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

version 3 (curated until May 28, 2011)

The toxoplasma micronemal protein MIC4 is an adhesin composed of six conserved apple domains.

Brecht, S., Carruthers, V. B., Ferguson, D. J., Giddings, O. K., Wang, G., Jakle, U., Harper, J. M., Sibley, L. D., Soldati, D. (2001 Feb 9, J Biol Chem)

The initial stage of invasion by apicomplexan parasites involves the exocytosis of the micronemes-containing molecules that contribute to host cell attachment and penetration. MIC4 was previously described as a protein secreted by Toxoplasma gondii tachyzoites upon stimulation of micronemes exocytosis. We have microsequenced the mature protein, purified after discharge from micronemes and cloned the corresponding gene. The deduced amino acid sequence of MIC4 predicts a 61-kDa protein that contains 6 conserved apple domains. Apple domains are composed of six spacely conserved cysteine residues which form disulfide bridges and are also present in micronemal proteins from two closely related apicomplexan parasites, Sarcocystis muris and Eimeria species, and several mammalian serum proteins, including kallikrein. Here we show that MIC4 localizes in the micronemes of all the invasive forms of T. gondii, tachyzoites, bradyzoites, sporozoites, and merozoites. The protein is proteolytically processed both at the N and the C terminus only upon release from the organelle. MIC4 binds efficiently to host cells, and the adhesive motif maps in the most C-terminal apple domain.

PubMed: 11053441, full text

Localisation information

TGME49_008030 (MIC4, MIC 4) microneme protein MIC4

Experimental localisation: microneme during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Here we show that MIC4 localizes in the micronemes of all the invasive forms of T. gondii, tachyzoites, bradyzoites, sporozoites, and merozoites."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: RH
  • Gene model mapping comments: Blast from AF143487, annotation matches
  • Localisation record: microneme during tachyzoite
  • Comment: disruption of TgMIC6 results in mistrafficking of TgMIC4 and TgMIC1 to dense granules, the “default” secretory pathway

TGME49_008030 (MIC4, MIC 4) microneme protein MIC4

Experimental localisation: microneme during bradyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Here we show that MIC4 localizes in the micronemes of all the invasive forms of T. gondii, tachyzoites, bradyzoites, sporozoites, and merozoites."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: ME49
  • Gene model mapping comments: inferred from another publication
  • Localisation record: microneme during bradyzoite

TGME49_008030 (MIC4, MIC 4) microneme protein MIC4

Experimental localisation: microneme during sporozoite, microneme during merozoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Here we show that MIC4 localizes in the micronemes of all the invasive forms of T. gondii, tachyzoites, bradyzoites, sporozoites, and merozoites."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: VEG
  • Gene model mapping comments: inferred from another publication
  • Localisation record: microneme during sporozoite and merozoite