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.
This page was last updated on 2025-10-23 and is reviewed periodically as new material appears.
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.
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 | Parent peptide; salt forms also reported |
| Molecular mass | about 4113.6 Da | Average mass of the free peptide |
| Peptide length | 31 amino acids | Backbone related to GLP-1(7-37) |
| Key substitution | Aib at position 8 | Blocks DPP-4 cleavage |
| Albumin binding | Via C-18 diacid side chain | Prolongs circulation time |
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.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
The sequence incorporates alpha-aminoisobutyric acid at position 8, replacing the alanine found in the natural hormone. This substitution blocks the primary DPP-4 recognition site and contributes most of the enzymatic stability. Albumin binding further protects the peptide and reduces the frequency of administration required to maintain active plasma levels. Because the fatty acid chain increases lipophilicity, the compound is formulated as a solution rather than a simple aqueous buffer. Researchers describe the design as an incremental optimization of earlier GLP-1 analogs rather than a wholly new scaffold.
Reported molecular weight is approximately 4113.6 daltons for the free base, and the peptide is supplied as a lyophilized powder or in buffered liquid form depending on the intended use. It is freely soluble in water when formulated with appropriate excipients, though the unconjugated peptide shows limited stability at neutral pH over long periods. Analytical characterization typically relies on reversed-phase high-performance liquid chromatography and mass spectrometry. Purity specifications for research-grade material commonly exceed ninety-five percent by area. Isotopic and impurity profiles differ between suppliers.
Lyophilized semaglutide powder is typically held at minus twenty degrees Celsius for long-term storage. At that temperature, solid-state degradation reactions proceed slowly and the peptide remains intact for extended periods. Repeated freeze-thaw cycles are best avoided because they promote aggregation and can shift the proportion of monomeric peptide present. Working aliquots are often prepared so that each portion is thawed only once, and desiccant is placed inside the vial to limit moisture uptake.
Identity and purity are usually assessed by reverse-phase high-performance liquid chromatography coupled to mass spectrometry. Retention time and observed mass are compared against a reference standard run under identical conditions. Impurity profiles reveal deamidation products, oxidized methionine variants, and truncated fragments that arise during synthesis or storage. Peptide mapping through enzymatic digestion confirms the primary sequence, while amino acid analysis offers an independent check on overall composition.
Stability studies examine how temperature, pH, and moisture influence degradation rates over time. In aqueous solution, hydrolysis and deamidation accelerate as pH moves away from mildly acidic conditions. Light exposure and residual metal ions can also trigger oxidation of susceptible residues. Accelerated aging at elevated temperature is used to estimate shelf life, though extrapolation to room temperature carries uncertainty because individual degradation pathways do not always scale predictably.
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。
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
Building automation, access control, smart energy — DASH7's signal propagation characteristics allow it to penetrate walls, windows, doors, and other substances that serve as impediments to other technologies operating at 2.45 GHz, for example. For smart energy and building automation applications, DASH7 networks can be deployed with far less infrastructure than competing technologies and at far lower total cost of ownership. Location-based services — DASH7 is being used today for developing new location-based services using a range of DASH7-enabled devices, including smartcards, keyfobs, tickets, watches and other conventional products that can take advantage of the unique small footprint, low power, long range, and low cost of DASH7 relative to less practical and high-power wireless technologies like Wi-Fi or Bluetooth. Using DASH7, users can "check in" to venues in ways not practical with current check-in technologies like GPS, that are power-intensive and fail indoors and in urban environments. Location-based services like Foursquare, Novitaz, or Facebook can exploit this capability in DASH7 and award loyalty points, allow users to view the Facebook or X, formally known as Twitter, addresses of those walking past, and more. Mobile advertising — DASH7 is being developed for "smart" billboards and kiosks, likewise "smart" posters that can be read from many meters (or even kilometers) away, creating new opportunities for both tracking the effectiveness of advertising expenditures, but also creating new e-commerce opportunities.
Historically, the birth rate of teenagers peaked in the late 1950s and early 1960s. However, at that time, most teenage parents were married. In the early twenty-first century, nine in ten births to the age group 15-19 are to unmarried mothers. Social norms have changed; it is now not unusual for teenagers to delay or avoid sexual intercourse altogether. Younger teenagers are more likely to practice abstinence than their older counterparts. A report published by the Center for Disease Control and Prevention (CDC) in early 2018 found the number of high school students who have had sex fell from 47% in 2005 down to 41% in 2015, with the most dramatic drop taking place between 2013 and 2015. On top of that, among never-married teens who have had sex, overwhelming majorities reported they used contraception the first time they did it. There are a few reasons for this. First, Millennials and Generation Z are more focused on the consequences of sex than their predecessors were. Second, there has been growing concern over unwanted sexual advances, especially in the wake of the Me-too movement. Writing for The Spectator, Douglas Murray dubbed this the "sexual counter-revolution." Third, as a consequence of the precarious contemporary economy, young adults today are more likely to be living with their parents rather than on their own, with a romantic partner, or a spouse. A 2016 analysis by the CDC discovered that teenage birthrates nosedived between 1991, when they reached a crisis point, and 2014, when they dropped by 60%, a record low.
== Role of the clinical data manager in a clinical trial == Job profile acceptable in CDM: clinical researcher, clinical research associate, clinical research coordinator etc. The clinical data manager plays a key role in the setup and conduct of a clinical trial. The data collected during a clinical trial form the basis of subsequent safety and efficacy analysis which in turn drive decision making on product development in the pharmaceutical industry. The clinical data manager is involved in early discussions about data collection options and then oversees development of data collection tools based on the clinical trial protocol. Once subject enrollment begins, the data manager ensures that data are collected, validated, complete, and consistent. The clinical data manager liaises with other data providers (e.g. a central laboratory processing blood samples collected) and ensures that such data are transmitted securely and are consistent with other data collected in the clinical trial. At the completion of the clinical trial, the clinical data manager ensures that all data expected to be captured have been accounted for and that all data management activities are complete. At this stage, the data are declared final (terminology varies, but common descriptions are "Database Lock", “Data Lock” and "Database Freeze"), and the clinical data manager transfers data for statistical analysis.
=== Geneva lens measure === The Geneva Lens Measure is a device used to measure curved surfaces. It is most commonly used by opticians to measure lenses but can also be used by paleontologists to estimate the life size of dinosaur eggs from shell fragments. The instrument can be used to help estimate the size of fossil eggshells by measuring their curved surfaces. Since most eggs aren't perfectly round measurements from multiple parts of the egg with varying shell curvatures may be needed to get a full idea of the egg's size. Ideally an eggshell fragment being used to estimate the full size of an egg should be more than 3 cm long. Smaller eggshell fragments are better suited to other methods of study, like the Obrig radius dial gauge. The Geneva Lens measure gives units in diopters which must be converted to the radius in millimeters. Use of the Geneva Lens Measure to estimate the size of a fossil egg was first done by Sauer on fossil ostrich eggs.
Sources: en.wikipedia.org
29 July – Laura Mackenzie, whose offer of a job with Police Scotland was withdrawn when it emerged she had been prescribed antidepressants, launches legal action against the force. The offer was withdrawn after her medical history came to light during a health examination prior to starting the job, and because Police Scotland requires any recruits to be clear of antidepressant medication for at least two years. 31 July Media outlets, including BBC News, report that a medical student has been expelled from the University of Dundee after filming the dissection of a human body and posting the footage online. The 2023 Rutherglen and Hamilton West recall petition closes. A by-election is triggered after the petition to remove Margaret Ferrier from office is signed by 11,896 of the 81,124 eligible constituents, passing the required 10% threshold.
R2NH + R'C(O)Cl + (CH3CH2)3N → R'C(O)NR2 + [(CH3CH2)3NH]+Cl− Like other tertiary amines, it catalyzes the formation of urethane foams and epoxy resins. It is also useful in dehydrohalogenation reactions and Swern oxidations. Triethylamine is readily alkylated to give the corresponding quaternary ammonium salt:
=== Methylthiolation of tRNAs === Methylthiotransferases belong to a subset of radical SAM enzymes that contain two [4Fe-4S]+ clusters and one radical SAM domain. Methylthiotransferases play a major role in catalyzing methylthiolation on tRNA nucleotides or anticodons through a redox mechanism. Thiolation modification is believed to maintain translational efficiency and fidelity. MiaB and RimO are both well-characterized and bacterial prototypes for tRNA-modifying methylthiotransferases
Sources: en.wikipedia.org
It belongs to the incretin mimetic class and acts as a long-acting glucagon-like peptide-1 receptor agonist. The class includes several peptides with different half-lives and routes of administration.
The side chain enables reversible binding to albumin in the bloodstream, which protects the peptide from rapid renal clearance. This extends the interval between administrations compared with unmodified GLP-1.
No. It shares much of the native sequence but carries substitutions and an added side chain. These changes increase stability against enzymatic breakdown.
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.