Overview

Tirzepatide is a synthetic analogue of gastric inhibitory polypeptide (GIP) that was developed for its ability to stimulate insulin release and thus address both type 2 diabetes and non-alcoholic fatty liver disease. Made up of 39 amino acids, the relatively large Tirzepatide stimulates the release of insulin from the pancreas by binding to both GIP and GLP-1 (glucagon-like peptide-1) receptors. Taken over longer periods of time, Tirzepatide increases adiponectin levels by as much as 26% as well.

Chemical Structure

Amino Acid Sequence: YE-Aib-GTFTSDYSI-Aib-LDKIAQ ^{(C20 fatty acid)} AFVQWLIAGGPSSGAPPPS
  Note: Aib is a non-coded (non-proteinogenic) amino acid – H₂H-C(CH₃)₂^–COOH
Molecular Formula: C₂₂₅H₃₄₈N₄₈O₆₈
Molecular Weight: 4813.527 g/mol
PubChem CID: 156588324
CAS Number: 2023788-19-2
Synonyms: P1206, LY3298176

Source: PubChem

Mechanism of Action

Tirzepatide is a single molecule that activates two distinct incretin receptors: the glucose-dependent insulinotropic polypeptide (GIP) receptor and the GLP-1 receptor. Native GIP and GLP-1 are gut hormones released after eating that amplify insulin secretion, but each is cleared within minutes by enzymes such as dipeptidyl peptidase-4 (DPP-4). Tirzepatide engages both receptors from one 39-amino-acid backbone while resisting that rapid clearance — the property that separates it from single-agonist peptides.

In receptor assays the molecule behaves as a biased agonist at the GLP-1 receptor, favoring cAMP signaling over beta-arrestin recruitment, and as a full agonist at the GIP receptor [1]. The consequence seen in tissue and animal work is additive signaling: GIP-receptor engagement appears to improve insulin sensitivity and adipocyte lipid handling, while GLP-1-receptor engagement drives glucose-dependent insulin release, slows gastric emptying, and reduces appetite through central pathways. Researchers study the two-receptor combination precisely because the effects are complementary rather than redundant.

Structure and Stability

The sequence carries two alpha-aminoisobutyric acid (Aib) residues at positions that block DPP-4 and neprilysin cleavage, plus a C20 fatty-diacid acyl chain that binds serum albumin. Albumin binding is why the peptide persists for days rather than minutes in circulation — a property researchers reproduce in vitro by adding albumin to assay buffers. The Aib substitutions and the acyl chain together account for most of the molecule’s departure from native GIP.

Research Program and Key Findings

Because tirzepatide is an approved therapeutic in several markets (Mounjaro, Zepbound), an unusually large public literature exists for a peptide of this class, and it is the reference point for most incretin research today. In the SURPASS head-to-head program in type 2 diabetes, tirzepatide produced greater reductions in HbA1c and body weight than semaglutide 1 mg at every compared dose [2]. In SURMOUNT-1, mean weight loss approached 21–22% of baseline body weight at the highest dose over 72 weeks, with a substantial share of participants exceeding 25% loss [3]. Separate analyses reported adiponectin rising roughly a quarter from baseline — consistent with improved adipose-tissue insulin sensitivity — alongside reductions in liver fat that keep tirzepatide an active subject in MASH research.

For laboratory work the peptide is handled as a lyophilized powder, reconstituted in bacteriostatic water or dilute acetic acid, aliquoted, and stored frozen to limit freeze-thaw cycles. As with all materials on this site, it is supplied for in-vitro and analytical research only.

References

[1] Willard FS, et al. Tirzepatide is an asymmetric dual GIP/GLP-1 receptor agonist. JCI Insight. 2020.
[2] Frías J, et al. Tirzepatide versus semaglutide once weekly in type 2 diabetes (SURPASS-2). Lancet. 2021.
[3] Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022.

Related Product: Tirzepatide — for laboratory research use only.