High impact information on ATG9

• We propose that a pool of Atg11 mediates the anterograde transport of Atg9 to the PAS that is dependent on the actin cytoskeleton during yeast vegetative growth [1].
• We show that Atg11 governs Atg9 cycling through the PAS during specific autophagy [1].
• In the yeast Saccharomyces cerevisiae, the integral membrane protein Atg9 (autophagy-related protein 9) cycles between mitochondria and the preautophagosomal structure (PAS), the nucleating site for formation of the sequestering vesicle, suggesting a role in supplying membrane for vesicle formation and/or expansion during autophagy [1].
• The transmembrane protein Atg9 cycles between the mitochondria and the pre-autophagosomal structure, which is the site of autophagosome biogenesis [2].
• Yeast Atg9p is the first integral membrane protein shown to be essential for the cytoplasm to vacuole targeting (Cvt) pathway and autophagy, whereas its mammalian functional orthologue has yet to be identified [3].

Biological context of ATG9

• Daniel Klionsky gave an overview of Atg9 cycling in yeast and Shigekazu Nagata talked about apoptosis and engulfment of dead cells by macrophages [4].

Anatomical context of ATG9

• We postulate that Atg9 employs a recycling system mechanistically similar to that used at yeast early and late endosomes [5].
• Apg9p/Cvt7p is an integral membrane protein required for transport vesicle formation in the Cvt and autophagy pathways [6].
• A biologically active green fluorescent protein-Aut9 fusion protein was visualized at punctate structures in the cytosol of growing cells [7].

Associations of ATG9 with chemical compounds

• These phenomena correlate with a defect in Atg9 trafficking from the mitochondria to the PAS [8].
• We recently reported that five Atg proteins and phosphatidylinositol-3-phosphate regulate Atg9 recycling from the pre-autophagosomal structure [9].

Physical interactions of ATG9

• Atg9 transiently interacts with Atg23 suggesting that it participates in the recruitment of this protein [10].

Other interactions of ATG9

• We analyzed the trafficking of Atg23 and the integral membrane protein Atg9 in the yeast Saccharomyces cerevisiae [5].
• Apg2 localizes to the previously identified perivacuolar compartment that contains Apg9, the only characterized integral membrane protein that is required for autophagosome/Cvt vesicle formation [11].
• Some important hints to these questions come from Atg9, which is the only integral membrane protein required for autophagosome formation and considered a membrane carrier in autophagy-related pathways [12].

References