STAMBPL1 is a zinc metalloprotease that specifically cleaves 'Lys-63'-linked polyubiquitin chains, but doesn’t cleave 'Lys-48'-linked polyubiquitin chains. The JAMM motif is essential for the protease activity. Recombinant human STAMBPL1 protein, fused to His-tag at N-terminus was expressed in E.coli and purified by using conventional chromatography techniques.