. "Combining with an enkephalin, and transmitting the signal across the membrane by activating an associated G-protein. A enkephalin is a pentapeptide (Tyr-Gly-Gly-Phe-Met or Tyr-Gly-Gly-Phe-Leu) involved in regulating nociception in the body." . . "delta-opioid receptor activity" . "enkephalin receptor activity" . .