Deltex 3 Like Protein (DTX3L)

DTX3L functions as an E3 ubiquitin ligase. The deduced 740-amino acid protein has 2 possible nuclear localization signals, a possible nuclear export signal, and a C-terminal RING-HC domain. Compared with other human DTX proteins, BBAP is most similar to DTX3. Northern blot analysis detected a 6.5-kb BBAP transcript in a B-cell lymphoma cell line. Western blot analysis detected BBAP protein at an apparent molecular mass of 89 kD. Mutation analysis revealed that the N terminus of BBAP interacted with the C terminus of BAL. Transfection of BBAP into 293 cells increased global polyubiquitination of proteins. In an in vitro ubiquitination assay, recombinant BBAP became heavily ubiquitinated in a self-ubiquitinated reaction. Deletion analysis showed that the RING finger domain of BBAP was required for its E3 ligase activity.