Dynamic modelling of the binding of substances to the conserved membrane-adjacent heptapeptide of the 15-residue C-terminal cytoplasmic fragment of mammalian dopamine D2 receptors.

Dynamic modelling was carried out on the binding in water of several substances to the conserved membrane-adjacent heptapeptide of the 15-residue C-terminal cytoplasmic fragment (C-tail) of mammalian dopamine D2 receptors, PheAsnIleGluPheArgLys. Particularly important in the establishment of binding pockets for ligands were the carboxyl, phenyl, guanidino, and epsilon-amino groups of the last 4 residues. A broad array of chemical structures was found to be potentially capable of binding to this site, among which were dopamine, dopamine D2 receptor agonists and antagonists, GABA, muscimol, GABA(B) receptor agonists and antagonists, homocamosine, and carnosine. Since the C-tail is critical for G protein binding, it is suggested that many naturally-occurring and synthetic substances may be modulators of activation of G proteins by G-coupled receptors.