Palmitoylation of the rat μ opioid receptor

Publisher Website
Google Scholar
Abstract
We examined whether the μ opioid receptor was palmitoylated and attempted to determine sites of palmitoylation. Following metabolic labeling with [3H]palmitic acid and immunoaffinity purification of the μ opioid receptor, SDS‐PAGE and fluorography revealed a broad labeled band with M r of ∼80 kDa in CHO cells stably expressing the rat μ receptor, but not in CHO cells transfected with the vector alone, indicating that the μ receptor is palmitoylated. Activation of the receptor with morphine did not affect the extent of palmitoylation. Hydroxylamine or dithiothreitol treatment removed most of the radioactivity, demonstrating that [3H]palmitic acid is incorporated into Cys residue(s) via thioester bond(s). Surprisingly, mutations of the only two Cys residues in the C‐terminal domain did not reduce [3H]palmitic acid incorporation significantly. Thus, unlike many G‐protein coupled receptors, the palmitoylation site(s) of the rat μ opioid receptor do(es) not reside in the C‐terminal domain.