(a) Upon starvation, de-ubiquitination by the Ubp3p/Bre5p ubiquitin protease may trigger the engulfment of ribosomal subunits by autophagic membranes, followed by their degradation in the vacuole. (b) Alternatively, ubiquitination of ribosomal subunits or other factors by an unknown E3 ligase may trigger the engulfment of 60S subunits, and a subsequent de-ubiquitination step promoted by Ubp3p/Bre5p may be required for the maturation and/or fusion of the autophagosome with the vacuole. Ub, ubiquitin. 