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Kisspeptin is an endogenous neuropeptide family encoded by the KISS1 gene, with biologically active isoforms that function as endogenous ligands of the G-protein-coupled kisspeptin receptor (KISS1R).
Kisspeptin is a group of endogenous peptide derivatives obtained from the KISS1 precursor protein. The human KISS1 gene produces a precursor consisting of 145 amino acids, which is then cleaved by proteolytic action to yield a number of related peptides, mainly kisspeptin-54 (KP-54), as well as shorter fragments such as KP-14, KP-13 and KP-10. These peptides have in common a conserved C-terminal Arg-Phe-amide (RFamide) sequence, this sequence being an important structural characteristic of the kisspeptin family.
Most laboratory research has focused on kisspeptins in their capacity as endogenous ligands of the kisspeptin receptor (KISS1R), which has been known historically as GPR54. This receptor is a G protein-coupled receptor (GPCR), and experimental studies have looked into peptide–receptor recognition, receptor activation, and the related intracellular signalling.
From the point of view of molecular research, kisspeptin is studied as a system for investigating KISS1R pharmacology, the relationship between peptide structure and activity, and signalling associated with GPCRs. The conserved C-terminal region, especially that represented by kisspeptin-10, has been widely studied in structural and receptor-binding research.
Kisspeptin is a group of peptides derived from KISS1, and therefore the molecular features of kisspeptin vary according to the particular form under investigation. In humans, the KISS1 gene produces a precursor consisting of 145 amino acids, from which kisspeptin-54 (KP-54) is formed. Other shorter forms are KP-14, KP-13 and KP-10.
A characteristic structural feature of all human kisspeptins is the presence of the conserved C-terminal Arg-Phe-amide (RF-NH₂) motif. The common C-terminal decapeptide, kisspeptin-10, has the amino acid sequence Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH₂ and corresponds to the conserved receptor-recognition region which is found in the longer forms of kisspeptin.
Structural studies show that the C-terminal region plays a particularly important role in molecular recognition by KISS1R, the RF-amide motif establishing specific interactions within the receptor-binding pocket.
Kisspeptin has mainly been studied as an endogenous ligand of the kisspeptin receptor (KISS1R), which was previously called GPR54. KISS1R is a G-protein-coupled receptor (GPCR) and thus offers a well-defined molecular system for the investigation of peptide–receptor recognition and intracellular signal transduction.
KISS1R Receptor Activation
The binding of kisspeptin to KISS1R is mainly linked to signaling via Gαq/11. This in turn activates phospholipase C (PLC), causing it to promote the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP₂) and leading to the formation of the intracellular second messengers inositol trisphosphate (IP₃) and diacylglycerol (DAG).
Calcium and Protein Kinase Signaling
The signaling associated with IP₃ can induce the release of intracellular Ca²⁺ whereas DAG activates protein kinase C (PKC). These methods provide measurable biochemical endpoints for investigating KISS1R activation in receptor-expression and cell-based laboratory systems.
Downstream Molecular Pathways
Research on KISS1R has also investigated signaling cascades involving ERK1/2 and p38 MAPK along with pathways associated with β-arrestin signaling. Studies have further examined β-arrestin recruitment in relation to receptor desensitization and internalization following ligand activation.
Peptide–Receptor Recognition
Various fragments of kisspeptin, such as KP-54 and KP-10, still have the C-terminal region which is associated with recognition by KISS1R. Because of this the kisspeptin system is useful for carrying out comparative structure–activity and receptor-binding research in which the influence of peptide length and structural modifications on molecular interactions is examined.
This summary reflects findings reported in published preclinical and in vitro research. The original studies supporting this information are listed in the references.
Kisspeptins have been thoroughly studied as endogenous ligands of the kisspeptin receptor (KISS1R/GPR54). Experimental systems have been developed using receptor expression and binding studies in order to investigate ligand recognition, receptor activation, and the molecular pharmacology of the various kisspeptin fragments.
Studies into the structure have looked at the way kisspeptin interacts with the KISS1R binding pocket. More recent research using cryo-electron microscopy has examined complexes of KISS1R containing KP-10 and KP-54, giving molecular-level information regarding peptide recognition and receptor conformation.
Research based on cells has looked into the signalling that occurs after KISS1R is activated, with a particular focus on the Gq/11-associated phospholipase C signalling and the mobilisation of intracellular Ca²⁺. These pathways offer measurable biochemical endpoints for the characterisation of KISS1R activity under controlled experimental conditions.
The C-terminal region of kisspeptin has been the subject of extensive study in structure–activity relationship (SAR) research, and experiments in which amino acids were substituted in KP-10 have looked at how each residue affects receptor affinity, molecular conformation, and receptor-associated activity.
The KP-54, KP-14, KP-13 and KP-10 proteins have a conserved region at their C-terminus but vary in peptide length; it is therefore possible for comparative laboratory studies to look at how these structural differences affect molecular recognition and the characteristics associated with KISS1R.
KISS1R can also be used as a model for the study of G-protein coupling and for the structural biology of GPCRs. Recent structural and functional research has looked at its well-established coupling to Gq/11 together with evidence for additional Gi/o-associated signalling, thus giving further insight into the molecular organisation of the KISS1R signalling complexes.
Analytical verification of kisspeptin must confirm both its identity and its purity, and the specific form—for example, KP-10 or KP-54—should be clearly identified since each of these has a different molecular composition. Chromatographic purity can be determined using reverse-phase HPLC (RP-HPLC), this method also allowing the main peptide to be separated from related impurities or degradation products.
Molecular identification can be carried out using LC-MS or high-resolution mass spectrometry (HRMS) to confirm the expected molecular species; analytical research that has already been published shows that LC-HRMS and targeted MS/MS methods can be used for the characterisation of KP-10, KP-13, KP-14, and KP-54, including the employment of characteristic precursor and fragment ions for identification.
Mass spectrometry can also be used to identify peptide fragments and degradation products; for instance, analytical studies of KP-10 have found degradation linked to modification of its tryptophan residue.
Qualified laboratory personnel should handle Kisspeptin-10 using clean techniques that minimize contamination and protect material integrity.
Keep the product in its original, tightly closed container and store it according to the product specifications. The current product specification calls for storage at 2–8°C.
Protect the material from unnecessary exposure to moisture, light, air and temperature changes. Minimize the time the container remains open during handling. Use clean laboratory equipment and maintain appropriate storage conditions to help preserve the peptide quality and integrity.
Kisspeptins are endogenous peptides which occur naturally and are derived from the KISS1 precursor protein, and synthetic versions of specific kisspeptin fragments, for example KP-10 and KP-54, can likewise be produced for use in controlled laboratory research.
The main types of kisspeptin are KP-54, KP-14, KP-13 and KP-10. Although these peptides vary in length they have a conserved amidated C-terminal region which is responsible for their shared molecular features.
KP-54 consists of 54 amino acid residues, while KP-10 is the conserved 10-residue C-terminal fragment of the kisspeptin sequence. Although both peptides have the characteristic C-terminal Arg-Phe-NH₂ (RF-amide) motif, they are chemically different peptides and must be identified separately in analytical documentation.
The Arg-Phe-NH₂ sequence at the C-terminus of human kisspeptins is known as the RF-amide motif and is a structural feature that is shared by the active kisspeptin fragments; it also constitutes part of the molecular region that is involved in recognition of KISS1R.
Kisspeptin is an endogenous ligand of the kisspeptin receptor (KISS1R), which has been referred to previously as GPR54. The KISS1R is a G-protein-coupled receptor that is employed in experiments to study peptide–receptor recognition and the related molecular signalling.
Structural studies show that the conserved C-terminal area of kisspeptin, especially the RF-NH₂ motif, is important. Cryo-EM investigations indicate that this region forms a network of polar and hydrophobic interactions in the KISS1R binding pocket.
Research material containing kisspeptin can be characterised using techniques such as RP-HPLC, LC-MS and high-resolution mass spectrometry (HRMS). The mass-spectrometric methods are able to tell apart specific types, for example KP-10, KP-13, KP-14 and KP-54, on the basis of their molecular masses and their characteristic fragment ion
Kisspeptin peptide is not meant for human or animal administration, or veterinary use, nor is it supplied for any medicinal, diagnostic, or therapeutic use. It is solely available for use in laboratory research for scientific and analytical objectives.
The information given on this page is offered solely for scientific and technical reference purposes, covering molecular characteristics, analytical verification, KISS1R interactions and laboratory research. When references are made to receptor binding or molecular signalling pathways, this relates to areas that have been studied in scientific research and must not be understood as indicating any clinical effectiveness or as proof that the information is suitable for therapeutic use.
