USP32 regulates non-proteolytic LAMTOR1 ubiquitination and Ragulator function

Ubiquitination is among the most prevalent post-translational modifications regulating a great number of cellular functions, and defects in such processes contribute to many diseases. Deubiquitinating enzymes (DUBs) are essential to control the precise outcome of ubiquitin signals. The ubiquitin-specific protease 32 (USP32) differs from all other DUBs as it comprises in addition to its catalytic USP domain and the DUSP domain also multiple EF hands and a C-terminal prenylation site. This unique domain architecture offers various features for the regulation of specific signaling processes by USP32. A SILAC-based proteomic analysis of purified lysosomes revealed an increase in lysosomal hydrolases in organelles isolated from USP32 KO cells as compared to WT cells, suggesting that hydrolases are not sorted correctly to their destination in the absence of USP32.