Stabilization of high-affinity opioid agonist binding in neural cell membranes rigidified by cholesterol

Abstract

Incorporation of cholesteryl hemisuccinate (CHS) into membranes from SH-SY5Y human neural cells increased membrane microviscosity at both surface and core. In the rigidified membranes, [mu]-selective opioid agonists bound to a high-affinity state of the receptor similar to that observed upon receptor-G protein coupling. However, the high affinity state in rigidified membranes was unaltered by guanine nucleotides and pertussis toxin (PTX), and was not regulated by sodium. In contrast, the binding of opioid antagonists was insensitive to the membrane modification.