Rhoptries are regulated secretory organelles forming part of the apical complex that defines the phylum of Apicomplexa. The discharge of their content crucially contributes to invasion and to the establishment of an intracellular lifestyle. The Armadillo Repeats Only (TgARO) protein is an essential, phylum specific protein that localizes to the cytosolic face of the rhoptry membrane and crucially assists Toxoplasma gondii in invasion by mediating the positioning of the rhoptries to the parasite apex via specific interactions with a myosin motor (TgMyoF). Furthermore, TgARO seems to be involved in the bundling of the rhoptry organelles. The two soluble rhoptry neck proteins, namely adenylate cyclase β (TgACβ) and ARO interacting protein (TgAIP) are two other interacting partners of TgARO. Despite their conservation across the phylum, they are dispensable for parasite survival, which suggests a possible functional redundancy between adenylate cyclases.