We will use high-resolution cryoEM to define the protein components of the apical complex (i.e. conoid) in Toxoplasma and test the importance of key proteins using genetic approaches. This multi-PI project takes advantage of expertise in cryoEM, structural biology of microtubules and associated proteins, to explore the unique architecture of a microtubule organizing center called the conoid in Toxoplasma. Although the importance of the conoid is well recognized, few components have been studied functionally. In new cryoEM studies we have mapped the position and binding partners of the majority of conoid proteins. We will validate these findings, and undertake functional studies, using well-developed tools for reverse genetics and cell biological studies.