Figure 1. Cdc34 is not the general E2 of the yeast NPC. Ni-purified 6His-ubiquitin conjugated forms of genomically HA-tagged Nup60 (left) or Nup159 (right) were extracted from cells transformed (+) or not (–) with a plasmid encoding 6His-ubiquitin under control of the CUP1 promoter. Cell lysates (upper panels) and Ni-purified material (middle panels) were examined by western blotting with an anti-HA antibody. Ubiquitin expression and efficiency of purification were controlled using an anti-6His antibody (lower panels).