This is a working overview of GLP-1 receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-30. Anything still debated is marked as such rather than presented as settled.
Reverse-phase high-performance liquid chromatography is the standard method for purity assessment, separating the peptide from truncated or oxidized variants. Mass spectrometry confirms molecular mass and detects modifications, while ultraviolet absorbance near 280 nanometers supports concentration measurement through tryptophan and tyrosine residues. Circular dichroism can indicate secondary structure, though the peptide is largely helical in solution, and ion-exchange chromatography resolves charge variants. Purity values above 95 percent are typical for research-grade material. Stability studies track degradation over time under defined conditions.
Lyophilized semaglutide is typically stored at temperatures between minus 20 and minus 80 degrees Celsius for long-term preservation. Short-term storage at 2 to 8 degrees Celsius is common for working aliquots. Repeated freeze-thaw cycles can degrade the peptide and are usually avoided. The molecule is hygroscopic in its solid form, so containers should remain sealed with desiccant. Solutions are less stable than powders and are generally prepared fresh. Light exposure is limited because aromatic residues can undergo photo-oxidation.
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.
Semaglutide is a synthetic peptide of thirty-one amino acids that shares roughly ninety-four percent sequence identity with human glucagon-like peptide-1. Two substitutions resist enzymatic cleavage by dipeptidyl peptidase-4, and a fatty diacid side chain attached through a linker promotes binding to serum albumin. That albumin binding slows renal clearance and extends the circulating half-life from minutes to approximately one week. The structural changes are well established in the published literature. Whether the same modifications affect receptor signalling bias in ways that matter clinically remains an open 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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized form |
| Solubility | Water and aqueous buffers | Near neutral pH |
| Storage temperature | Minus 20 to minus 80 C | Long-term, lyophilized |
| Analytical method | RP-HPLC | Purity assessment |
| Typical purity | Greater than 95 percent | Research-grade material |
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物，其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代，使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸，进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链，该侧链赋予分子与血浆白蛋白结合的能力。
该分子作为 GLP-1 受体的选择性激动剂发挥作用，受体属于 B 类 G 蛋白偶联受体家族，激活后经 Gs 通路提升细胞内环腺苷酸水平。在胰腺 β 细胞，信号促进葡萄糖依赖性的胰岛素释放，血糖偏低时该作用明显减弱。在胰岛 α 细胞，胰高血糖素分泌受到抑制。中枢神经系统与胃肠道同样存在受体表达，相应信号参与食欲调节以及胃排空速率的降低。
Large randomised trials in adults with type 2 diabetes and in adults with obesity have reported reductions in body weight and improvements in several cardiovascular risk markers. One outcome trial found a lower incidence of major adverse cardiovascular events in participants with diabetes and established cardiovascular disease. Gastrointestinal effects such as nausea and vomiting are the most frequently reported adverse events and often diminish over time. Changes in lean body mass during weight loss are an area of ongoing investigation. Effects in adolescents and in pregnancy are less well characterised, and current labelling advises against use during pregnancy.
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.
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.
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.
The clearance rate, or the rate at which the carrier protein is broken down, for GHBP alone is much faster than when it is bound to its ligand. Additionally, current literature provides evidence that the carrier-protein prolongs the half-life of growth hormone through its binding with the ligand. One purpose of GHBP can be inferred: to maintain the level of GH in the blood, as roughly half of its concentration is complexed with GHBP. Yet this could be confounded by the fact that GH binding to GHBP prevents the ligand from binding to GHR and ultimately proteolytic activity. Another function is that GHBP displays competitive inhibition for GH against the GHR receptor. Studies elucidate another aspect of GHBP physiological role: The proteolytic cleavage activity that forms GHBP ultimately regulates GHR production in humans as well as rats. If there is low GHBP concentration then there are high levels of GHR expression. Conversely, high levels of GHBP protein show negative correlation with levels of growth hormone receptor expression.
A weak and emaciated Tolkien spent the remainder of the war alternating between hospitals and garrison duties, being deemed medically unfit for general service. During his recovery in a cottage in Little Haywood, Staffordshire, he began to work on what he called The Book of Lost Tales, beginning with The Fall of Gondolin. Lost Tales represented Tolkien's attempt to create a mythology for England, a project he would abandon without ever completing. Throughout 1917 and 1918 his illness kept recurring, but he had recovered enough to do home service at various camps. It was at this time that Edith bore their first child, John Francis Reuel Tolkien. In a 1941 letter, Tolkien described his son John as "(conceived and carried during the starvation-year of 1917 and the great U-boat campaign) round about the Battle of Cambrai, when the end of the war seemed as far off as it does now". Tolkien was promoted to the temporary rank of lieutenant on 6 January 1918. When he was stationed at Kingston upon Hull, he and Edith went walking in the woods at nearby Roos, and Edith began to dance for him in a clearing among the flowering hemlock. After his wife's death in 1971, Tolkien remembered:
Universities incorporated as higher education corporations are regarded as public authorities for some purposes, even if they do not receive public funding. If a university in England receives public funding, the government regulates the tuition fees the university can charge. In addition, registration as a higher education provider is obligatory for English universities, whether or not they are publicly funded, and requires adherence to public interest governance principles. All registered providers in England must also be members of the Office of the Independent Adjudicator. However, direct government funding for universities has declined since 2012. Between 2014 and 2018, funding council grants dropped from 18% to 15% for University College London (a large research university), 17% to 11% for Durham University (a small research university), and 15% to 8% for the University of Hertfordshire (a teaching-focused university). Each of the four nations within the United Kingdom is responsible for higher education as a devolved matter and have adopted different methods of support for resident students. Scotland offers free tuition for residents for their first undergraduate degree in Scotland. The Welsh Government provides means-tests grants and loans to students, based on family income; the funding follows Welsh students, even if they choose to study outside of Wales. England and Northern Ireland expect students to take out student loans to cover the cost of tuition.
== Function == Cytosolic and membrane-bound forms of glutathione S-transferase are encoded by two distinct supergene families. At present, eight distinct classes of the soluble cytoplasmic mammalian glutathione S-transferases have been identified: alpha, kappa, mu, omega, pi, sigma, theta, and zeta. This gene encodes a glutathione S-transferase that belongs to the mu class. The mu class of enzymes functions in the detoxification of electrophilic compounds, including some carcinogens, therapeutic drugs, environmental toxins and products of oxidative stress, by conjugation with glutathione. The genes encoding the mu class of enzymes are organized in a gene cluster on chromosome 1p13.3 and are known to be highly polymorphic. These genetic variations can change an individual's susceptibility to carcinogens and toxins as well as affect the toxicity and efficacy of certain drugs. Mutations of this class mu gene have been linked with a slight increase in a number of cancers, likely due to exposure with environmental toxins.
The most complex RPR synthesized by that point was called 24-3, which was newly capable of polymerizing the sequences of a substantial variety of nucleotide sequences and navigating through complex secondary structures of RNA substrates inaccessible to previous ribozymes. In fact, this experiment was the first to use a ribozyme to synthesize a tRNA molecule. Starting with the 24-3 ribozyme, Tjhung et al. applied another fourteen rounds of selection to obtain an RNA polymerase ribozyme by in vitro evolution termed '38-6' that has an unprecedented level of activity in copying complex RNA molecules. However, this ribozyme is unable to copy itself and its RNA products have a high mutation rate. In a subsequent study, the researchers began with the 38-6 ribozyme and applied another 14 rounds of selection to generate the '52-2' ribozyme, which compared to 38-6, was again many times more active and could begin generating detectable and functional levels of the class I ligase, although it was still limited in its fidelity and functionality in comparison to copying of the same template by proteins such as the T7 RNA polymerase. An RPR called t5(+1) adds triplet nucleotides at a time instead of just one nucleotide at a time. This heterodimeric RPR can navigate secondary structures inaccessible to 24-3, including hairpins. In the initial pool of RNA variants derived only from a previously synthesized RPR known as the Z RPR, two sequences separately emerged and evolved to be mutualistically dependent on each other.
Sources: en.wikipedia.org
==== South Asia ==== Slavery in India was widespread by the 6th century BC, and perhaps even as far back as the Vedic period. Slavery intensified during the Muslim domination of northern India after the 11th century. Slavery existed in Portuguese India after the 16th century. The Dutch, too, largely dealt in Abyssian slaves, known in India as Habshis or Sheedes. Arakan/Bengal, Malabar, and Coromandel remained the largest sources of forced labour until the 1660s. Between 1626 and 1662, the Dutch exported on an average 150–400 slaves annually from the Arakan-Bengal coast. During the first 30 years of Batavia's existence, Indian and Arakanese slaves provided the main labour force of the Dutch East India Company, Asian headquarters. An increase in Coromandel slaves occurred during a famine following the revolt of the Nayaka Indian rulers of South India (Tanjavur, Senji, and Madurai) against Bijapur overlordship (1645) and the subsequent devastation of the Tanjavur countryside by the Bijapur army. Reportedly, more than 150,000 people were taken by the invading Deccani Muslim armies to Bijapur and Golconda. In 1646, 2,118 slaves were exported to Batavia, the overwhelming majority from southern Coromandel. Some slaves were also acquired further south at Tondi, Adirampatnam, and Kayalpatnam. Another increase in slaving took place between 1659 and 1661 from Tanjavur as a result of a series of successive Bijapuri raids.
== Career == Flay dropped out of high school at age 17. He said that his first jobs in the restaurant industry were at a pizza parlor and Baskin-Robbins. He then took a position making salads at Joe Allen Restaurant in Manhattan's Theater District, where his father was a partner. The owner, Joe Allen, was impressed by Flay's natural ability and agreed to pay his partner's son's tuition at the French Culinary Institute. Flay received a degree in culinary arts and was a member of the first graduating class of the French Culinary Institute in 1984. After culinary school, he started working as a sous-chef, quickly learning the culinary arts. At the Brighton Grill on Third Avenue, Flay was handed the executive chef position a week after the executive chef was fired. Flay quit when he realized he was not ready to run a kitchen. He took a position as a chef working for restaurateur Jonathan Waxman at Bud and Jams. Waxman introduced Flay to southwestern, which came to define his culinary career. After working for a short time on the floor at the American Stock Exchange, Flay returned to the kitchen as the executive chef of Miracle Grill in the East Village, where he worked from 1988 to 1990. He caught the attention of Jerome Kretchmer, who was looking for a southwestern-style chef. Impressed by Flay's food, Kretchmer offered him the position of executive chef of Mesa Grill, which opened on January 15, 1991. Shortly after, he became a partner.
The human and animal data consistently indicate a lack of carcinogenicity via the oral route of exposure and limit the carcinogenicity of nickel compounds to respiratory tumours after inhalation. Nickel metal is classified as a suspect carcinogen; there is consistency between the absence of increased respiratory cancer risks in workers predominantly exposed to metallic nickel and the lack of respiratory tumours in a rat lifetime inhalation carcinogenicity study with nickel metal powder. In the rodent inhalation studies with various nickel compounds and nickel metal, increased lung inflammations with and without bronchial lymph node hyperplasia or fibrosis were observed. In rat studies, oral ingestion of water-soluble nickel salts can trigger perinatal mortality in pregnant animals. Whether these effects are relevant to humans is unclear as epidemiological studies of highly exposed female workers have not shown adverse developmental toxicity effects. People can be exposed to nickel in the workplace by inhalation, ingestion, and contact with skin or eye. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for the workplace at 1 mg/m3 per 8-hour workday, excluding nickel carbonyl. The National Institute for Occupational Safety and Health (NIOSH) sets the recommended exposure limit (REL) at 0.015 mg/m3 per 8-hour workday. At 10 mg/m3, nickel is immediately dangerous to life and health. Nickel carbonyl [Ni(CO)4] is an extremely toxic gas.
=== July to December 2003 === American forces detained the family of an unidentified lieutenant general to induce him to turn himself in. The abuses at Abu Ghraib prison were reportedly committed by MPs. There are allegations that private contractors contributed to them as well and that intelligence agencies such as the CIA ordered them to do so in order to break prisoners for interrogations. It is said to be a usual practice in other US prisons as well, such as in Afghanistan and Guantanamo Bay. The International Committee of the Red Cross submitted a detailed report to the U.S. Army in October 2003 about abuses in prisons, and the president of the Red Cross stated he had informed high-ranking members of the Bush administration about the abuses during a meeting in the White House in January 2004. A soldier came forward that month with photos of abuse that he found disturbing, some showed the stacking of prisoners into a human pyramid, with one prisoner's skin visibly bearing a slur written in English. Another showed a prisoner being forced to stand on a box with wires attached to his head and hands, who had reportedly been told that if he fell off the box, he would be electrocuted. Photos released to the public later included a person being attacked by a guard dog, which the soldier involved described as being useful for intimidation of prisoners. It was also reported that an Iraqi hired as a translator raped a juvenile male prisoner while a female soldier took pictures.
=== Functions of macrophytes in aquatic systems === Macrophytes perform many ecosystem functions in aquatic ecosystems and provide services to human society. One of the important functions performed by macrophyte is uptake of dissolved nutrients including nitrogen and phosphorus. Macrophytes are widely used in constructed wetlands around the world to remove excess N and P from polluted water. Besides direct nutrient uptake, macrophytes indirectly influence nutrient cycling; especially N cycling through influencing the denitrifying bacterial functional groups that are inhabiting on roots and shoots of macrophytes. Macrophytes promote the sedimentation of suspended solids by reducing the current velocities, impede erosion by stabilising soil surfaces. Macrophytes also provide spatial heterogeneity in otherwise unstructured water column. Habitat complexity provided by macrophytes tends to increase diversity and density of both fish and invertebrates. The additional site-specific macrophytes' value provides wildlife habitat and makes treatment systems of wastewater aesthetically satisfactory.
Sources: en.wikipedia.org
Long-term storage is usually at minus 20 to minus 80 degrees Celsius in a sealed, desiccated container. Working aliquots can be held briefly at 2 to 8 degrees Celsius.
Repeated temperature cycling can promote aggregation and peptide degradation. Dividing material into single-use aliquots limits this risk.
Mass spectrometry is commonly used to confirm molecular mass and detect structural modifications. It is often paired with chromatographic purity assessment.
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.