In vitro studies have shown that (α4β2)2α5 receptors that differed only by the asparagine 398 amino acid displayed altered response to nicotine agonist compared with receptors containing aspartic acid.109 Further studies showed that Asn398 lowers Ca permeability and increases short-term desensitization in (α4β2)2α5, but does not alter the receptor sensitivity to activation.110
