The short version of receptor agonist fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-13. Anything still debated is marked as such rather than presented as settled.
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 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 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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
Serum protein binding dominates the pharmacokinetic profile. The attached chain associates strongly with albumin, shielding the peptide from enzymatic attack and slowing filtration by the kidney. This interaction extends the circulation half-life to roughly one week in humans, which supports weekly administration intervals. An oral version pairs the peptide with an absorption enhancer that transiently alters gastric epithelium, permitting limited uptake; bioavailability by that route is substantially lower than by injection.
Semaglutide belongs to the glucagon-like peptide-1 receptor agonist class, a group of synthetic peptides that imitate an incretin hormone released by intestinal L cells after food intake. Native GLP-1 circulates for only a few minutes because dipeptidyl peptidase-4 cleaves it rapidly. The hormone acts on pancreatic islets, the gastrointestinal tract, and several brain regions. Because the natural peptide is short-lived, development work concentrated on analogues that keep receptor activity while resisting enzymatic breakdown and renal clearance.
Activation of the GLP-1 receptor couples to Gs signalling and raises intracellular cyclic AMP in pancreatic beta cells. The resulting insulin release depends on prevailing glucose concentrations, so the effect is greater when glucose is elevated. Receptor engagement also suppresses glucagon secretion and slows gastric emptying, which flattens post-meal glucose excursions. In the central nervous system, signalling in hypothalamic and brainstem regions is associated with reduced appetite and lower energy intake. Studies continue to examine effects on cardiac, renal and hepatic endpoints; whether those benefits are independent of weight change remains an open question.
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
Pathology Laboratory Clinical Biology Laboratory Virology Laboratory Parasitology Laboratory Clinical Microbiology Laboratory Immunology Unit Data Center Administration The INRB is based at Avenue de la Démocratie (formerly Avenue des Huileries), BP 1197, Kinshasa-Gombe, DRC.
=== Philanthropy === In 1998, DiCaprio and his mother donated $35,000 for a "Leonardo DiCaprio Computer Center" at a library in Los Feliz. In May 2009, DiCaprio joined Kate Winslet, director James Cameron and Canadian singer Celine Dion, in a campaign to raise money to financially support the fees of the nursing home where Millvina Dean, a survivor of the RMS Titanic, was residing. DiCaprio and Winslet donated $20,000 to support Dean. In 2010, he donated $1 million to relief efforts in Haiti after the earthquake. In 2011, DiCaprio joined the Animal Legal Defense Fund's campaign to release Tony, a tiger that had spent the last decade at a truck stop in Grosse Tête, Louisiana. DiCaprio donated $61,000 to the gay rights group GLAAD in 2013. In 2016, DiCaprio donated $65,000 to the annual fundraising gala for the Children of Armenia Fund, where he was a special guest of his friend and honorary chair, Tony Shafrazi. Supporting Hurricane Harvey (2017) relief efforts, DiCaprio provided $1 million through his foundation. In 2020, DiCaprio's foundation donated $3 million to Australia bushfire relief efforts. Amidst the 2022 Russian invasion of Ukraine, the media announced DiCaprio donated $10 million to support Ukraine, although the news agency Associated Press suggested this amount was inaccurate.
== Signs and symptoms == In one of the few reported cases, the subject presented with muscle weakness and fatigue, muscle twitching, excessive sweating and salivation, small joint pain, itching and weight loss. The subject also developed confusional episodes with spatial and temporal disorientation, visual and auditory hallucinations, complex behavior during sleep and progressive nocturnal insomnia associated with diurnal drowsiness. There was also severe constipation, urinary incontinence, and excessive lacrimation. When left alone, the subject would slowly lapse into a stuporous state with dreamlike episodes characterized by complex and quasi-purposeful gestures and movements (enacted dreams). Marked hyperhidrosis and excessive salivation were evident. Neurological examination disclosed diffuse muscle twitching and spontaneous and reflex myoclonus, slight muscle atrophy in the limbs, absence of tendon reflexes in the lower limbs and diffuse erythema especially on the trunk with scratching lesions of the skin. Compulsive behaviours, stereotypies and reduplicative paramnesias can be part of the CNS spectrum.
It is used as a reagent in the Bouveault aldehyde synthesis and in the Vilsmeier-Haack reaction, another useful method of forming aldehydes. It is a common solvent in the Heck reaction. It is a common catalyst used in the synthesis of acyl halides, in particular the synthesis of acyl chlorides from carboxylic acids using oxalyl or thionyl chloride. The catalytic mechanism entails reversible formation of an imidoyl chloride (also known as the 'Vilsmeier reagent'):
Sources: en.wikipedia.org
== Epidemiology == According to a Japanese study from 2007, Bethlem myopathy 1 affects about 1 in 200,000 people. A 2009 study, concerning the prevalence of genetic muscle disease in Northern England, estimated the prevalence of Bethlem myopathy 1 to be at 0.77:100,000. Together with Ullrich congenital muscular dystrophy 1, Bethlem myopathy 1 is believed to be underdiagnosed. Both conditions have been described in individuals from a variety of ethnic backgrounds. Bethlem myopathy 2 affects less than 1 in 1,000,000 people.
==== Medications ==== Nonsteroidal anti-inflammatory drugs (NSAIDs) may help if the pain is caused by inflammation. However, long-term use of NSAIDs is often a risk factor for gastrointestinal, renal, and blood-related side effects. It can worsen symptoms of mast cell activation syndrome, a disease that may be associated with EDS. Acetaminophen can be used to avoid the bleeding-related side effects of NSAIDs. Lidocaine can be applied topically after subluxations and painful gums. It can also be injected into painful areas in the case of musculoskeletal pain. If the pain is neuropathic in origin, tricyclic antidepressants in low doses, anticonvulsants, and selective norepinephrine reuptake inhibitors can be used.
== Video game == To coincide with the film's release, Sony Pictures commissioned video game developer Black Widow Games to develop a promotional tie-in mod for the video game Half-Life titled Underworld: Bloodline. The mod was available on Sony Pictures' official website until the end of 2007. An asymmetric multiplayer FPS, the game tasks players with choosing between Vampires and Lycans, engaging in objective-based combat across urban maps. Each faction features distinct classes, weapons, and movement abilities, while gameplay revolves around capturing or defending Hybrid NPCs across four maps, blending mechanics inspired by Half-Life's mods Counter-Strike and Vampire Slayer. It is the only officially licensed Half-Life mod tied to a Hollywood movie.
Sources: en.wikipedia.org
==== Solid samples ==== Solid samples can be prepared in a variety of ways. One common method is to crush the sample with an oily mulling agent (usually mineral oil Nujol). A thin film of the mull is applied onto salt plates and measured. The second method is to grind a quantity of the sample with a specially purified salt (usually potassium bromide) finely (to remove scattering effects from large crystals). This powder mixture is then pressed in a mechanical press to form a translucent pellet through which the beam of the spectrometer can pass. A third technique is the "cast film" technique, which is used mainly for polymeric materials. The sample is first dissolved in a suitable, non-hygroscopic solvent. A drop of this solution is deposited on the surface of a KBr or NaCl cell. The solution is then evaporated to dryness and the film formed on the cell is analysed directly. Care is important to ensure that the film is not too thick otherwise light cannot pass through. This technique is suitable for qualitative analysis. The final method is to use microtomy to cut a thin (20–100 μm) film from a solid sample. This is one of the most important ways of analysing failed plastic products for example because the integrity of the solid is preserved. In photoacoustic spectroscopy the need for sample treatment is minimal. The sample, liquid or solid, is placed into the sample cup which is inserted into the photoacoustic cell which is then sealed for the measurement. The sample may be one solid piece, powder or basically in any form for the measurement.
For promotion from the Secondary level (Class IX-X) to the Senior Secondary level (Class XI-XII), a student must obtain, for all subjects (or best five if six subjects are taken), 33% overall, without any minimum theory mark requirement. Initially, the passing criteria were set such that a student had to get 33% in both the theory and practical components. However, an exemption was initially granted to students who wrote the exam in 2018, as they had gone through the old CCE system the previous year. However, CBSE later extended this relief for students writing the exam from 2019 and later as well. Students who do not manage to pass up to two subjects can write the compartment in those subjects in July. Those who fail a compartment or three or more subjects must retake all subjects taken the following year.
Glutathione, along with oxidized glutathione (GSSG) and S-nitrosoglutathione (GSNO), have been found to bind to the glutamate recognition site of the NMDA and AMPA receptors (via their γ-glutamyl moieties), and may be endogenous neuromodulators. At millimolar concentrations, they may also modulate the redox state of the NMDA receptor complex. In addition, glutathione has been found to bind to and activate ionotropic receptors that are different from any other excitatory amino acid receptor, and which may constitute glutathione receptors, potentially making it a neurotransmitter. As such, since N-acetylcysteine is a prodrug of glutathione, it may modulate all of the aforementioned receptors as well. Glutathione also modulates the NMDA receptor by acting at the redox site. Acetylcysteine also is a precursor to cystine, which in turn is a substrate for the cystine-glutamate antiporter on astrocytes; hence there is increasing glutamate release into the extracellular space. This glutamate in turn acts on mGluR2/3 receptors, and at higher doses of acetylcysteine, mGluR5. Acetylcysteine may have other biological functions in the brain, such as the modulation of dopamine release and the reduction in inflammatory cytokine formation possibly via inhibiting NF-κB and modulating cytokine synthesis.
=== Subtilisin-like === Subtilisin is a serine protease in prokaryotes. Subtilisin is evolutionarily unrelated to the chymotrypsin-clan, but shares the same catalytic mechanism utilising a catalytic triad, to create a nucleophilic serine. This is the classic example used to illustrate convergent evolution, since the same mechanism evolved twice independently during evolution.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and cleared quickly. Semaglutide carries a position 8 substitution that blocks that cleavage and a fatty diacid chain that binds albumin. Together these changes extend its circulating half-life to about one week.