Dimerization of the melanocortin 4 receptor: a study using bioluminescence resonance energy transfer

The melanocortin 4 receptor is important in the regulation of satiety. In this study we have investigated the propensity of the MC4 receptor to homodimerize. MC4 receptors with either a modified green fluorescent protein (GFP(2)) or Renilla luciferase (RLuc) at their C-terminus were constructed. These receptors showed equivalent binding and functional properties to the wild-type MC4 receptor. Bioluminescence resonance energy transfer readings indicated that the MC4 receptor exists as a constitutive homodimer, which was not regulated by peptide interaction. The efficiency of MC4 receptor to form homodimers was greatly enhanced compared to its ability to heterodimerize with the kappa opioid receptor.