What Is PE-22-28? The Spadin-Derived Peptide

Cover illustration: AI-generated editorial artwork. Conceptual only; not an exact molecular structure, actual laboratory result or evidence of clinical effects.

PE-22-28 is a shortened analogue of spadin, itself a fragment of the sortilin propeptide. Its named target is the TREK-1 potassium channel. The compound is unusual in this category for having a well-documented and specific molecular target rather than a vaguely defined pathway.

For laboratory research use only. The research materials supplied by HealthyWelness are not approved medicines, foods or cosmetics and are not for human or veterinary use. This article summarises published research and is not medical advice.

Key points

Parent compound: spadin, described in PLoS Biology in 2010.
Origin of the sequence: the propeptide of sortilin (also known as neurotensin receptor 3).
Target: TREK-1, a two-pore-domain K+ channel.
Reason for shortening: better channel inhibition and improved in vivo stability.
Evidence base: electrophysiology and rodent models; no human data located.

Where the sequence comes from

Sortilin is synthesised with a propeptide that is cleaved off during maturation. Such propeptides are often treated as discarded by-products. The spadin work rests on the observation that this one is not inert: a fragment of it interacts with the TREK-1 channel.

That origin is worth noting because it is a different kind of discovery from most peptide research. Rather than truncating a known hormone to find its minimal active core, this line of work asked whether a cleaved propeptide has activity of its own. The 2019 review by Djillani and colleagues in Pharmacology and Therapeutics traces the history, and a companion 2019 paper examines sortilin’s own role and how it relates to TREK-1 membrane expression.

What TREK-1 is and why it is an interesting target

TREK-1 belongs to the two-pore-domain potassium channel family. These channels differ from the voltage-gated channels that dominate textbook accounts of excitability: they conduct a background potassium current that helps set resting membrane potential. A neuron’s resting potential determines how far it sits from firing threshold, so modulating a background K+ channel shifts excitability without being part of the action potential itself.

TREK-1 is also notable for its gating. It responds to mechanical stretch, to intracellular pH, to temperature and to polyunsaturated fatty acids including arachidonic acid. A 2020 study examined spadin’s interaction with the arachidonic acid activation pathway specifically, reporting selective antagonism of that mode. That degree of mechanistic resolution — not merely “blocks the channel”, but which activation route is affected — is rare in the research-peptide literature.

Why shortening the peptide helped

Property	Spadin (parent)	Shortened analogues
Length	Longer parent fragment	Shorter, including PE-22-28
TREK-1 inhibition	Established	Reported as better
In vivo stability	Limited	Reported as improved
Behavioural activity in rodents	Reported	Reported

The general principle: a longer peptide offers more protease cleavage sites. If the channel-interacting region is a subsegment, removing the rest can raise stability without losing activity. The 2017 Frontiers in Pharmacology paper is the primary reference for this specific result, and it is where the shortened analogues including PE-22-28 are characterised.

What the 2012 paper adds

Moha Ou Maati and colleagues examined whether spadin produced the effects one might expect from disrupting TREK-1 function, and reported their absence. Negative-finding papers of this kind are easy to overlook but carry real weight: a target-engagement claim becomes more credible when the predicted consequences of engaging that target have been looked for explicitly, whether or not they were found. In secondary summaries this nuance is usually lost, which is a reason to read the paper rather than a description of it.

Handling in the lab

Supplied lyophilized; store the sealed vial at −20 °C, protected from light and moisture.
Reconstitute gently — diluent down the vial wall, then swirl; do not vortex a short peptide into foam.
For electrophysiology, prepare fresh working dilutions in recording solution; peptides adsorb to perfusion tubing, so pre-rinsing the line with peptide-containing solution is common practice.
Aliquot stocks and keep working solutions at 2–8 °C. See storing reconstituted peptides.
Note that TREK-1 is lipid-sensitive: carrier additives and solvent vehicles can themselves affect channel activity, so vehicle controls matter more than usual here.
Concentration maths: peptide reconstitution calculator.

Our PE-22-28 research material is supplied with HPLC purity and MS identity data per lot.

Open questions

How selective are the shortened analogues for TREK-1 over the related TREK-2 and TRAAK channels?
Does the reported stability improvement hold across species and sample matrices?
What is the binding site on the channel, and does it overlap with the lipid activation site?

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Frequently asked questions

What is PE-22-28?

PE-22-28 is a shortened analogue of spadin, a peptide derived from the propeptide of sortilin. It is studied as an inhibitor of the TREK-1 two-pore-domain potassium channel in rodent systems.

What is spadin?

Spadin is a peptide corresponding to a fragment of the sortilin propeptide, first described in a 2010 PLoS Biology paper as targeting rodent TREK-1 channels. PE-22-28 comes from later work shortening that parent sequence.

What is TREK-1?

TREK-1 is a two-pore-domain potassium channel, mechanosensitive and sensitive to lipids including arachidonic acid. Potassium channels of this family set resting membrane potential and so influence neuronal excitability.

Why was a shorter analogue developed?

A 2017 study in Frontiers in Pharmacology reported that shortened spadin analogues showed better TREK-1 inhibition and improved in vivo stability than the parent peptide. Shortening a peptide can remove protease-susceptible regions while retaining the active core.

Has PE-22-28 been studied in humans?

No human trial was identified in our search. The published work on spadin and its analogues is in channel electrophysiology and rodent behavioural models.

References

Mazella J, et al. Spadin, a sortilin-derived peptide, targeting rodent TREK-1 channels: a new concept in the antidepressant drug design. PLoS Biol. 2010. PMID: 20405001 https://pubmed.ncbi.nlm.nih.gov/20405001/
Djillani A, et al. Shortened Spadin Analogs Display Better TREK-1 Inhibition, In Vivo Stability and Antidepressant Activity. Front Pharmacol. 2017. PMID: 28955242 https://pubmed.ncbi.nlm.nih.gov/28955242/
Djillani A, et al. Fighting against depression with TREK-1 blockers: Past and future. A focus on spadin. Pharmacol Ther. 2019. PMID: 30291907 https://pubmed.ncbi.nlm.nih.gov/30291907/
Moha Ou Maati H, et al. Spadin as a new antidepressant: absence of TREK-1-related side effects. Neuropharmacology. 2012. PMID: 21807005 https://pubmed.ncbi.nlm.nih.gov/21807005/