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. To better understand the cellular function of USP32, we performed SILAC-based quantitative ubiquitinome analyses to determine potential USP32 substrates. We found proteins involved in endosomal trafficking as well as lysosomal proteins with regulated diGly sites in USP32 knockout (KO) cells.