Toxoplasma gondii is one of the most common parasitic infections of humans worldwide. Once exposed, humans remain infected with T. gondii for life, and there are no therapeutics capable of eliminating a chronic infection. In the search for novel drug targets, T. gondii is known to contain several unique secretory organelles, one of which is called the rhoptries. Rhoptry organelles contain and s...

The rhoptry is an organelle of the malarial merozoite which has been suggested to play a role in parasite invasion of its host cell, the erythrocyte. A monoclonal antibody selected for reactivity with this organelle identifies a parasite synthesized protein of 110 kD. From biosynthetic labeling experiments it was demonstrated that the protein is synthesized midway through the erythrocytic cycle...

The intracellular parasite Toxoplasma gondii has multiple strategies to alter host cell function, including the injection of rhoptry proteins into the cytosol of host cells as well as bystander populations, but the consequence of these events is unclear. Here, a reporter system using fluorescent parasite strains that inject Cre recombinase with their rhoptry proteins (Toxoplasma-Cre) was combin...

Toxoplasma rhoptry neck protein 4 (TgRON4) is a component of the moving junction macromolecular complex that plays a central role during invasion. TgRON4 is exposed on the cytosolic side of the host cell during invasion, but its molecular interactions remain unclear. Here, we identified host cellular β-tubulin as a binding partner of TgRON4, but not Plasmodium RON4. Coimmunoprecipitation studie...

The rhoptry organelle is critical for the invasion of an erythrocyte by the malaria parasite Plasmodium falciparum. Despite their critical roles, the mechanisms behind their biogenesis are still poorly defined. Our earlier work had suggested that the interaction between the glycosylphosphatidylinositol (GPI)-anchored rhoptry-associated membrane antigen (RAMA) and the soluble rhoptry-associated ...

Rhoptry proteins participate in the invasion of red blood cells by merozoites during the malaria parasite's asexual-stage cycle. Interference with the rhoptry protein function has been shown to prevent invasion, and three rhoptry proteins have been suggested as potential components of a vaccine against malaria. Rhoptry-associated membrane antigen (RAMA) is a 170-kDa protein of Plasmodium falcip...

Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known a...

Host cell invasion by apicomplexan parasites requires formation of the moving junction (MJ), a ring-like apposition between the parasite and host plasma membranes that the parasite migrates through during entry. The Toxoplasma MJ is a secreted complex including TgAMA1, a transmembrane protein on the parasite surface, and a complex of rhoptry neck proteins (TgRON2/4/5/8) described as host cell-a...

A cytosolic pea (Pisum sativum) seed albumin (ALB) and a chimeric protein (PHALB) consisting of the signal peptide and first three amino acids of phytohemagglutinin (PHA) and the amino acid sequence of ALB were expressed in parallel suspension cultures of tobacco (Nicotiana tabacum) cells and their intracellular fates examined. PHALB was efficiently secreted by the cells whereas ALB remained in...