Single, dual and triple receptor targets in lipidated peptides

The lipidated glucagon-family peptides are a single design lineage distinguished by how many receptors they engage: one, two or three. For a researcher reading the literature or characterising material, the differences that matter are structural and analytical, and the naming is a frequent source of confusion. This note compares the classes factually. Only the triple-receptor ligand, listed by Alphex as GLP-3 (RT), is in our catalogue, and it is supplied as a laboratory reagent. All Alphex products are for laboratory and in-vitro research only.

The shared design

All of these peptides are built on backbones from the glucagon superfamily (GLP-1, GIP, glucagon), modified in three consistent ways: substitution of protease-labile residues with non-natural ones such as alpha-aminoisobutyric acid (Aib) to resist enzymatic cleavage; attachment of a fatty acid or fatty diacid through a linker to a lysine side chain, promoting reversible albumin binding; and sequence engineering to tune receptor affinity. The lipidation is why the whole class is markedly less water-soluble and more prone to aggregation and plastic adsorption than short research peptides.

Receptor targets

• Single-receptor ligands: GLP-1 receptor only. Typically a GLP-1 backbone with Aib at position 8 and a C18 diacid, around 31 residues.
• Dual-receptor ligands: GIP and GLP-1 receptors. Typically a GIP-like backbone with a C20 diacid, engaging both receptors with differing relative potency.
• Triple-receptor ligands, listed by Alphex as GLP-3 (RT): GIP, GLP-1 and glucagon receptors. 39 residues, C20 diacid, CAS 2381089-83-2, 4731.3 g/mol. See the GLP-3 (RT) guide.

The receptor pharmacology of each class is documented in published in-vitro work, which is the appropriate primary source for relative potencies.

Naming, and why it confuses

A compound in this class can carry a development code, an INN, brand names for any authorised products, and various research-market names, and suppliers mix them freely. "Triple agonist", "dual agonist" and "GLP-3" are informal descriptors rather than formal nomenclature. Alphex uses "GLP-3 (RT)" as a catalogue name and states the CAS number, molecular formula and observed mass on the specification, so the identity of what is being supplied is fixed by analytical data rather than by a label. Research-grade material is not a pharmaceutical product, is not a medicine, and is supplied for laboratory use only. Background: peptide naming, INN codes and trade names.

Analytical and handling differences

• Size: 31 to 39 residues; all are large by research peptide standards, and all show a multiply-charged envelope in electrospray rather than a single ion. See mass spectrometry explained.
• Purity: reaching 99+% is genuinely difficult at this length with lipidation, and a certificate showing no minor peaks at all should raise questions rather than confidence. See 98% versus 99+%.
• Solubility: the whole class needs slow, gentle reconstitution, preferably into a mildly alkaline buffer; cloudiness means aggregation. See the solubility guide.
• Adsorption: the diacid binds plastic as readily as albumin; low-binding tubes for dilute solutions. See adsorption.
• Molar comparison: masses differ by hundreds of daltons, so mass-based comparisons between compounds are meaningless without conversion.

What Alphex supplies

GLP-3 (RT) only, in 5, 10, 20 and 30 mg vials, at 99+% HPLC purity (220 nm, reference standard), batch-numbered, UK stock, certificate available before purchase. Alphex does not stock the single- or dual-receptor peptides in this family. See why the catalogue is small.

Alphex research peptides are supplied for laboratory and in-vitro research by qualified researchers only. They are not authorised for human or veterinary use, and nothing here describes or recommends any such use.

Research use only. Alphex products are supplied exclusively for laboratory and in-vitro research by qualified researchers. They are not authorised for human or veterinary use, and nothing in this note is advice on any such use.

Published 28 July 2026, last reviewed 10 September 2026. Alphex reviews research notes when the testing method, the catalogue or UK guidance changes.

Alphex Research Team

Alphex Limited, UK research peptide supplier

The Alphex research team writes and maintains these notes for UK laboratories buying research peptides. Every batch Alphex lists is verified by reverse-phase HPLC and mass spectrometry with a batch-matched Certificate of Analysis. Content covers laboratory and in-vitro research only.