Single Amino Acid Variation Underlies Species-Specific Sensitivity to Amphibian Skin-Derived Opioid-like Peptides. Vardy E, Sassano MF, Rennekamp AJ, et al. Single Amino Acid Variation Underlies Species-Specific Sensitivity to Amphibian Skin-Derived Opioid-like Peptides. Chem Biol. 2015;22(6):764-75. doi:10.1016/j.chembiol.2015.05.012 Read more