Golgi membrane proteins YIPF3 and YIPF4 regulate turnover of the Golgi apparatus through autophagy
The degradation of organelles by autophagy is essential for cellular homeostasis. The Golgi apparatus has recently been demonstrated to be degraded by autophagy, but little is known about how the Golgi is recognized by the autophagosome. Using quantitative proteomic analysis and two Golgiphagy-reporter systems that we developed, we found that five-transmembrane Golgi-resident proteins, YIPF3 and YIPF4, constitute a Golgiphagy receptor. The YIPF3-YIPF4 complex interacts with LC3B, GABARAP, and GABARAPL1 via the LIR motif in YIPF3, whose stability is dependent on YIPF4. Phosphorylation of the LIR in YIPF3 seems to be required for YIPF3-ATG8 interaction. Moreover, expression of the YIPF3 LIR mutant caused an elongated Golgi morphology, indicating the importance of Golgi turnover via selective autophagy. The reporter assays that we established will pave the way for future studies to obtain deeper insights into Golgiphagy.