(E) FLAG-tagged Taf12 and TAP-tagged Pab1 were affinity purified separately from cells grown in rich conditions (upper panels). TAP-tagged Pab1 was cleaved off from beads using the Tobacco Etch Virus (TEV) protease, releasing a shorter form of Pab1 (CBP-Pab1) in the eluate (E). CBP-Pab1 was then mixed with beads containing FLAG-Taf12 IPs and incubated in a phosphatase buffer, with and without 0.5 µM microcystin. Each reaction was then analyzed by IB and simultaneously probed with anti-FLAG or anti-CBP antibodies (lower panel). 