Zinc metalloprotease that specifically cleaves 'Lys-63'- linked polyubiquitin chains (PubMed:18758443, PubMed:35114100). Acts as a positive regulator of the TORC1 signaling pathway by mediating 'Lys- 63'-linked deubiquitination of SESN2, thereby inhibiting SESN2- interaction with the GATOR2 complex (PubMed:35114100). Does not cleave 'Lys-48'-linked polyubiquitin chains (PubMed:18758443). . This is the function of STAMBPL1 (STAM binding protein like 1, ENSG00000138134).