Other · Amidated neuropeptide; galanin-receptor ligand
Spexin
Also known as SPX; neuropeptide Q
A conserved, amidated 14-residue neuropeptide used to investigate GALR2/GALR3 signalling and neuroendocrine regulation.
- Length
- 14 amino acids
- Half-life
- Not well characterised
- Mechanism
- Spexin activates galanin receptors GALR2 and GALR3, with little or no activity at GALR1 in standard recombinant receptor assays. Downstream signalling depends on receptor subtype and cellular context, including phospholipase C-associated signalling through GALR2 and inhibitory G-protein signalling through GALR3.
- Studied in
- Recombinant receptor systems, neuronal preparations, fish models and rodent models are used to investigate spexin signalling, neuroendocrine regulation and energy-sensing pathways.
About Spexin
Spexin was identified in 2007 through computational screening for previously unrecognised peptide precursors in the human proteome. The mature mammalian peptide contains 14 amino acids and carries a C-terminal amide, generated during precursor processing. Its sequence is strongly conserved across vertebrates, making comparative studies in fish and mammals particularly informative. Spexin is encoded by the SPX gene and is distinct from galanin despite sharing two of its receptor targets.
Receptor-screening studies subsequently established GALR2 and GALR3 as spexin-responsive receptors. These are G-protein-coupled receptors, but their coupling and assay readouts differ: GALR2 commonly supports phospholipase C and calcium signalling, whereas GALR3 predominantly couples to inhibitory G proteins. Laboratory work examines receptor pharmacology, neuronal responses, endocrine signalling and metabolic gene regulation. Interpretation requires attention to species, receptor expression and peptide processing, since precursor abundance does not directly establish the concentration of mature, amidated spexin.
Laboratory notes
- Confirm C-terminal amidation and sequence identity by suitable analytical methods; a free-acid analogue is not chemically equivalent to mature spexin.
- Use receptor-defined GALR2 and GALR3 systems alongside appropriate negative controls when assigning receptor-dependent activity.
- Prepare aliquots under the supplier's validated storage conditions and minimise repeated freeze–thaw cycles; verify recovery where dilute solutions may adsorb to plastic.
Storage and reconstitution basics: storage guide.
Questions about Spexin
Does spexin activate every galanin receptor?
No. Established receptor profiling supports GALR2 and GALR3 activation, rather than appreciable GALR1 activation under comparable assay conditions.
Why is the C-terminal amide important?
Amidation is a defining feature of the mature peptide and can influence receptor recognition and biological activity. Assay comparisons should use a clearly specified terminal form.
Can SPX transcript measurements replace peptide measurements?
No. Transcript abundance does not resolve precursor cleavage, amidation or extracellular peptide availability. These materials are for research use only.
Is Spexin 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.