What Is Retatrutide? Chemical Structure, Receptor Profile, and Laboratory Handling Reference

WARNING: LABORATORY RESEARCH USE ONLY. This material is synthesized and distributed strictly for B2B development, laboratory research, and analytical studies. It is not a drug, dietary supplement, or cosmetic. Under no circumstances is this chemical compound intended for human or veterinary diagnostic or therapeutic application. All research must be conducted by qualified laboratory personnel using appropriate safety controls.

Last reviewed: 2026-07-08 · Research use only.

Retatrutide (research designation LY3437943) is a synthetic 39–amino-acid peptide studied in molecular pharmacology as a single-molecule agonist of three distinct human hormone receptors. This page is the canonical chemical reference for Retatrutide: its verified specifications, in vitro receptor profile, and laboratory handling protocols for research personnel. For side-by-side chemistry against related peptides, see Retatrutide vs Tirzepatide vs Semaglutide.

1. Retatrutide Chemical Profile & Specifications

Retatrutide is a 39–amino-acid synthetic peptide bearing a C20 fatty-diacid moiety conjugated through a γ-glutamate / AEEA linker. When procuring reference material for laboratory assays, analytical purity is essential to reproducibility.

Note on reported formula and mass: published and vendor sources vary for this molecule. The commonly cited values are the formula C₂₂₁H₃₄₂N₄₆O₆₈ and a mass of ≈ 4731.33 Da, while some technical records list C₂₂₈H₃₅₀N₄₈O₆₆ (≈ 4894.58 Da). The difference typically reflects salt form / counterion and how the fatty-diacid linker is accounted for. Confirm against the batch-specific Certificate of Analysis (CoA) for the exact material received.

2. Molecular Pharmacodynamics: Triple Receptor Agonist Profile

In receptor-signaling assays, Retatrutide is classified as a unimolecular GIP, GLP-1, and glucagon (GCG) receptor tri-agonist, activating three human receptors in cell-based models.

                  ┌───► GIP receptor    (glucose-dependent insulinotropic polypeptide)
                  │
Retatrutide ──────┼───► GLP-1 receptor  (glucagon-like peptide-1)
                  │
                  └───► Glucagon receptor (GCGR)

(Figure: entity–receptor map. On the published page, replace with a labeled SVG carrying factual alt text for multimodal retrieval — see templates/_shared.md M8.)

In Vitro Receptor Potency (cAMP EC50)

Values reported by Coskun et al. (2022) in cyclic-AMP accumulation assays using cells expressing each human receptor:

• GIP receptor: EC50 ≈ 0.064 nM — the most potent of the three interactions.
• GLP-1 receptor: EC50 ≈ 0.775 nM.
• Glucagon receptor (GCGR): EC50 ≈ 5.79 nM.

This tri-agonist profile makes Retatrutide a subject of interest for laboratory study of multi-receptor signaling and downstream cAMP pathways in transfected cell lines. Its three-receptor selectivity is the key chemical distinction from dual-agonist (Tirzepatide) and mono-agonist (Semaglutide) peptides.

3. Laboratory Handling & Reconstitution Guidelines

To preserve the structural integrity of lyophilized Retatrutide during assay preparation, follow standard peptide-handling protocols.

Storage

• Long-term (lyophilized): store at -20°C or lower (e.g., -80°C); protect from moisture.
• Short-term (reconstituted): aliquot and store at 2–8°C for limited-duration use; freeze individual aliquots at -80°C and avoid repeated freeze-thaw cycles.

Reconstitution for in vitro assays

Prepare stock solutions using standard laboratory solvents — sterile water, deionized water, or phosphate-buffered saline (PBS).

1. Bring the vial to room temperature (≈ 20–22°C) before opening to prevent condensation.
2. Wipe the stopper with a sterile isopropyl-alcohol wipe.
3. Add solvent slowly, directing the stream down the inner glass wall of the vial rather than onto the powder cake.
4. Swirl gently until fully dissolved into a clear, colorless solution. Do not shake — agitation can cause peptide aggregation and denaturation.

4. HPLC Purity & Quality Verification

Analytical documentation confirms both purity and identity of a research peptide:

• HPLC: confirms purity >99.0% and the absence of synthesis byproducts / truncated-peptide impurities.
• Mass Spectrometry: confirms the measured mass matches the theoretical mass for the intended sequence and fatty-acid linker, verifying compound identity.

A batch-specific Certificate of Analysis (CoA) documents these results per lot. For how to evaluate a supplier and request lot-specific documentation, see the B2B sourcing & verification guide.

5. Frequently Asked Questions

Q: What is Retatrutide? A: Retatrutide (LY3437943) is a synthetic 39–amino-acid peptide that acts in vitro as a triple agonist of the human GIP, GLP-1, and glucagon receptors. It is a laboratory research reagent only.

Q: What is the CAS number of Retatrutide? A: The CAS registry number for Retatrutide (LY3437943) is 2381089-83-2.

Q: What receptors does Retatrutide target in vitro? A: It is a triple agonist of the human GIP, GLP-1, and glucagon (GCG) receptors, studied for laboratory research only.

Q: How should lyophilized Retatrutide be stored? A: Store lyophilized material at -20°C or lower for long-term stability; keep reconstituted aliquots at 2–8°C short-term and freeze aliquots at -80°C to avoid freeze-thaw degradation.

Q: Why do sources list different molecular weights for Retatrutide? A: Reported values (≈ 4731.33 Da vs ≈ 4894.58 Da) differ by salt form/counterion and how the fatty-diacid linker is accounted for; confirm against the CoA for the specific batch.

Q: What purity standard applies to research-grade Retatrutide? A: Reference-grade material is verified to >99.0% purity by HPLC with MS identity confirmation, documented on a batch-specific Certificate of Analysis.

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7. Scholarly References

1. Coskun, T., et al. (2022). LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: from discovery to clinical proof of concept. Cell Metabolism, 34(9), 1234–1247.e9. https://doi.org/10.1016/j.cmet.2022.07.013
2. National Center for Biotechnology Information. PubChem Compound Summary for Retatrutide. https://pubchem.ncbi.nlm.nih.gov/compound/Retatrutide
3. Jastreboff, A. M., et al. (2023). Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine, 389(6), 514–526. https://doi.org/10.1056/NEJMoa2301972 (cited strictly for historical context of the molecule's chemical development.)

Related references: Retatrutide vs Tirzepatide vs Semaglutide — receptor-selectivity comparison · How to source high-purity Retatrutide (B2B verification guide)

Disclaimer: Boss BioTech USA distributes chemical compounds solely for laboratory research and analytical development. All products, including Retatrutide, are not approved for human clinical use, diagnosis, prevention, treatment, or cure of any medical condition or disease. The purchaser assumes all risks associated with the handling, testing, and use of these materials.