FIG 3.

The Zta transactivation domain regulates Zta ubiquitination. EBV-negative AdAH cells were transfected with or without 5 μg of a ubiquitin (His6-Ub) expression vector as well as 5 μg of the indicated Zta, Zta mutant, or control expression plasmids. Cells were lysed under denaturing conditions and extracts were purified over nickel-NTA beads. The purified material was assayed by Western blot analysis employing either an anti-HA antibody (A and B) or an anti-Zta antibody (C). Expression levels of Zta and its mutants were determined by Western blot analysis of whole-cell lysates. Darker exposure corresponds to longer exposure time. Shown is a schematic illustration of functional domains in Zta. Deletion regions are marked for each of the Zta mutants. Abbreviations: TAD, transactivation domain; DBD, DNA-binding domain; DIM, dimerization domain; bZIP, basic leucine zipper-like domain.