FIG 8.

Polyubiquitin binding domain of UFD1L is important for its function in control of postubiquitination of IκBα in HeLa cells upon TNF-α treatment. (A) Sequence alignment between the wild type and the A5 mutant of human UFD1L. (B) The wild type and the A5 mutant of UFD1L were expressed in HeLa cells as Flag tag fusion proteins. A Western blotting approach was employed to show expressed proteins. Their effects in control of postubiquitination of IκBα were evaluated using an RNAi rescue approach. (C) Exogenous Flag-UFD1L was purified using anti-Flag antibody. Its interactions with ubiquitinated IκBα, p97, and NPL4 were shown by Western blotting.