Purity: > 95% by SDS - PAGE Format: Liquid. In 20 mM Tris buffer (pH 8.0) containing 10% glycerol.. Otubain 1, also known as OTuB1, is a member of the OuT (ovarian tumor) superfamily of predicted cysteine proteases and inhibits cytokine gene transcription in the immune system via its interaction with a ubiquitin protease and E3 ubiquitin ligase. This protein is a highly specific ubiquitin iso-peptidase, and cleaves ubiquitin from branched poly-ubiquitin chains but not from ubiquitinated substrates. It is proposed to function in specific ubiquitin-dependent pathways, possibly by providing an editing function of polyubiquitin chain growth. Recombinant OTuB1 protein was expressed in E.coli and purified by using conventional chromatography techniques.