Pep12 is important for proteasome microautophagy under low glucose conditions.

Autophagic degradation of proteasomes is a highly conserved mechanism for regulating proteasome homeostasis in eukaryotes. Here we show that Pep12, a t-SNARE protein, is important for intralumenal vesicle formation in the vacuole and proteasome microautophagy under low glucose conditions. Deleting in yeast cells, , blocked proteasome fragmentation, by which the ESCRT-dependent microautophagy selectively degrades aberrant proteasomes. Accumulation of aberrant proteasomes interfered with proteasome condensate formation in cells. Autophagic bodies were present, but intralumenal vesicles and proteasome microautophagy were absent in the vacuole of cells. Therefore, Pep12 plays an important role in proteasome microautophagy.