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

version 3 (curated until May 28, 2011)

Toxoplasma gondii transmembrane microneme proteins and their modular design.

Sheiner, L., Santos, J. M., Klages, N., Parussini, F., Jemmely, N., Friedrich, N., Ward, G. E., Soldati-Favre, D. (2010 Jun 9, Mol Microbiol)

Summary Host cell invasion by the Apicomplexa critically relies on regulated secretion of transmembrane micronemal proteins (TM-MICs). Toxoplasma gondii possesses functionally non-redundant MIC complexes that participate in gliding motility, host cell attachment, moving junction formation, rhoptry secretion and invasion. The TM-MICs are released onto the parasite's surface as complexes capable of interacting with host cell receptors. Additionally, TgMIC2 simultaneously connects to the actomyosin system via binding to aldolase. During invasion these adhesive complexes are shed from the surface notably via intramembrane cleavage of the TM-MICs by a rhomboid protease. Some TM-MICs act as escorters and assure trafficking of the complexes to the micronemes. We have investigated the properties of TgMIC6, TgMIC8, TgMIC8.2, TgAMA1 and the new micronemal protein TgMIC16 with respect to interaction with aldolase, susceptibility to rhomboid cleavage and presence of trafficking signals. We conclude that several TM-MICs lack targeting information within their C-terminal domains, indicating that trafficking depends on yet unidentified proteins interacting with their ectodomains. Most TM-MICs serve as substrates for a rhomboid protease and some of them are able to bind to aldolase. We also show that the residues responsible for binding to aldolase are essential for TgAMA1 but dispensable for TgMIC6 function during invasion.

PubMed: 20545864, full text

Localisation information

TGME49_089630 (MIC16) hypothetical protein

Experimental localisation: microneme during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Transient expression of this new protein carrying a Ty epitope at the C-terminus revealed a micronemal localization in T. gondii tachyzoites (Fig. 2B)."
  • Microscopy type: fixed light
  • Microscopy method: antibody to Ty tag
  • Strain: RH hxgprt-
  • Gene model mapping comments: taken directly from 20545864
  • Localisation record: microneme during intracellular tachyzoite

TGME49_008030 (MIC4, MIC 4) microneme protein MIC4

Experimental localisation: microneme during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Double immunofluorescence analysis by confocal microscopy of intracellular parasites transiently expressing MIC16-Ty carried out with anti-Ty-1 (green) and anti-MIC4 (red), a micronemal marker."
  • Microscopy type: fixed light
  • Microscopy method: antibody directly to protein
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: microneme during intracellular tachyzoite

TGME49_027280 (GRA3) dense granule protein 3

Experimental localisation: dense granule during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Anti-GRA3 or GRASP-YFP were used as dense granules and Golgi markers respectively. "
  • Microscopy type: fixed light
  • Microscopy method: antibody directly to protein
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: dense granule during intracellular tachyzoite

TGME49_061980 (GRASP, GRASP55) gorasp2-prov protein

Experimental localisation: golgi apparatus during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Anti-GRA3 or GRASP-YFP were used as dense granules and Golgi markers respectively. "
  • Microscopy type: fixed light
  • Microscopy method: YFP tag
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: Golgi during intracellular tachyzoite