Met5-Enkephalin-Arg6,Phe7

Met5-Enkephalin-Arg6,Phe7, also known as MEAP, is an endogenous opioid peptide that is derived from the proenkephalin A precursor. It is a heptapeptide with the amino acid sequence Tyr-Gly-Gly-Phe-Met-Arg-Phe. This peptide is part of the enkephalin family, which are peptides that bind to opioid receptors and have roles in modulating pain and other physiological functions.

Structure and Function

Met5-Enkephalin-Arg6,Phe7 is an extension of the more common enkephalin peptides, which typically consist of five amino acids. The addition of the Arg6 and Phe7 residues distinguishes it from the pentapeptide Met-enkephalin. This extension can influence the peptide's affinity and selectivity for different opioid receptors, such as the mu-opioid receptor, delta-opioid receptor, and kappa-opioid receptor.

Opioid Receptors

Opioid receptors are a group of G-protein-coupled receptors with opioids as ligands. The primary classes of opioid receptors are:

• Mu-opioid receptor (MOR): Responsible for the analgesic effects of opioids and also associated with euphoria and respiratory depression.
• Delta-opioid receptor (DOR): Involved in modulating mood and may have a role in analgesia.
• Kappa-opioid receptor (KOR): Associated with dysphoria and psychotomimetic effects, but also analgesia.

Met5-Enkephalin-Arg6,Phe7 can interact with these receptors, potentially influencing pain perception, mood, and other physiological processes.

Biosynthesis

Met5-Enkephalin-Arg6,Phe7 is synthesized from the proenkephalin precursor, which is a large polypeptide that undergoes proteolytic cleavage to produce several active opioid peptides, including Met-enkephalin, Leu-enkephalin, and their extended forms like Met5-Enkephalin-Arg6,Phe7.

Physiological Role

The physiological role of Met5-Enkephalin-Arg6,Phe7 is not as well characterized as the more common enkephalins, but it is believed to play a role in modulating pain and possibly other functions such as immune response and stress.

Research and Clinical Implications

Research into Met5-Enkephalin-Arg6,Phe7 and other opioid peptides continues to be an important area of study, particularly in understanding pain mechanisms and developing new analgesic drugs that can provide pain relief without the side effects associated with traditional opioids.

Also see

• Enkephalin
• Opioid receptor
• Proenkephalin
• Endorphin
• Dynorphin