MRAP can interact and co-localize with both MC2 and MC5 receptors. A and B, CHO cells expressing MRAP-V5 together with HA-MC2 or HA-MC5 receptor (A) or HA-β2-adrenergic receptor (B) were lysed, and receptors were immunoprecipitated with anti-HA antibody and MRAP with anti-V5 antibody. Proteins were resolved on SDS-PAGE, and receptors were probed with anti-HA antibody. C, live CHO cells transfected with MC2 receptor-YFP-F1 and MRAP-YFP-F2. D, live CHO cells transfected with MC5 receptor-YFP-F1 and MRAP-YFP-F2. *, IgG heavy chain.