AIP

AIP (ARO-interacting protein) is a component of the ARO-dependent rhoptry biogenesis and positioning pathway in Toxoplasma gondii (PMID:26769898). It localizes to a rhoptry subcompartment, where it binds the armadillo repeats only protein ARO and, together with ARO, associates with adenylate cyclase β (ACβ) (PMID:26769898). Functionally, AIP is required to retain ACβ at the rhoptries: conditional depletion or knockout of AIP causes ACβ to disappear from this compartment (PMID:26769898). Beyond this ACβ-retention role within the ARO pathway, no further mechanistic detail has been characterized in the available corpus.

1. 2016 Medium

   Whether an ARO-associated factor organizes specific rhoptry cargo was unknown; identifying AIP as an ARO binding partner localized to a rhoptry subcompartment placed a new protein within the ARO-dependent rhoptry positioning and biogenesis pathway.

   Evidence Co-immunoprecipitation/pulldown and localization studies identifying ARO partners in T. gondii

   PMID:26769898

   Open questions at the time

   • Reciprocal Co-IP and direct binding interface between AIP and ARO not explicitly demonstrated
   • Whether AIP binds ACβ directly or only via ARO is unresolved
   • The identity of the rhoptry subcompartment and how AIP is targeted there is undefined
2. 2016 Medium

   The functional consequence of AIP was unknown; loss-of-function showed AIP is required to retain adenylate cyclase β at the rhoptries, establishing a specific cargo-retention role downstream of ARO.

   Evidence Conditional depletion/knockout of AIP with assessment of ACβ localization by immunofluorescence in T. gondii

   PMID:26769898

   Open questions at the time

   • Mechanism by which AIP retains ACβ (anchoring vs. stabilization vs. trafficking) is not defined
   • Downstream signaling or invasion consequences of ACβ loss were not established
   • Whether AIP affects other rhoptry cargo beyond ACβ is unknown

• The molecular basis of AIP function — how it is recruited to the rhoptry subcompartment, whether its ACβ interaction is direct, and its role in signaling or invasion — remains open.
• No structural or domain-level characterization of AIP
• No demonstration of direct AIP–ACβ binding
• No phenotypic link to invasion or cAMP signaling