Disruption of the mu-delta opioid receptor heteromer

► Three glycines in the delta receptor carboxyl tail required to form heteromers. ► A delta receptor with any glycine substituted did not form heteromers. ► In mu receptor three cytoplasmic residues, -SVR, involved in forming heteromers. ► Each of the mu receptor residues, -SVR, were required to form heteromers. ► In delta receptor three cytoplasmic residues, -SVR, involved in forming heteromers.