Opioid Peptide (OP)

Opioid peptides are short sequences of amino acids that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Opioid peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but they all resemble opiates. Brain opioid peptide systems are known to play an important role in motivation, emotion, attachment behaviour, the response to stress and pain, and the control of food intake. Opioid-like peptides may also be absorbed from partially digested food , but have limited physiological activity. The opioid food peptides have lengths of typically 4-8 amino acids. The body's own opioids are generally much longer. The human genome contains three homologous genes that are known to code for endogenous opioid peptides. Each gene codes for a large protein that can be processed to yield smaller peptides that have opiate-like activity.