GLP Peptides Compared: SM1, TZ2, RT3 & Cagri
Four long-acting peptides frequently discussed in incretin and amylin research are often mentioned in the same breath, yet each engages a different set of receptors. This reference compares them side by side for anyone organizing research materials — receptor targets, peptide class, reported half-life, structural basis, and handling. It makes no efficacy claims and is intended solely as a handling and characterization reference. All Heritage Labs compounds are for laboratory research use only and are not for human or veterinary use.
Receptor targets at a glance
| Attribute | SM1 | TZ2 | RT3 | Cagri |
|---|---|---|---|---|
| Receptor target(s) | GLP-1 receptor single incretin agonist | GLP-1 + GIP dual incretin agonist | GLP-1 + GIP + glucagon triple incretin agonist | Amylin receptors calcitonin receptor + RAMPs; separate pathway |
| Peptide class | GLP-1 analog | GIP-based GLP-1/GIP co-agonist | Engineered GLP-1/GIP/glucagon hybrid | Long-acting amylin analog |
| Reported plasma half-lifeapprox., from published research | ~7 days ~165 h | ~5 days ~120 h | ~6 days ~144–160 h | ~7–8 days ~180 h |
| Structural basis | GLP-1 backbone with C18 fatty-acid acylation for albumin binding | GIP-sequence backbone engineered for dual GLP-1/GIP activity; acylated | Hybrid sequence balancing three receptor activities; acylated | Amylin-derived sequence, acylated for extended half-life |
| Typical appearanceas listed; may vary | White to off-white lyophilized material | |||
| Handling & storage | Solvent, concentration, temperature, and storage should follow the product-specific documentation and your laboratory protocol; minimize unnecessary freeze–thaw cycles. See storage & handling. | |||
| Purity testing | Third-party HPLC tested for purity. See how HPLC works and how to read a COA. | |||
Half-life figures are approximate values reported in the peer-reviewed literature and vary by study and assay; they are provided for characterization/handling reference only.
Receptor pharmacology
The defining difference between these peptides is which receptors each one activates. The incretin group works along the GLP-1/GIP/glucagon axis; Cagri sits in a separate amylin pathway, which is why it is frequently studied alongside — not in place of — a GLP-1 agonist.
- SM1 — a selective GLP-1 receptor agonist; a useful single-receptor comparator in incretin research.
- TZ2 — adds GIP-receptor activity to GLP-1 activity (a dual agonist), built on a GIP-derived backbone.
- RT3 — adds glucagon-receptor activity on top of GLP-1 and GIP (a triple agonist), balancing all three in one sequence.
- Cagri — a long-acting amylin analog acting through amylin receptors, a separate pathway; the basis for research examining Cagri and SM1 together.
“More receptors” is not a potency ranking — it changes the pharmacology being studied. Comparisons may help researchers examine differences associated with receptor coverage, but results cannot be attributed solely to the number of receptor targets — the compounds also differ structurally and pharmacologically.
Structure & stability
All four are acylated (fatty-acid–modified) peptides. The acyl chain promotes reversible albumin binding, which is the main reason their reported half-lives land in the multi-day range rather than the minutes-to-hours range of the native hormones. They are typically supplied as lyophilized material; stability in solution depends far more on temperature, light exposure, and freeze–thaw handling than on which receptor the peptide targets.
Laboratory handling
Solvent selection, concentration, handling, and storage conditions should be determined by the applicable laboratory protocol and the product-specific documentation. Avoid repeated freeze–thaw cycles unless the experimental method requires otherwise. Do not assume one preparation method is interchangeable across all four compounds.
Related handling guides: How to reconstitute peptides · Bacteriostatic water · Storage & shelf life
Available at Heritage
Heritage Labs stocks each of these as third-party HPLC-tested research material, in a range of vial sizes:
- SM1 — 5 mg, 10 mg
- TZ2 — 5 mg, 10 mg, 20 mg, 30 mg, 60 mg
- RT3 — 5 mg, 10 mg, 20 mg, 30 mg, 60 mg (RT-3 60mg)
- Cagri — 5 mg, plus the Cagri/SM1 blend
Key takeaways
- The four differ primarily by receptor coverage: GLP-1 (SM1) → GLP-1+GIP (TZ2) → GLP-1+GIP+glucagon (RT3); Cagri is a separate amylin pathway.
- Reported half-lives all fall in the multi-day range because all four are acylated, albumin-binding peptides.
- They share general handling considerations for long-acting acylated peptides, but preparation and storage should be confirmed for each compound and experimental protocol.