What is GLP-1?
Glucagon-like peptide-1 (GLP-1) is an endogenous incretin hormone secreted by L-cells of the distal small intestine and colon in response to nutrient intake. It is a 30-amino acid peptide cleaved from the proglucagon precursor by prohormone convertase 1/3.
GLP-1 has a very short half-life in vivo (~2 minutes) due to rapid degradation by dipeptidyl peptidase-4 (DPP-4), which has driven research interest in developing protease-resistant synthetic agonists for laboratory study.
The GLP-1 Receptor
The GLP-1 receptor (GLP-1R) is a class B G protein-coupled receptor (GPCR). Class B GPCRs are characterised by a large extracellular domain that participates in ligand binding and a seven-transmembrane helical core. GLP-1R is expressed in pancreatic beta cells, cardiac tissue, kidney, lung, and specific neuronal populations including the hypothalamus and brainstem.
Upon activation, GLP-1R primarily couples to Gs proteins, stimulating adenylyl cyclase and increasing intracellular cyclic AMP (cAMP), which potentiates glucose-stimulated insulin secretion. GLP-1R can also recruit beta-arrestin, mediating receptor internalisation and biased signalling pathways of independent research interest.
Biased agonism at GLP-1R — where different ligands preferentially activate G protein pathways over beta-arrestin recruitment, or vice versa — is an active area of receptor pharmacology research. This makes GLP-1R an important model system for studying GPCR signalling selectivity.
Classes of GLP-1 Receptor Agonists
Research-grade GLP-1 receptor agonists are typically classified by their structural basis:
- Peptide agonists — synthetic analogues of native GLP-1 with modifications conferring DPP-4 resistance and extended half-life. Examples used in research include semaglutide (a fatty-acid acylated GLP-1 analogue) and liraglutide.
- Dual agonists — compounds that co-activate GLP-1R alongside another receptor, most notably GIPR. Tirzepatide is the primary dual GLP-1/GIP agonist available for laboratory research.
- Triple agonists — compounds targeting GLP-1R, GIPR, and the glucagon receptor simultaneously. Retatrutide is the leading triple agonist compound in research use.
Incretin Biology: GLP-1 and GIP
GLP-1 and GIP together constitute the two principal incretin hormones, accounting for the majority of the incretin effect — the amplification of insulin secretion in response to oral nutrient intake compared to intravenous glucose delivery.
Research has established that the incretin effect is substantially diminished in certain metabolic states, making the incretin axis a critical focus of metabolic research. GIP (glucose-dependent insulinotropic polypeptide) is secreted by K-cells of the duodenum and proximal jejunum and activates the GIPR, a related class B GPCR. The interplay between GLP-1R and GIPR activation is a central theme in dual agonist research.
Research Landscape
Current laboratory research using GLP-1 agonists spans a broad range of model systems:
- Pancreatic beta cell mass and apoptosis models
- Neuronal signalling in hypothalamic appetite regulation circuits
- Hepatic lipid metabolism and steatosis models
- Cardiac and renal cell function assays
- Receptor biased agonism and internalisation kinetics
- GLP-1R/GIPR cross-talk and synergy studies
All GLP-1 receptor agonists supplied by Nova Biolabs are lyophilised compounds for in vitro laboratory research use only.
GLP-1 Compounds at Nova Biolabs
| Compound | Class | Receptor Targets | Sizes Available |
|---|---|---|---|
| Semaglutide | Peptide agonist | GLP-1R | 10mg |
| Tirzepatide | Dual agonist | GLP-1R + GIPR | 10mg, 20mg, 40mg |
| Retatrutide | Triple agonist | GLP-1R + GIPR + GCGR | 10mg, 30mg |
All products held in UK domestic stock. For laboratory research use only.