COS-7 cells transfected with MiRP3 (a), MiRP3 and Kv4.2 (b), MiRP3 and Kv4.2–1d4 (c), or Kv4.2–1d4 alone (d), were subjected to lysis and immunopurification (IP) with anti-1d4 antibodies. An additional treatment group (e) consisted of lysate from cells expressing MiRP3 mixed with lysate from cells expressing Kv4.2–1d4, at 4°C for 16 h prior to immunopurification. Blots were probed with antibodies to Kv4.2 (70 kDa) and MiRP3 (21–25 kDa).