, but PfSec31p appeared to be largely associated with structures in the erythrocyte cytosol that appear vesicular in nature (Fig. 4c,d). This labelling pattern suggests that PfSec31p is exported into the host cell cytoplasm."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: K1
  • Gene model mapping comments: Taken directly from publication
  • Localisation record: Cytoplasmic vesicles and RBC cytoplasm vesicles during ring and schizont

PF11_0098 (ERC, ERC1, Pfs40, Pf39) endoplasmic reticulum-resident calcium binding protein

Experimental localisation: endoplasmic reticulum during trophozoite
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "PfSec31p location only partially overlaps that of the ER-located protein PfERC"
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: K1
  • Gene model mapping comments: inferred from another publication
  • Localisation record: ER during trophozoite

PFD0810w (Sar1p, Sar1) small GTP-binding protein sar1

Experimental localisation: cytoplasmic vesicle during ring, cytoplasmic vesicle during schizont, erythrocyte cytoplasmic vesicle during ring, erythrocyte cytoplasmic vesicle during schizont
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "A polyclonal mouse antiserum against PfSec31(WD) gave an equivalent labelling pattern to that observed with the rabbit antiserum (Fig. 6f,j). A rabbit polyclonal antiserum that recognises the COPII protein, PfSar1p, gave a very similar labelling pattern (Fig. 6g,k), as judged by the almost complete overlap of the fluorescence patterns obtained using probes for these two proteins (Fig. 6h,l)."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: K1
  • Gene model mapping comments: inferred from another publication
  • Localisation record: Cytoplasmic vesicles and RBC cytoplasm vesicles during ring and schizont

PFB0095c (EMP3) erythrocyte membrane protein 3

Experimental localisation: erythrocyte plasma membrane
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "We found that there was little overlap of the location of PfEMP3 with that of PfSec31p. Occasional structures were observed that contained both proteins (Fig. 6p), but the proteins largely occupied separate compartment."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: K1
  • Gene model mapping comments: annotation matches
  • Localisation record: RBC membrane

PF11_0224 (exp-1, EXP1, EXP-1) circumsporozoite-related antigen

Experimental localisation: parasitophorous vacuole
  • Species: Plasmodium falciparum
  • Quote inferring localisation: "Asynchronous infected erythrocytes (K1 strain) were probed with affinity-purified rabbit anti-PfSec31(WD) antiserum followed by a fluorescein-conjugated anti-rabbit IgG (b; green fluorescence) and a murine monoclonal antibody recognising the PV-located protein Exp1 followed by rhodamine-conjugated anti-mouse IgG (c; red fluorescence)."
  • Microscopy type: Light
  • Microscopy method: Monoclonal antibody directly to protein
  • Strain: K1
  • Gene model mapping comments: inferred from another publication
  • Localisation record: PV