The short version of incretin fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-21 and is reviewed periodically as new material appears.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released after nutrient intake. The molecule contains 31 amino acid residues and differs from the native sequence at several positions. A non-natural residue at position eight resists the enzyme that normally truncates the hormone, while a lysine-linked fatty diacid side chain promotes binding to serum albumin. These two modifications extend the circulating half-life from minutes to roughly one week. The peptide is produced by solid-phase synthesis followed by selective acylation, and its identity and purity are confirmed by spectrometric and chromatographic techniques.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
Pharmacological activity arises from agonism at the glucagon-like peptide-1 receptor, a G protein-coupled receptor expressed in the pancreas, the gastrointestinal tract, and the brainstem. Receptor activation raises intracellular cyclic adenosine monophosphate and enhances insulin release in a glucose-dependent manner, an effect that diminishes when blood glucose concentration is low. Other effects include slowed gastric emptying and hypothalamic satiety signalling. These pathways are described well. Receptor desensitisation rates across tissues, relative to the endogenous hormone, are still under investigation, and reported findings differ between laboratories.
The company that developed the compound filed it as a long-acting analogue, and it gained first approval in 2017 for type 2 diabetes. Later authorisations from several regulators extended the indication to chronic weight management, and the World Health Organization added the glucagon-like peptide-1 receptor agonist drug class to its model list of essential medicines in 2023. Production uses solid-phase peptide synthesis followed by side-chain conjugation and chromatographic purification. Supply constraints and cost differences across regions are well documented. Literature on long-term outcomes continues to grow, with many trials reporting surrogate endpoints rather than hard clinical endpoints.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Acylated GLP-1 receptor agonist | 31-residue synthetic peptide |
| Molecular formula | C187H291N45O59 | established for the free peptide |
| Appearance | White to off-white powder | as supplied before formulation |
| Solubility | Freely soluble in water | aqueous buffers near neutral pH |
| Typical storage | 2 to 8 degrees Celsius, protected from light | powder and solution forms differ in shelf life |
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
Two structural features account for the prolonged half-life of semaglutide. A modified amino acid at position 8 resists cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1. A fatty diacid side chain binds serum albumin, which limits renal clearance and protects the peptide from enzymatic breakdown. These modifications yield a plasma half-life of approximately one week in humans, allowing once-weekly administration. The relationship between plasma concentration and clinical effect varies between individuals, and sources of that variability are still being characterized.
is dimensionless since activity is dimensionless. Activities of the products of dissociation are placed in the numerator, activities of the reactants are placed in the denominator. See activity coefficient for a derivation of this expression.
While the 30-day stunt was not an officially endorsed marketing campaign by Taco Bell, then CEO Mark King later invited Reid to Taco Bell's headquarters in Irvine, California. Reid was also a guest on an official Taco Bell podcast in 2023, discussing the stunt and its effect on his physical health. In 2023, the company test-marketed a vegan Crunchwrap Supreme in Los Angeles, New York, and Orlando to gauge the potential of a national roll out. Bon Appétit tested a vegan Crunchwrap alongside a non-vegan Crunchwrap purchased at the store in midtown Manhattan and said "the differences between the two were also genuinely difficult to discern." On August 29, 2025, the company announced that it would be abrogating its artificial intelligence-powered drive-thrus due to technical difficulties and "trolling," including one instance where a customer ordered 18,000 waters. According to reports, the AI would erroneously tell customers that the store was out of all ingredients except for soda and sauce packets. There were also reports of the AI bots simply disallowing customers to modify their orders, such as replacing meat with beans. The phenomenon quickly became an internet meme. One video on TikTok appeared to show a customer attempting to order McDonald's food items from Taco Bell, which was allowed by the system. Dane Mathews, the chain's Chief Digital and Technology Officer, told the Wall Street Journal: "We’re learning a lot, I’m going to be honest with you. [...] I can tell you it's a very active conversation inside Taco Bell in partnership with our franchisees.
=== Material Science Applications === Organic Electronics Polymeric Materials Consumer Packaged Goods Catalysis & Reactivity Thin Film Processing Energy Capture & Storage Pharmaceutical Formulations & Delivery Metals, Alloys & Ceramics In addition to computational platforms, Schrödinger develops custom software for enterprises, as well as training, computer-cluster design and implementation, and research-based drug discovery projects. Schrödinger software licenses are available to academic institutions for education and not-for-profit research.
== Cannabinoids == Cannabinoids are the compounds found in cannabis, which is a euphoriant and hallucinogenic drug prepared from the dried leaves of the strong-smelling plant Cannabis sativa. It includes synthetic cannabinoids (spice, K2), and tetrahydrocannabinol (THC, Delta-8).
Sources: en.wikipedia.org
Drosophila melanogaster can be distinguished from related species by the following combination of features: gena ~1/10 diameter of eye at greatest vertical height; wing hyaline and with costal index 2.4; male protarsus with a single row of ~12 setae forming a sex comb; male epandrial posterior lobe small and nearly triangular; female abdominal tergite 6 with dark band running to its ventral margin; female oviscapt small, pale, without dorsodistal depression and with 12–13 peg-like outer ovisensilla.
== Function in protein termination == Protein elongation continues until a stop codon appears on the mRNA. A Class I release factor (RF1 or RF2) binds to the stop codon, which induces hydrolysis of the tRNA-peptide bond in the P site, allowing the newly-formed protein to exit the ribosome. The nascent peptide continues to fold and leaves the 70S ribosome, the mRNA, the deacylated tRNA (P site), and the Class I release factor (A site). In a GTP-dependent manner, the subsequent recycling is catalyzed by a Class II release factor named RF3/prfC, Ribosome recycling factor (RRF), Initiation Factor 3 (IF3) and EF-G. The protein RF3 releases the Class I release factor so that it may occupy the ribosomal A site. EF-G hydrolyzes GTP and undergoes a large conformational change to push RF3 down the ribosome, which occurs alongside tRNA dissociation and promotes the ribosomal subunit rotation. This motion actively splits the B2a/B2b bridge, which connects the 30S and the 50S subunits, so that the ribosome can split. IF3 then isolates the 30S subunit to prevent re-association of the large and small subunits.
=== Medical and diagnostic applications === Prospective parents can be tested for being genetic carriers, or their children might be tested for actually being affected by a disease. DNA samples for prenatal testing can be obtained by amniocentesis, chorionic villus sampling, or even by the analysis of rare fetal cells circulating in the mother's bloodstream. PCR analysis is also essential to preimplantation genetic diagnosis, where individual cells of a developing embryo are tested for mutations.
Sources: en.wikipedia.org
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and neutral endopeptidases. Semaglutide carries a non-natural amino acid at position eight that blocks that cleavage, and a fatty diacid side chain that binds albumin. The result is a much longer duration of action than the native hormone.
The fatty diacid chain associates strongly with serum albumin, which keeps the peptide in circulation and shields it from rapid renal clearance. Bound peptide is released gradually, producing a sustained receptor signal. This mechanism also reduces the peak-to-trough variation seen with shorter-acting analogues.
The balance between peripheral receptor activation and signalling in the central nervous system is not fully resolved. The extent to which slowed gastric emptying accounts for reduced energy intake, compared with direct effects on appetite circuits, is debated. Long-term effects on lean mass and on tissues outside the gut and brain are still under study.
It is a glucagon-like peptide-1 receptor agonist, often grouped with the incretin mimetics. Its backbone is modified from the human hormone to resist enzymatic degradation and to bind albumin. These two features distinguish it from the native peptide.