Tirzepatide is a synthetic 39-residue lipidated peptide that acts as an agonist at two class B1 G protein-coupled receptors, the GIP receptor (GIPR) and the GLP-1 receptor (GLP-1R). Its backbone is derived from the glucose-dependent insulinotropic polypeptide sequence, modified so that it engages both incretin receptors from one molecule, and it is used as a reference agonist in cAMP accumulation, receptor binding and beta-arrestin recruitment assays. NuVion supplies Tirzepatide as a laboratory chemical for in vitro research use only.
Key facts
| Type / class | Synthetic lipidated peptide, dual GIPR and GLP-1R agonist |
| Amino acid count | 39 residues, C-terminal amide |
| Modifications | Aib at positions 2 and 13; Lys20 conjugated to a C20 fatty diacid through a gamma-glutamate and two AEEA spacers |
| Molecular formula | C225H348N48O68 |
| Molecular weight | Approximately 4,813 g/mol |
| CAS number | 2023788-19-2 |
| Synonyms / other names | LY3298176, dual GIP and GLP-1 receptor agonist |
| Supplied form | Lyophilised powder in a sealed vial |
Tirzepatide
From $89 AUD
View productResearch use only. Not for human or veterinary use.
Structure and chemistry
The peptide is built on the GIP scaffold. Native GIP and native GLP-1 share limited sequence identity, and their receptors read overlapping but distinct N-terminal determinants. Tirzepatide takes the GIP sequence and substitutes residues at the positions where GLP-1R contacts its own ligand, producing a single chain that both receptors accept.
Three modifications carry the design. Alpha-aminoisobutyric acid (Aib), a non-proteinogenic residue with two methyl groups on the alpha carbon, sits at position 2 and at position 13. Aib at position 2 blocks dipeptidyl peptidase-4, which otherwise cleaves the Tyr-Ala bond at the N-terminus of both native incretins and destroys their receptor activity, and the quaternary alpha carbon also biases the local backbone toward a helical conformation. The C-terminus is amidated, removing the terminal negative charge. The lysine at position 20 carries a C20 fatty diacid attached through a gamma-glutamate spacer and two units of AEEA, a short polyethylene-glycol-like linker. That acyl group binds reversibly to serum albumin, so in serum-containing media a large fraction of the peptide is albumin-associated and the free concentration is lower than the nominal one, which is worth accounting for when comparing potency values across assay formats.
There is no cysteine and no disulfide bond. The molecule is amphipathic: a helical mid-section, several hydrophobic residues (Phe, Trp, Leu, Ile) and a long lipid chain, with a proline-rich C-terminal segment. The acyl chain makes it prone to self-association and to adsorption onto plastic and glass, and it is the reason the peptide dissolves more readily in slightly alkaline buffer than in plain water.
Mechanism of action
GIPR and GLP-1R are both class B1 (secretin-family) GPCRs. Each has a large extracellular domain that captures the C-terminal half of the peptide ligand, after which the N-terminal residues insert into the transmembrane bundle and drive the conformational change that couples the receptor to Gs. The activated Gs alpha subunit stimulates adenylate cyclase, cAMP rises, and cAMP acts on two effectors: protein kinase A, which phosphorylates CREB and other substrates, and Epac2, a guanine nucleotide exchange factor for Rap1 that participates in the exocytotic machinery. In beta-cell lines, that cascade raises intracellular calcium and increases glucose-stimulated insulin exocytosis, which is the standard cellular readout for both receptors.
Tirzepatide engages the two receptors unequally. In binding and cAMP assays on cells expressing each receptor separately, its affinity and potency at GIPR are close to those of native GIP, while at GLP-1R it is weaker than native GLP-1 by roughly an order of magnitude. The compound is therefore described as an imbalanced or GIPR-preferring dual agonist, and that imbalance is why it is used as a probe: running it alongside a GIP-selective and a GLP-1-selective agonist in the same assay lets the contributions of each receptor be separated.
Its behaviour at GLP-1R is also biased. Tirzepatide produces a full cAMP response at that receptor while recruiting beta-arrestin poorly, so GRK-mediated desensitisation and receptor internalisation are weaker than with native GLP-1 or with a balanced agonist. More receptor stays at the cell surface through a prolonged exposure, and the cAMP signal is sustained where a balanced agonist’s signal decays. Bias of this kind is quantified by comparing cAMP and beta-arrestin concentration-response curves with an operational model, and tirzepatide is one of the standard reference compounds in that analysis. Cryo-EM structures of tirzepatide-bound GIPR-Gs and GLP-1R-Gs complexes show how one peptide fits both binding pockets.
Research applications
Tirzepatide sits in the NuVion Metabolism category. Typical study contexts include:
- cAMP accumulation assays (HTRF or GloSensor) in HEK293 or CHO lines expressing GIPR or GLP-1R separately, giving matched potency values at the two receptors.
- Competition binding against radiolabelled or fluorescent GIP and GLP-1 analogues on membrane preparations from receptor-expressing cells.
- Beta-arrestin recruitment and receptor internalisation assays, used with the cAMP data to quantify signalling bias at GLP-1R.
- Glucose-stimulated insulin secretion assays in beta-cell lines such as INS-1 832/13, with receptor antagonists or knockdown used to assign the response to one receptor or the other.
- Structural work: cryo-EM and hydrogen-deuterium exchange mass spectrometry on peptide-receptor-G protein complexes.
- Analytical method development, where the lipid chain and the two Aib residues determine RP-HPLC retention and the fragmentation pattern in LC-MS/MS.
Handling in the laboratory
Tirzepatide is supplied as a lyophilised powder in a sealed vial. It is reconstituted with bacteriostatic water, added gently down the vial wall and left to dissolve without shaking; the reconstitution calculator gives the volume needed for a target concentration. Lipidated peptides dissolve more slowly than unmodified ones and can leave a faint haze at high concentration, which usually clears on standing. Keep the sealed vial dry, away from light and refrigerated as described in the product documentation. Keep the reconstituted solution refrigerated and use it within the period stated in the documentation, aliquot it to avoid repeated freeze-thaw cycles, and use low-binding labware, since the acyl chain makes adsorptive loss at low concentrations a real source of error.
The peptide is characterised by RP-HPLC for purity and by mass spectrometry for identity. At roughly 4.8 kDa it gives a multiply charged electrospray envelope, and the deconvoluted mass confirms both the peptide chain and the intact acyl side chain, which is the modification most likely to be incomplete in a poorly made batch.
Testing and supply from NuVion
NuVion has Tirzepatide independently tested by Janoshik Analytical. Most batches are tested, and the Certificate of Analysis for a tested batch, showing RP-HPLC purity and mass spectrometry identity, is published on the product page and in the Certificates of Analysis library. Manufacture is GMP-audited, the peptide is supplied lyophilised in sealed vials, and orders are dispatched from within Australia.
Related compounds
In the same category, Retatrutide adds glucagon receptor activity to the same two incretin receptors and is the usual comparator in multi-receptor pharmacology, while 5-Amino-1MQ is a small-molecule enzyme inhibitor studied in the same metabolic pathways.
Frequently asked questions
What is Tirzepatide used for in research?
It is used as a reference dual agonist in incretin receptor pharmacology. Common work includes cAMP accumulation assays at GIPR and GLP-1R, competition binding, beta-arrestin recruitment assays that quantify signalling bias, and glucose-stimulated insulin secretion assays in beta-cell lines.
Why does Tirzepatide carry a fatty acid chain?
The C20 diacid on Lys20, linked through a gamma-glutamate and two AEEA spacers, binds reversibly to serum albumin. In the laboratory this changes the free peptide concentration in serum-containing media and affects adsorption to labware, so albumin content is one of the variables to hold constant when comparing potency values between assays.
Is Tirzepatide a therapeutic good in Australia?
The material NuVion supplies is not included in the Australian Register of Therapeutic Goods and has not been assessed by the TGA. It is a laboratory chemical for in vitro research, and nothing on this page is a representation about therapeutic use.
How should Tirzepatide be stored?
Keep the sealed vial of lyophilised powder dry, away from light and refrigerated as stated in the product documentation. After reconstitution, keep the solution refrigerated and use it within the period the documentation states. Aliquoting avoids repeated freeze-thaw cycles, which matter more for a lipidated peptide because aggregation is concentrated at the freeze front.
Research use only. This product is a laboratory chemical supplied for in vitro research. It is not included in the Australian Register of Therapeutic Goods and has not been assessed by the Therapeutic Goods Administration for quality, safety or efficacy. It is not for human or veterinary use, and nothing on this page is a representation about therapeutic use.
