Essential for tachyzoite invasion of host cells by controlling rhoptry secretion (PubMed:31492901). Binds to phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphosphate (PIP2) lipids and thus, likely contributes to the assembly of the machinery that docks or primes the rhoptry to the parasite cell membrane prior to the fusion with the host cell membrane (PubMed:31492901). Interacts with RASP1 (PubMed:31492901). Interacts with RASP3 (PubMed:31492901). Localizes to the extremity of the neck of the rhoptry (PubMed:31492901). Associates only with mature rhoptries (PubMed:31492901). Expressed in tachyzoites (at protein level). The C2 domain is a non-calcium binding domain (PubMed:31492901). Cooperates with the PH domain in the binding to phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphosphate (PIP2) (PubMed:31492901). The PH domain cooperates with the C2 domain in the binding to phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphosphate (PIP2). Intracellular replication, parasite egress and motility occur normally; however, host cell invasion is severely reduced (PubMed:31492901). Complete inhibition of rhoptry secretion without affecting microneme secretion or rhoptry morphology (PubMed:31492901).