RT3 research.

RT3 (LY3437943) is a synthetic 39-amino-acid peptide first characterised by Coskun and colleagues at Eli Lilly in 2022. It is the first clinically evaluated triple agonist to combine activity at the GLP-1, GIP and glucagon receptors within a single molecule, positioning it as a distinct pharmacological tool relative to established incretin comparators such as Tirz (dual GLP-1 / GIP) and Sema (single GLP-1).

In a laboratory research context, RT3 is used as a reference compound in receptor-binding, functional cAMP, β-arrestin recruitment and comparative agonist studies. Reproducibility of these assays depends on a well-characterised research-grade peptide: identity, purity and stability data must be documented on a per-batch basis and traceable to the vial in use. The full commercial supply framework is documented on the RT3 UK hub.

Interest in RT3 within research pharmacology reflects three converging factors: the addition of glucagon receptor activity to a GLP-1 / GIP backbone, the resulting distinct energy-balance profile observed in preclinical models, and its role as a reference triple agonist for structure-activity comparisons across the incretin class.

• Reference triple agonist for GLP-1 / GIP / glucagon receptor pharmacology.
• Comparator for structure-activity studies against dual and single incretin agonists.
• Model peptide for characterising long-acting fatty-acid-conjugated GLP-1 analogues.
• Reproducibility benchmark for in-vitro receptor and functional assays.

BuyRetaUK operates against the peptide-specific quality attributes described in USP General Chapter <1503> and the specification framework of ICH Q6A. Every batch is released to a formal specification before it enters inventory, and no vial is dispatched without a traceable Certificate of Analysis.

• Purity: ≥99% by HPLC-UV area-percent.
• Identity: Mass spectrometry confirmation against theoretical monoisotopic mass.
• Appearance: White to off-white lyophilised cake or powder.
• Endotoxin: Reported on batch COA where determined.
• Traceability: Batch number printed on vial matches the published COA exactly.

Research-grade RT3 is treated as a reference specimen within our range. Each batch passes an independent HPLC-UV purity check, mass-spec identity confirmation and visual appearance inspection before release. Batch-specific documentation is then published in our public verification library so any laboratory can cross-reference the vial in front of them.

Our full quality framework — release criteria, retained samples, stability monitoring and supplier qualification — is documented on the laboratory quality page.

A Certificate of Analysis (COA) is the primary quality record for a peptide batch. For RT3 it summarises the compound identity, batch number, manufacture date, purity method and result, mass-spec identity confirmation, appearance, and — where determined — endotoxin and moisture data.

Every batch of RT3 dispatched by BuyRetaUK is accompanied by a batch-specific COA. Read the full Certificate of Analysis guide for a section-by-section walkthrough, or open the verification library to cross-reference a specific batch number.

High-Performance Liquid Chromatography with UV detection (HPLC-UV) is the reference method for quantifying peptide purity. A sample is separated over a reverse-phase C18 column under a controlled acetonitrile / water gradient with trifluoroacetic acid modifier, and eluting peaks are integrated by area-percent at a peptide-bond absorbance wavelength (typically 214–220 nm).

A ≥99% HPLC-UV release means the main RT3 peak accounts for at least 99% of total integrated peak area. Impurity peaks — including truncated sequences, deletion products and oxidised variants — are visible and quantifiable, giving laboratories confidence that any signal observed in downstream assays reflects RT3 itself and not confounding species.

• Lyophilised vials: store at 2–8 °C, protected from light. For extended storage >3 months, hold at −20 °C.
• Reconstitution: add bacteriostatic water down the inside wall of the vial and swirl gently — do not shake or vortex.
• Working stock: keep refrigerated at 2–8 °C and use within 30 days; avoid repeated freeze-thaw cycles.
• Handling: aseptic technique in a laminar flow environment where the study protocol requires it.
• Volumes: use the reconstitution calculator to convert vial strength and target concentration to a diluent volume.