As an obligate intracellular parasite, T. gondii actively invades host cells by an actin-myosindependent mechanism that also requires the coordinated exocytosis of proteins located in apical secretory organelles, namely the micronemes and rhoptries which are characteristic of the Apicomplexa phylum. Successful invasion proceeds through several distinct steps including apical attachment, formation of a moving junction, progression of the parasite through the junction and concomitant establishment of the parasitophorous vacuole within which the parasite will further reside and replicate. Micronemal proteins are mostly adhesins secreted during invasion and then expressed onto the parasite surface and allow motility, recognition and attachment to the host cell through interactions with receptors expressed onto the host cell surface. Rhoptries are club-shaped elongated organelles divided into two distinct suborganellar compartments, the bulbous part and the more anterior thin duct through which rhoptry proteins are secreted but nothing is known about the determinants responsible for maintaining this shape. A proteomic study of the T. gondii rhoptry content led to the identification of about 40 rhoptry proteins, some of which restricted to the bulb and others to the neck. Concomitant to the first molecular characterization of RON proteins came the demonstration that RON4 was secreted and localized to the MJ during invasion. The MJ is a tight connection between the parasite and host cell GDC-0941 plasma membranes that forms at the apical pole and moves progressively to the posterior end of the parasite as it enters. As it serves as an anchor to propel the parasite into the PV, MJ formation is necessary for successful invasion. Although known at the structural level for three decades, the MJ molecular composition and organization has been unraveled only recently. It is now well established that its formation relies on the coordinated secretion of both micronemes and rhoptries. Indeed, the micronemal protein AMA1 is secreted and expressed onto the parasite surface, while the rhoptry neck proteins RON2/4/5/8 are secreted into the host cell, with RON2 being inserted as an integral transmembrane protein into the host plasma membrane allowing a direct interaction with AMA1, while RON4, RON5 and RON8 are translocated beneath the host cell plasma membrane. The secretion of ROP proteins follows RONs discharge but unlike RONs, ROPs are targeted to the PV membrane, to the PV lumen or to the host cell nucleus or cytosol where they hijack the host machinery to MK-1775 modulate the immune response and hence, participate in host cell survival and virulence. ROPs belonging to the ROP2 family have been extensively studied and shown to harbor structural conservation of a protein kinase fold. So far, ROP16 and ROP18 solely have been shown to be active secreted kinases that represent key virulence factors.