GLP-1, GIP and Glucagon: What the Receptor Names Mean
GLP-1, GIP and glucagon are three hormones the body already makes, and each has its own receptor, a docking point on a cell. An agonist is a molecule that switches one on: a single agonist reaches one receptor, a dual agonist two, and retatrutide all three. A receptor count is a fact, not a score. Supplied for in vitro research purposes only.
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What Are GLP-1, GIP and Glucagon?
They are three naturally occurring signalling hormones. Each one has its own docking point on the surface of cells, called a receptor.
Think of a receptor as a lock and the hormone as the key. When the key turns, the cell does something.
The compounds in this group are man-made keys. What separates them is simply how many of these three locks each one can turn.
What Does “Agonist” Mean?
An agonist is a molecule that fits a receptor and switches it on. That is the whole meaning of the word.
So the labels you see on product pages are just counting:
- A single agonist switches on one receptor.
- A dual agonist switches on two.
- A triple agonist switches on three.
Importantly, a dual agonist is one molecule doing two jobs. It is not two compounds mixed together. That is worth holding onto when reading a label.
How Do the Main Compounds Differ?
| Compound | Receptors it switches on | How many |
|---|---|---|
| A single GLP-1 agonist | GLP-1 | One |
| Tirzepatide | GLP-1 and GIP | Two |
| Retatrutide | GLP-1, GIP and glucagon | Three |
Reading down the middle column is the whole comparison. Everything else about these three molecules is detail on top of that.
What Evidence Sits Behind Each One?
Tirzepatide and retatrutide each carry a different kind of evidence behind them, and the table below says which. Receptor targeting is a fact about a molecule; what a trial measured is a fact about a formulation, and those are not the same claim.
| Compound | Receptors it is described as switching on | Evidence described on this site | Where that evidence stops |
|---|---|---|---|
| Tirzepatide | A dual agonist. It switches on the GIP and GLP-1 receptors | None. ARP does not list tirzepatide and publishes no guide to it. It appears here only as the worked example of what a dual agonist is. | A compound ARP does not supply has no ARP batch record standing behind it, and nothing here is an offer to supply one. Two receptors is a count, not a ranking. |
| Retatrutide | A triple agonist. It switches on the GIP, GLP-1 and glucagon receptors | Retatrutide: receptor targets and published research holds the published summary, and it is kept current there rather than repeated on this page | Reaching a third receptor is a fact about the molecule and not a result. Published research describes the formulation it studied, and this site publishes no comparison between the three |
What Does Acylation Mean on a Peptide?
The natural hormones these molecules are modelled on are short, unmodified peptides. The synthetic versions all carry the same extra piece of structure.
A fatty acid chain is attached to the peptide backbone. That chain binds reversibly to albumin, the most abundant plasma protein, and albumin binding is one of the standard properties measured for an acylated peptide in the laboratory.
The technical name for adding that chain is acylation, and you will see it on product pages. It has nothing to do with which receptors a compound binds — it describes a change to the molecule’s structure, not to its receptor targets.
Does Hitting More Receptors Mean Better?
No. A receptor count is a fact about a molecule, not a score.
Counting receptors tells you what a compound binds to. It does not tell you what happens afterwards, and those are separate questions. What engaging a third receptor actually leads to is still the subject of published research rather than a settled answer.
ARP publishes no comparison of results between these compounds and no guidance on using them. What is on the product pages is identity, receptor information, format, testing and where the material came from. The reasoning behind that boundary is set out under in vitro research requirements.
Common Questions
The number of receptors they switch on. Tirzepatide switches on two, GLP-1 and GIP. Retatrutide switches on those two plus a third, the glucagon receptor. They are separate molecules, and ARP publishes no comparison of results between them.
One molecule that switches on two different receptors at once. The important part is that it is a single compound doing both jobs, rather than two compounds blended together in one vial.
No. A GLP-1 receptor agonist is built on the shape of natural GLP-1 with deliberate changes made to it, which is what the word analogue means. One of those changes is the fatty acid chain attached to the backbone, which natural GLP-1 does not carry.
ARP supplies retatrutide to laboratories and researchers as freeze-dried research vials, alongside the rest of the catalogue. It is HPLC tested per batch, and the CoA library shows which certificates are published. All are supplied for in vitro research purposes only.
Related Guides
Receptor targeting is not abstract in this catalogue: Australian Research Peptides lists retatrutide, the triple agonist described above, for laboratories and researchers, in stock and with its own published certificate, and dispatches it from Sydney.
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