Pulling together: an integrated model of Toxoplasma cell invasion.

The protozoan Toxoplasma gondii invades a wide array of animal cells using an actin/myosin-based motor complex to drive active penetration. This broad specificity implies that the parasite has developed a means of using a widely expressed receptor, many different receptors, or perhaps a receptor produced by T. gondii itself. Recently, there has been an explosion in identification of the molecules involved, including those that comprise the 'moving junction' that slides over the parasite as it invades. The emerging model is that invasion comprises at least seven steps that progressively increase the parasite's grip on the host surface, form the moving junction and enlist the motor complex to drive entry. These recent findings have led to new hypotheses regarding the parasite's broad host-specificity.