Molecular aspects of delta opioid receptors.

The delta opioid receptor (DOP) belongs to the Class A, rhodopsin-like family of G protein-coupled receptors. Although this receptor has a high level of similarity with the other opioid receptors, it displays unique aspects and functions. Indeed, as opposed to most membrane receptors, DOP is poorly addressed to the plasma membrane. In this chapter, we first review the molecular and cellular mechanisms regulating the expression and the cellular trafficking/sorting of DOP. We then summarize the structural insights of this receptor through the analysis of the existing crystal structures, with a particular focus on the role of the sodium binding site. Finally, we review the current signaling mechanisms mediating receptor function and desensitization.