Probable G-protein coupled receptor implicated in a large repertoire of behavioral responses that engage motor activities, spatial learning, and emotional processing. May play a role in the regulation of cognitive and motor function. During cortical lamination, subcellular location shifts, on the day of birth, from expression at the plasma membrane and in the cytoplasm to the nuclei of neurons. This intranuclear localization remains throughout adulthood. Expressed predominantly in the striatum. Mice have increased locomotion, increased motor stereotypical behavior, and impaired motor skill learning. Mutant mice also show facilitated hippocampal-mediated behaviors and decreased anxiety. Chronic blockade of delta opioid receptors and mu opioid, but not other Gi/o coupled receptors, using delta opioid receptor antagonist partially improved motor coordination and normalized spatial navigation and anxiety of mutant mice. Belongs to the G-protein coupled receptor 1 family.