Atg17Atg29Atg31

Atg17Atg29Atg31 refers to a core protein complex in the Saccharomyces cerevisiae autophagy pathway, formed by the autophagy-related proteins Atg17, Atg29, and Atg31. These components function within the Atg1 kinase complex, which is mobilized under nutrient limitation to initiate autophagosome formation. Atg17 serves as a coiled-coil scaffold that dimerizes to provide a structural platform at the pre-autophagosomal structure (PAS). Atg29 and Atg31 form a heterodimer that associates with Atg17, producing a scaffold essential for organizing the PAS and supporting autophagosome biogenesis.

The complex localizes to the PAS and acts to recruit and stabilize other autophagy factors, including Atg1 kinase and Atg13, thereby coordinating the initiation of phagophore formation. It also contributes to the delivery and tethering of Atg9-containing vesicles, which supply membrane for phagophore expansion. The Atg17-Atg29-Atg31 scaffold operates downstream of nutrient-sensing pathways such as TOR, with the dephosphorylation of Atg13 promoting assembly of the Atg1 complex at the PAS during starvation.

Regulation of the complex involves nutrient status and post-translational modifications that influence protein–protein interactions within the Atg1 pathway. Disruption of any component compromises autophagy efficiency, impairing autophagosome formation and cellular survival under stress conditions. Evolutionarily, the Atg17-Atg29-Atg31 scaffold exemplifies the conserved architectural principle of autophagy initiation machinery, informing how scaffolding complexes organize membranes and factors required for autophagosome biogenesis across eukaryotes.