Met-enkephalins compete with and mimic the effects of opiate drugs. They play a role in a number of physiologic functions, including pain perception and responses to stress. Enkephalin peptides found in Meiacanthus fangblennies induce physiological effects via their interaction with delta-type opioid receptors (OPRD1) (tested on M.grammistes). Therefore, finding a proenkephalin sequence in M.atrodorsalis venom suggests that this protein act in the same manner (Probable). Expressed by the venom gland. Moderately expressed in the venom gland transcriptome. In contrast to venom of most venomous species, the venom of Meiacanthus fangblennies is relatively painless, when tested on mammals. While species-specific nociceptive effects are possible, this defensive venom is surprisingly multifunctional, being markedly hypotensive (via neuropeptide Y and/ or enkephalins), weakly neurotoxic (unknown components, possibly PLA2s), and perhaps also pro-inflammatory (PLA2s and/or enkephalins). The pronounced hypotensive effects induced by venom peptides seem highly likely to affect the coordination and/or swim performance of envenomed fishes and therefore likely confer a fitness advantage to the fangblenny by facilitating escape from predators. Belongs to the opioid neuropeptide precursor family.