A conserved GTPase complex gates exocytosis for defence and parasitism across alveolates.

An ancient GTPase complex in alveolates gates exocytosis for defence and parasitism, with 100% conservation across ciliates and apicomplexan parasites.

• Why it matters: Understanding the mechanisms of regulated secretion outside metazoans is limited, yet it is crucial for comprehending how these organisms respond to their environments and invade hosts.
• What they did: The study used functional genetics, cryo-electron tomography, and structural modelling on Tetrahymena thermophila and Toxoplasma gondii to investigate the Nd-GTPase-Nd9-NdP1 complex, revealing its role in maintaining organelle secretion in a pre-activation state and enabling stimulus-induced activation.
• The result: Findings demonstrate a conserved gating mechanism of exocytosis in alveolates, with apicomplexan parasites employing an apical vesicle for tighter secretion control, shedding light on parasite virulence strategies.