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. Author manuscript; available in PMC: 2022 Aug 1.
Published in final edited form as: Trends Biochem Sci. 2021 Jan 25;46(8):630–639. doi: 10.1016/j.tibs.2020.12.013

Figure 4. Macro-ER-phagy in yeast.

Figure 4.

Yeast Atg40 has a domain structure similar to mammalian FAM134B, yet it localizes to the tubular ER, like RTN3L. In yeast, the sheets and tubules in the cytoplasm, and at the cell cortex, are referred to as the cortical ER. Atg40 is largely present on the cortical ER, while Atg39 is principally localized in the nuclear envelope. Atg40, which contains a reticulon-like domain, recruits Atg8 via a LIR motif to initiate cortical macro-ER-phagy. Autophagosome-driven fragmentation of the cortical ER occurs at ER-phagy sites (ERPHS) with the aid of the Lst1-Sec23 complex. In contrast, transport vesicles bud from the ER at ER exit sites (ERES), where the COPII coat complex is assembled. Soluble secretory cargo proteins are loaded into vesicles via a receptor-mediated process, while transmembrane cargo proteins interact with the COPII coat subunits or specific adaptors.