Other · Amidated opioid tetrapeptide
Endomorphin-1
Also known as EM-1
Amidated tetrapeptide used to investigate μ-opioid receptor selectivity, Gi/o signalling and enzymatic peptide breakdown.
- Length
- 4 amino acids
- Half-life
- Not well characterised
- Mechanism
- Endomorphin-1 is a selective agonist at the μ-opioid receptor (MOR; OPRM1), activating Gi/o-dependent signalling. In receptor-expressing systems, it inhibits adenylyl cyclase and modulates ion-channel activity, with signalling and internalisation profiles dependent on the assay context.
- Studied in
- Research uses recombinant MOR cell lines, isolated neural preparations and rodent models to investigate opioid receptor recognition, signalling, peptide degradation and sensory processing.
About Endomorphin-1
Endomorphin-1 has the sequence Tyr–Pro–Trp–Phe–NH₂, combining an N-terminal tyrosine with a C-terminal phenylalanine amide. It was reported in 1997 following isolation from bovine brain and showed high affinity and selectivity for the μ-opioid receptor. Unlike several established opioid peptide families, it has no conclusively identified precursor protein or fully established endogenous biosynthetic pathway, so its biological origin warrants careful qualification in reference material.
Laboratory studies use Endomorphin-1 to examine how a compact peptide engages MOR and couples receptor activation to intracellular responses. Common readouts include competitive ligand binding, inhibition of cyclic AMP accumulation, G-protein activation and receptor internalisation. Neural preparations and rodent experiments extend this work to synaptic signalling and sensory processing. Its tryptophan residue distinguishes it from Endomorphin-2 and provides a useful point of comparison in structure–activity studies.
Laboratory notes
- Confirm the C-terminal amide by mass spectrometry; the corresponding free acid is not chemically or pharmacologically equivalent.
- Protect solutions from strong light and oxidising conditions because the tryptophan residue can undergo chemical modification.
- Include receptor-negative controls and a selective MOR antagonist when assigning functional responses to MOR.
Storage and reconstitution basics: storage guide.
Questions about Endomorphin-1
How does Endomorphin-1 differ structurally from Endomorphin-2?
Endomorphin-1 contains tryptophan at position 3, whereas Endomorphin-2 contains phenylalanine; both are C-terminally amidated tetrapeptides.
Is its endogenous precursor established?
No conclusive precursor protein or complete biosynthetic pathway has been established, despite reports of isolation and endomorphin-like immunoreactivity in biological material.
Why is there no single reliable half-life value?
Degradation varies with species, biological matrix, peptidase activity and analytical method; stability should be measured in the intended experimental system.
Is Endomorphin-1 for human use?
No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.
Related research peptides
All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.