FIGURE 3.

AR interacts with the MED1 N terminus independently of LXXLL motifs. A, schematic representation of MED1 deletion and point mutants. LXXLL motifs are indicated by black bars; LXXLL to LXXAA are indicated by open bars. ERK1/2 phosphorylation sites (threonines 1032 and 1457) are indicated by filled circles; ERK1/2 phosphorylation site mutations (Thr to Ala) are indicated by open circles. B–D, androgen-starved COS cells were transiently transfected with HA-tagged full-length MED1 (FL) or MED1 deletion mutant expression vectors (indicated above the panels) together with a full-length FLAG-AR expression vector and subsequently cultured with or without 10 nm R1881 for another 24 h. Whole cell lysate was then incubated with anti-HA agarose beads, and the precipitated proteins were probed with anti-AR, anti-HA, and anti-MED1 immunoblotting. Arrows indicate specific ectopically expressed MED1 full-length or truncated polypeptides.