The Prion-like domain in the exomer-dependent cargo Pin2 serves as a trans-Golgi retention motif

Prion and prion-like domains (PLDs) are found in many proteins throughout the animal kingdom. We found that the PLD in the S. cerevisiae exomer-depen- dent cargo protein Pin2 is involved in the regulation of protein transport and localization. The domain serves as a Pin2 retention signal in the trans-Golgi network (TGN). Pin2 is localized in a polarized fashion at the plasma membrane of the bud early in the cell cycle and the bud neck at cytokinesis. This polarized local- ization is dependent on both exo- and endocytosis. Upon environmental stress, Pin2 is rapidly endocy- tosed, and the PLD aggregates and causes seques- tration of Pin2. The aggregation of Pin2 is reversible upon stress removal and Pin2 is rapidly re-exported to the plasma membrane. Altogether, these data un- cover a role for PLDs as protein localization elements.