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Rat ghrelin is a 28-residue acylated peptide hormone and endogenous ligand of the growth hormone secretagogue receptor GHSR1a. Its defining structural feature is an n-octanoyl ester attached to Ser3, a modification required for strong activation of the canonical ghrelin receptor.
Originally isolated from rat stomach, this molecular form provides a species-matched ligand for studies of growth hormone secretion, hypothalamic signaling, feeding behavior and ghrelin receptor pharmacology in rodent systems.
Product Information
| Property | Specification |
|---|---|
| Product Name | Ghrelin, Rat |
| Catalog No. | AS2682 |
| CAS No. | 258338-12-4 |
| Sequence | Gly-Ser-Ser(n-octanoyl)-Phe-Leu-Ser-Pro-Glu-His-Gln-Lys-Ala-Gln-Gln-Arg-Lys-Glu-Ser-Lys-Lys-Pro-Pro-Ala-Lys-Leu-Gln-Pro-Arg |
| One-Letter Sequence | GS-S(n-octanoyl)-FLSPEHQKAQQRKESKKPPAKLQPR |
| Peptide Length | 28 amino-acid residues |
| Molecular Formula | C147H245N45O42 |
| Molecular Weight | Approximately 3314.79 Da |
| Key Modification | O-n-octanoylation at Ser3 |
| C-Terminus | Free carboxyl terminus |
| Primary Receptor | GHSR1a |
| Research Areas | Growth hormone secretion, feeding behavior, energy balance, neuroendocrine signaling |
Ser3 Octanoylation Defines the Receptor-Active Form
Ghrelin is unusual among peptide hormones because its receptor-active molecular form requires fatty-acid modification. The hydroxyl group of Ser3 carries an n-octanoyl chain, creating a hydrophobic feature that is critical for effective interaction with GHSR1a.
Removal of this acyl group produces des-acyl ghrelin, which has the same peptide backbone but greatly reduced ability to activate canonical GHSR1a signaling. Acyl ghrelin and des-acyl ghrelin should therefore be treated as distinct molecular entities in experimental design.
A Native Ligand for Rodent Ghrelin Receptor Studies
The discovery of rat ghrelin established a stomach-derived endocrine pathway capable of stimulating pituitary growth hormone release through a receptor system distinct from hypothalamic GHRH signaling.
GHSR1a is also expressed in neuroendocrine circuits involved in feeding and energy homeostasis. Rat ghrelin can therefore support experiments ranging from receptor-level calcium or signaling assays to pituitary, hypothalamic and whole-animal studies.
Rat and Human Ghrelin Are Closely Related but Not Identical
The first ten residues and the Ser3 octanoylation site are conserved between rat and human ghrelin. The principal sequence difference occurs at residues 11-12:
| Peptide | Residues 11-12 |
|---|---|
| Rat Ghrelin | Lys-Ala |
| Human Ghrelin | Arg-Val |
Researchers comparing species should therefore specify the exact ligand rather than using “ghrelin” as an interchangeable molecular designation.
The corresponding human sequence is available as Human Ghrelin.
Handling and Analytical Considerations
The Ser3 octanoyl group is an ester-linked modification and should be considered during sample preparation, storage and analytical characterization. Hydrolysis or incorrect acylation state can substantially alter receptor activity even when the peptide backbone remains intact.
For quantitative receptor or endocrine studies, we recommend confirming molecular mass together with chromatographic purity. Our Peptide Quality Control capabilities support analytical HPLC and mass spectrometry according to the selected specification.
Frequently Asked Questions
Where is rat ghrelin octanoylated?
The n-octanoyl group is attached to the hydroxyl group of Ser3.
Is des-acyl rat ghrelin the same material?
No. The amino-acid sequence is the same, but des-acyl ghrelin lacks the Ser3 fatty-acid modification and has substantially different canonical GHSR1a activity.
Can ghrelin acylation variants be synthesized?
Defined acyl-chain variants, des-acyl forms and sequence analogs can be evaluated through Chemical Peptide Synthesis.