Functional coupling of μ-receptor-Gαi-tethered proteins in AtT20 cells

Abstract

Opioid efficacy on μ-receptor may be influenced by various G i/o-G-protein subunits interacting with intracellular face of receptor. Pertussis toxin-insensitive Gαil; and G αi2 subunits tethered with μ-receptor were stably transfected into At T20 cells to (i) determine coupling of different α-subunits on opioid efficacy, and (ii) determine coupling to downstream effectors, for example, calcium and potassium channels. After pertussis toxin, stimulation of [35S]GTP-γ-S incorporation persisted. Both constructs were able to couple to native calcium and potassium channels, with endomorphins I and 2 equally effective. However, pertussis toxin abolished opioid actions on calcium and potassium chann..