USP13(Ubiquitin carboxyl-terminal hydrolase 13) is also named as ISOT3 and belongs to the peptidase C19 family. It is involved in ubiquitin-dependent protein catabolism. USP13 is responsible for MITF deubiquitination, utilizing a short hairpin RNA library against known deubiquitinating enzymes. This protein has 2 isoforms produced by alternative splicing. Modification of target proteins by ubiquitin participates in a wide array of biological functions. Proteins destined for degradation or processing via the 26 S proteasome are coupled to multiple copies of ubiquitin.