Josephin proteins 1 and 2 are deubiquitinating enzymes (DUBs; peptidase family C86) that contain the Josephin domain, characteristic of the MJD family of DUBs. Josephin-1 (JOSD1) releases 'Lys-63'-linked and 'Lys-48'-linked poly-ubiquitin chains, provided it is monoubiquitinated itself. Josephin-2 (JOSD2) releases 'Lys-63'-linked poly-ubiquitin chains, but does not require ubiquitination to be active. Ubiquitinated JOSD1 is localized to the plasma membrane, whereas JOSD2 is cytoplasmic []. Josephin-like proteins are also found in Arabidopsis thaliana and Drosophila melanogaster.
