Palmitoylation of cysteine 415 of CB1 receptor affects ligand-stimulated internalization and selective interaction with membrane cholesterol and caveolin 1

We previously demonstrated that CB, receptor is palmitoylated at cysteine 415, and that such a post-translational modification affects its biological activity. To assess the molecular mechanisms responsible for modulation of CB, receptor function by S-palmitoylation, in this study biochemical and morphological approaches were paralleled with computational analyses. Molecular dynamics simulations suggested that this acyl chain stabilizes helix 8 as well as the interaction of CB, receptor with membrane cholesterol. In keeping with these in silico data, experimental results showed that the non-palmitoylated CB, receptor was unable to interact efficaciously with caveolin 1, independently of its activation state. Moreover, in contrast with the wild-type receptor, the lack of S-palmitoylation in the helix 8 made the mutant CB, receptor completely irresponsive to agonist-induced effects in terms of both lipid raft partitioning and receptor internalization. Overall, our results support the notion that palmitoylation of cysteine 415 modulates the conformational state of helix 8 and influences the interactions of CB, receptor with cholesterol and caveolin 1, suggesting that the palmitoyl chain may serve as a functional interface for CB, receptor localization and function. (C) 2017 Elsevier B.V. All rights reserved.