This gene encodes a protein containing zinc finger motifs and a cysteine peptidase domain. The encoded protein functions as a K63-specific de-ubiquitinating enzyme that specifically cleaves long K63-linked polyubiquitin chains in the middle of a chain (i.e. "endo cleavage) rather than by removing the terminal ubiquitin from a chain. This enzyme is thought to be involved in the regulation of DNA repair by cleaving K63-linked ubiquitin chains at repair foci. This protein is related to proteases for the ubiquitin-like modifiers Ufm1 (ubiquitin fold modifier 1) and Atg8/Gabarapl2, but does not have any activity on these modifiers. [provided by RefSeq, Mar 2018]