Autophagic and non-autophagic functions of the Saccharomyces cerevisiae PROPPINs Atg18, Atg21 and Hsv2

Atg18, Atg21 and Hsv2 are homologous beta-propeller proteins binding to PI3P and PI(3,5)P2. Atg18 is thought to organize lipid transferring protein complexes at contact sites of the growing autophagosome (phagophore) with both the ER and the vacuole. Atg21 is restricted to the vacuole phagophore contact, where it organizes part of the Atg8-lipidation machinery. The role of Hsv2 is less understood, it partly affects micronucleophagy. Atg18 is further involved in regulation of PI(3,5)P-2 synthesis. Recently, a novel Atg18-retromer complex and its role in vacuole homeostasis and membrane fission was uncovered.

Automated summary

Atg18, Atg21, and Hsv2 are beta-propeller proteins that bind to PI3P and PI(3,5)P2. Atg18 is involved in organizing lipid transferring protein complexes at contact sites of the growing autophagosome with the ER and the vacuole. Atg21 is restricted to the vacuole-phagophore contact and plays a role in organizing part of the Atg8-lipidation machinery. The function of Hsv2 is not well understood, but it is involved in micronucleophagy to some extent.