ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa
|version 3 (curated until May 28, 2011)|
Identification and characterization of an escorter for two secretory adhesins in Toxoplasma gondii.
Reiss, M., Viebig, N., Brecht, S., Fourmaux, M. N., Soete, M., Di Cristina, M., Dubremetz, J. F., Soldati, D. (2001 Feb 5, J Cell Biol)
The intracellular protozoan parasite Toxoplasma gondii shares with other members of the Apicomplexa a common set of apical structures involved in host cell invasion. Micronemes are apical secretory organelles releasing their contents upon contact with host cells. We have identified a transmembrane micronemal protein MIC6, which functions as an escorter for the accurate targeting of two soluble proteins MIC1 and MIC4 to the micronemes. Disruption of MIC1, MIC4, and MIC6 genes allowed us to precisely dissect their contribution in sorting processes. We have mapped domains on these proteins that determine complex formation and targeting to the organelle. MIC6 carries a sorting signal(s) in its cytoplasmic tail whereas its association with MIC1 involves a lumenal EGF-like domain. MIC4 binds directly to MIC1 and behaves as a passive cargo molecule. In contrast, MIC1 is linked to a quality control system and is absolutely required for the complex to leave the early compartments of the secretory pathway. MIC1 and MIC4 bind to host cells, and the existence of such a complex provides a plausible mechanism explaining how soluble adhesins act. We hypothesize that during invasion, MIC6 along with adhesins establishes a bridge between the host cell and the parasite.
TGME49_091890 (MIC1, Mic 1) microneme protein MIC1Experimental localisation: microneme during tachyzoite
TGME49_008030 (MIC4, MIC 4) microneme protein MIC4Experimental localisation: microneme during tachyzoite
TGME49_018520 (MIC6) microneme protein MIC6Experimental localisation: microneme during tachyzoite
TGME49_033460 (SAG1, SRS29B, P30/SAG1, BSR4, P30) SRS29B (= SAG1, P30)Experimental localisation: parasite plasma membrane during tachyzoite