Kisspeptin-10: the decapeptide at the top of the reproductive axis

Kisspeptin-10 is one of the shorter members of the kisspeptin family, a set of peptides cut from a single precursor protein encoded by the KISS1 gene. That gene was first identified as a metastasis suppressor in melanoma cells, which is why its name has nothing to do with the biology it is now best known for. Only later did researchers work out that the peptides it produces are the natural ligands for an orphan G-protein-coupled receptor then called GPR54, now usually written KISS1R.

The number in the name is literal. Kisspeptin-10 is the C-terminal ten amino acids of the longer kisspeptin-54, and the family also includes fragments of 14 and 13 residues. All of them share the same active C-terminal tail, so the short decapeptide keeps the part of the molecule that actually engages the receptor. That is precisely why it became a convenient reference compound for laboratory work on KISS1R signalling: it is small, easy to synthesise, and biologically informative.

What the molecule is

The human sequence is Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe with a C-terminal amide, written YNWNSFGLRF-NH2 in single-letter code. The amide cap matters: the family belongs to the RFamide peptide class, and that terminal Arg-Phe-amide motif is central to receptor recognition. The rodent sequence differs from the human one, so studies specify which ortholog they used, and a compound sold for laboratory work should state the same. Verified identity values are listed further down this note.

As research chemicals go it is straightforward to make by solid-phase synthesis, and it is usually supplied as a lyophilised powder that is a salt of the free peptide. That salt form is why the mass on a batch certificate can differ from the free-base molecular weight quoted in a chemistry database, a distinction worth keeping straight when logging material.

The signalling researchers care about

KISS1R is a Gq/11-coupled receptor. When kisspeptin binds, it activates phospholipase C, which generates inositol trisphosphate and diacylglycerol and drives a rise in intracellular calcium. In the brain, the interesting population sits in the hypothalamus: kisspeptin neurons in the arcuate and anteroventral periventricular nuclei project onto neurons that release gonadotropin-releasing hormone (GnRH). Kisspeptin appears to be one of the strongest known activators of those GnRH neurons, which puts it near the top of the reproductive control hierarchy.

The genetics made the case hard to ignore. Loss-of-function changes in KISS1R were found in families who failed to progress through puberty, a condition called hypogonadotropic hypogonadism, while an activating change was linked to precocious puberty. That two-directional evidence, loss of signal delaying the reproductive axis and excess signal advancing it, is why kisspeptin is studied as a gatekeeper rather than a bit player.

What the preclinical record shows

In rodent and cell models, kisspeptin-10 depolarises GnRH neurons and, downstream, raises circulating luteinising hormone and follicle-stimulating hormone. Researchers use it to probe how the reproductive axis is switched on, how it is gated by metabolic and stress signals, and how continuous versus pulsatile exposure changes the response. That last point matters, because sustained receptor engagement tends to blunt the signal over time, a desensitisation pattern seen with many GPCR ligands.

As a small peptide with exposed termini, kisspeptin-10 does not persist long once in circulation, and the longer kisspeptin-54 is cleared more slowly. Work on modified analogues aims to slow that breakdown while keeping receptor selectivity, and comparing the short decapeptide against those analogues is a standard way to read out how much the added stability is worth.

Metabolic state feeds into this circuit. In animal models, signals such as leptin and the energy status of the organism modulate kisspeptin neuron activity, which is one proposed link between nutrition and reproductive function. Stress and sex-steroid feedback also converge on these neurons, so kisspeptin is often studied not in isolation but as an integrator that reports whether conditions are right for the reproductive axis to run.

Honest limitations

Most of the strongest data come from rodents and from cell lines engineered to express KISS1R, and the sequence differences between species mean results do not map one-to-one onto human biology. Receptor desensitisation complicates any model that relies on steady exposure. And while the reproductive neuroendocrinology is well supported, claims that reach beyond that axis are far thinner and should be read with caution. Kisspeptin-10 is a coming-soon product here. You can follow restock notifications on the kisspeptin-10 product page.

Verified molecule (human kisspeptin-10):

• Sequence: YNWNSFGLRF-NH2 (C-terminal amide)
• Molecular formula: C63H83N17O14
• Molecular weight: 1302.4 g/mol (free base)
• CAS number: 374675-21-5
• Class: RFamide peptide; ligand of KISS1R (GPR54)

For laboratory research use only. Not for human or veterinary use.

Common questions

Is kisspeptin-10 the same thing as kisspeptin-54?

No, but they are closely related. Kisspeptin-54 is the longer peptide produced from the KISS1 precursor, and kisspeptin-10 is its C-terminal ten residues. Because that C-terminal segment carries the receptor-binding motif, both engage KISS1R, but they differ in size and in how quickly each is cleared from solution and circulation in model systems.

Why do listings specify the human sequence?

Because the rodent and human kisspeptin sequences are not identical. A study or a data sheet that does not state the species leaves an ambiguity that matters for reproducing results, so reputable identity records name the ortholog. The verified values above are for the human decapeptide.

What receptor does it act on?

KISS1R, formerly named GPR54, a Gq/11-coupled G-protein-coupled receptor. Binding raises intracellular calcium through the phospholipase C pathway. In hypothalamic circuits this receptor sits upstream of GnRH neurons, which is the basis for most laboratory interest in the peptide.

References

1. Kotani M, et al. The metastasis suppressor gene KiSS-1 encodes kisspeptins, the natural ligands of the orphan G protein-coupled receptor GPR54. Journal of Biological Chemistry, 2001.
2. Ohtaki T, et al. Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G-protein-coupled receptor. Nature, 2001.
3. Seminara SB, et al. The GPR54 gene as a regulator of puberty. New England Journal of Medicine, 2003.