ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa
|version 3 (curated until May 28, 2011)|
Apicomplexan rhomboids have a potential role in microneme protein cleavage during host cell invasion.
Dowse, T. J., Pascall, J. C., Brown, K. D., Soldati, D. (2005 Jun, Int J Parasitol)
Apicomplexan parasites secrete transmembrane (TM) adhesive proteins as part of the process leading to host cell attachment and invasion. These microneme proteins are cleaved in their TM domains by an unidentified protease termed microneme protein protease 1 (MPP1). The cleavage site sequence (IA downward arrowGG), mapped in the Toxoplasma gondii microneme proteins TgMIC2 and TgMIC6, is conserved in microneme proteins of other apicomplexans including Plasmodium species. We report here the characterisation of novel T. gondii proteins belonging to the rhomboid family of intramembrane-cleaving serine proteases. T. gondii possesses six genes encoding rhomboid-like proteins. Four are localised along the secretory pathway and therefore constitute possible candidates for MPP1 activity. Toxoplasma rhomboids TgROM1, TgROM2 and TgROM5 cleave the TM domain of Drosophila Spitz, an established substrate for rhomboids from several species, demonstrating that they are active proteases. In addition, TgROM2 cleaves chimeric proteins that contain the TM domains of TgMIC2 and TgMIC12.
TGME49_031640 (IMC1, ALV1, IMC, NET1) membrane skeletal protein IMC1Experimental localisation: inner membrane complex during 20 hours after tachyzoite infection
TGME49_000290 (ROM1) rhomboid family domain-containing proteinExperimental localisation: microneme during tachyzoite
TGME49_008030 (MIC4, MIC 4) microneme protein MIC4Experimental localisation: microneme during tachyzoite
TGME49_063290 (ROM2) rhomboid-like protease TgROM2Experimental localisation: golgi apparatus during tachyzoite, not microneme during tachyzoite
TGME49_068590 (ROM4) rhomboid-like protease 4Experimental localisation: parasite plasma membrane during tachyzoite, cytoplasmic structure during after tachyzoite division, residual body during after tachyzoite division