A practical reference on IGF-1: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-02-12 and is reviewed periodically as new material appears.
Receptor level activity follows the canonical GHRH pathway. The peptide binds the GHRH receptor, a class B G protein coupled receptor on somatotroph cells of the anterior pituitary. Binding raises intracellular cyclic AMP, which promotes calcium entry and the release of growth hormone into the bloodstream. Because the molecule acts at the same receptor as the endogenous hormone, its effect is superimposed on the natural pulsatile rhythm rather than replacing it. Whether sustained receptor occupation leads to desensitization is not fully settled.
CJC-1295 belongs to a class of synthetic peptides modeled on growth hormone releasing hormone, a forty-four amino acid signal produced by the hypothalamus. The compound is built from the first twenty-nine residues of the natural sequence, with four substitutions introduced at positions 2, 8, 15 and 27. These changes were designed to slow enzymatic breakdown while preserving receptor activation. The result is a peptide that is shorter than native GHRH and considerably more resistant to ordinary clearance pathways in circulation.
Reports on this compound commonly follow serum growth hormone and insulin-like growth factor 1 across defined time windows. Protocols differ in sampling frequency, assay platform, and participant characteristics, which makes direct comparison between publications difficult. Some work focuses on pulsatile release patterns instead of average concentrations. Whether repeated exposure alters endogenous hormone rhythms over long periods remains an open question, and the formal literature is thinner than the volume of informal commentary implies.
Once in circulation, the peptide binds the growth hormone-releasing hormone receptor displayed on pituitary somatotroph cells. Receptor activation couples to Gs proteins, elevates intracellular cyclic AMP, and drives protein kinase A signaling inside the cell. That cascade increases discharge of growth hormone into the bloodstream. The analog therefore operates through a receptor pathway that already exists for the body's own releasing hormone, rather than through an engineered artificial target.
Clearance profiles diverge sharply between the two versions. The albumin-binding molecule stays in plasma for several days, whereas the unmodified analog is largely gone within about half an hour in reported work. Cleavage by dipeptidyl peptidase IV is a major contributor to the short life of the unmodified sequence. These gaps mean the two versions cannot be substituted for each other in study design or in reading results side by side.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic GHRH analogue | Built on a 29 residue sequence |
| Primary target | GHRH receptor (GHRHR) | Class B G protein coupled receptor |
| Unconjugated half life | Minutes | Limited by protease degradation |
| Key modification | Four residue substitutions | Positions 2, 8, 15 and 27 |
| Common synonym | Modified GRF(1-29) | Usually denotes the form without DAC |
The albumin-binding version stays in circulation for days, because covalent attachment to serum albumin shields the peptide from rapid filtration and degradation. Reported half-lives for this form fall in the range of several days. The version without the linker is cleared in minutes, with estimates often near thirty minutes in animal work. These figures come from small studies and vary with assay method, species, and route, so they are best read as approximate rather than fixed constants.
Studies in this area generally track growth hormone pulses, insulin-like growth factor 1 concentrations, and occasionally body composition endpoints. Most published human data come from early, small trials, and questions about long-term effects remain open. Whether repeated exposure alters pituitary responsiveness over time is not settled. Analytical work relies on immunoassays for the hormones and on mass spectrometry for the peptide itself, because the two measurements answer different questions.
Binding of the peptide to the growth hormone-releasing hormone receptor on pituitary somatotrophs triggers a G protein coupled cascade that raises cyclic AMP and opens calcium channels. The result is greater secretion of growth hormone into the bloodstream. Because the peptide acts at the same receptor as the natural hypothalamic hormone, its effect is amplified pulse size rather than an entirely separate release pathway. Receptor binding alone does not determine the response, since somatostatin tone and other inputs modulate the final output.
Two forms circulate under the CJC-1295 name, and they differ by a single appended group. The version without a drug affinity complex carries four substitutions along the peptide chain, including a D-alanine near the amino terminus and replacements at three other positions. These changes block the enzyme dipeptidyl peptidase IV and remove a methionine residue that is prone to oxidation. The modified fragment is frequently labeled MOD GRF 1-29. Naming conventions are inconsistent across informal sources, which is a common source of confusion.
The second form adds a maleimide-bearing linker to the lysine at the carboxyl end. This group reacts with cysteine-34 on circulating serum albumin, forming a covalent bond that keeps the peptide in the bloodstream for far longer. ConjuChem developed the molecule as a way to extend the action of a peptide without frequent administration. The albumin attachment is the defining structural feature of the drug affinity complex version. Whether continuous exposure produces effects distinct from shorter pulses remains an unresolved research question.
The peptide backbone includes a D-alanine at position two, which resists cleavage by dipeptidyl peptidase IV, and several other substitutions that reduce degradation. Its molecular weight is roughly 3.4 kDa without the linker and about 3.6 kDa with it. The molecule is water soluble and is normally supplied as a lyophilized powder. Precise sequence and mass values depend on which variant is described, so technical documents usually state the exact form being referenced.
CJC-1295 is a synthetic peptide designed as a long-acting analogue of growth hormone-releasing hormone (GHRH). Its structure derives from the first 29 amino acids of native GHRH, a fragment often called GRF(1-29). Four substitutions were introduced to slow enzymatic breakdown and extend activity relative to the natural sequence. The compound was developed by ConjuChem as part of a broader effort to improve the pharmacokinetic profile of peptide hormones. It is studied in laboratory and clinical research settings rather than appearing as a naturally occurring substance.
==== Neutron activation of 98Mo ==== Production of 99Mo by neutron activation of natural molybdenum, or molybdenum enriched in 98Mo, is another, smaller, route of production. This was the original method, and gives a radio-pure product, but the large amount of remaining stable molybdenum complicates generator design.
The glucagon-like peptide-1 receptor (GLP1R) is a G protein-coupled receptor (GPCR) found on beta cells of the pancreas and on neurons of the brain. It is involved in the control of blood sugar level by enhancing insulin secretion. In humans it is synthesised by the gene GLP1R, which is present on chromosome 6. It is a member of the glucagon receptor family of GPCRs. GLP1R is composed of two domains, one extracellular (ECD) that binds the C-terminal helix of GLP-1, and one transmembrane domain (TMD) that binds the N-terminal region of GLP-1. In the TMD domain a fulcrum of polar residues regulates the biased signaling of the receptor while the transmembrane helical boundaries and extracellular surface are a trigger for biased agonism.
== Biological significance == In general, most biochemical reactions are stereoselective, so only one stereoisomer will produce the intended product while the other simply does not participate or can cause side-effects. Of note, the L form of amino acids and the D form of sugars (primarily glucose) are usually the biologically reactive form. This is due to the fact that many biological molecules are chiral and thus the reactions between specific enantiomers produce pure stereoisomers. Also notable is the fact that all amino acid residues exist in the L form. However, bacteria produce D-amino acid residues that polymerize into short polypeptides which can be found in bacterial cell walls. These polypeptides are less digestible by peptidases and are synthesized by bacterial enzymes instead of mRNA translation which would normally produce L-amino acids. The stereoselective nature of most biochemical reactions meant that different enantiomers of a chemical may have different properties and effects on a person. Many psychotropic drugs show differing activity or efficacy between isomers, e.g. amphetamine is often dispensed as racemic salts while the more active dextroamphetamine is reserved for refractory cases or more severe indications; another example is methadone, of which one isomer has activity as an opioid agonist and the other as an NMDA antagonist. Racemization of pharmaceutical drugs can occur in vivo.
The Communists contacted Kimon Georgiev through Racho Angelov, which resulted in the circles around Zveno joining the Fatherland Front. Initially, its activity consisted mainly in maintaining contacts between the activists of the different organizations and issuing common documents, and dozens of committees were established throughout the country. On 10 August 1943, a National Committee of the OF was established, including Kiril Dramaliev, Nikola Petkov, Kimon Georgiev, Grigor Cheshmedzhev and Dimo Kazasov. After the death of Tsar Boris III on 28 August 1943, Kimon Georgiev was among the opposition politicians with whom Prime Minister Bogdan Filov held consultations about the emerging crisis. On 1 September, Georgiev was among the ten opposition figures who signed a joint declaration to implement the Tarnovo Constitution and convene a Grand National Assembly to elect regents. They saw the situation as an opportunity to change the country's foreign policy course, but the government rejected their proposals. In the autumn of 1943, the Fatherland Front suffered a severe crisis and was on the verge of splitting over the publication of its first official bulletin. Kimon Georgiev, actively supported by Nikola Petkov, drafted an article with the organization's position on the Macedonian question, advocating the creation of a united and independent Macedonian state.
AGPs belong to large multigene families and are divided into several sub-groups depending on the predicted protein sequence. "Classical" AGPs include the GPI-AGPs that consist of a signal peptide at the N-terminus, a PAST-rich sequence of 100-150 aa and a hydrophobic region at the C-terminus that directs addition of a GPI-anchor; non GPI-AGPs that lack the C-terminal GPI signal sequence, Lysine(K)-rich AGPs that contain a K-rich region within the PAST-rich backbone and AG-peptide that have a short PAST-rich backbone of 10-15 aa (Figure 2). Chimeric AGPs consist of proteins that have an AGP region and an additional region with a recognised protein family (Pfam) domain. Chimeric AGPs include fasciclin-like AGPs (FLAs), phytocyanin-like AGPs (PAGs/PLAs, also known as early-nodulin-like proteins, ENODLs) and xylogen-like AGPs (XYLPs) that contain lipid-transfer-like domains. Several other putative chimeric AGP classes have been identified that include AG glycomotifs associated with protein kinase, leucine-rich repeat, X8, FH2 and other protein family domains. Other non-classical AGPs exist such as those containing a cysteine(C)-rich domain, also called PAC domains, and/or histidine(H)-rich domain, as well as many hybrid HRGPs that have motifs characteristic of AGPs and other HRGP members, usually extensin and Tyr motifs. AGPs are evolutionarily ancient and have been identified in green algae as well as Chromista and Glaucophyta.
Sources: en.wikipedia.org
=== ATP Cup === Zverev represented Germany at the ATP Cup in 2020 and 2021. At the debut of this tournament in 2020, he was on the team with Jan-Lennard Struff, Kevin Krawietz and Andreas Mies. In the group stage, where Germany met Australia, Canada and Greece, Zverev lost all three matches to Alex de Minaur, Denis Shapovalov and Stefanos Tsitsipas respectively. Germany did not advance to the next phase of the tournament, finishing third in the group. In 2021, Germany played again with the same lineup as the previous year. In the group they played against Canada and Serbia. Zverev won his first match against Denis Shapovalov. In their second meeting, he lost in singles to Novak Djokovic, but still played against him and Nikola Ćaćić in doubles while paired with Jan-Lennard Struff. Germany won that meeting, which allowed them to advance from first place in the group to the semifinals. There they ended up against Russia, where Zverev lost his match to Daniil Medvedev. Germany eventually lost the tie 2–1, allowing Russia to advance to the final.
Throughout the civil war, Cossacks sometimes fought as an independent ally, and other times as an auxiliary, of White armies. In South Russia, the Armed Forces of South Russia (AFSR) under General Anton Denikin relied heavily on conscripts from the Don and Kuban Cossack Hosts to fill their ranks. Through the Cossacks, the White armies acquired experienced, skilled horsemen that the Red Army was unable to match until late in the conflict. But the relationship between Cossack governments and the White leaders was frequently acrimonious. Cossack units were often ill-disciplined, and prone to bouts of looting and violence that caused the peasantry to resent the Whites. In Ukraine, Kuban and Terek Cossack squadrons carried out pogroms against Jews, despite orders from Denikin condemning such activity. Kuban Cossack politicians, wanting a semi-independent state of their own, frequently agitated against the AFSR command. In the Russian Far East, anticommunist Transbaikal and Ussuri Cossacks undermined the rear of Siberia's White armies by disrupting traffic on the Trans-Siberian Railway and engaging in acts of banditry that fueled a potent insurgency in that region. As the Red Army gained the initiative in the civil war during late 1919 and early 1920, Cossack soldiers, their families, and sometimes entire stanitsas retreated with the Whites. Some continued to fight with the Whites in the conflict's waning stages in Crimea and the Russian Far East. As many as 80,000–100,000 Cossacks eventually joined the defeated Whites in exile.
The iron atoms are coordinated to the protein through the carboxylate side chains of a glutamate and aspartate and five histidine residues. The uptake of O2 by hemerythrin is accompanied by two-electron oxidation of the reduced binuclear center to produce bound peroxide (OOH−). The mechanism of oxygen uptake and release have been worked out in detail. Hemocyanins carry oxygen in the blood of most mollusks, and some arthropods such as the horseshoe crab. They are second only to hemoglobin in biological popularity of use in oxygen transport. On oxygenation the two copper(I) atoms at the active site are oxidized to copper(II) and the dioxygen molecules are reduced to peroxide, O2−2. Chlorocruorin (as the larger carrier erythrocruorin) is an oxygen-binding hemeprotein present in the blood plasma of many annelids, particularly certain marine polychaetes.
=== Military and political escalation (1972–1976) === By December 1972, ZANLA had cached arms and established a vast underground network of informants and supporters in northeastern Rhodesia. As a result of the erosion of Portuguese authority in Mozambique's border provinces due to the Mozambican War of Independence, ZANLA was also able to establish external sanctuaries there. It was also in the process of cultivating a military alliance with the leading black nationalist movement in Mozambique, the Front for the Liberation of Mozambique (FRELIMO). On 21 December, a group of ZANLA insurgents under Rex Nhongo crossed into Rhodesia from Mozambique and raided an isolated commercial farm. In the successive months, this attack was followed by a succession of raids on white farmers throughout the northeastern districts of the country and resulted in several casualties among the security forces. The propaganda value of these raids, coupled with the success of ZANLA's politicisation campaign, denied intelligence to the security forces and furnished more recruits for the insurgents. In response, the Rhodesian security forces began coordinating operations in Mozambique with the Portuguese Army to intercept ZANLA insurgents before they could cross the border. The practical alliances between ZIPRA and MK, and later ZANLA and FRELIMO, prompted Rhodesia to look increasingly towards South Africa and Portugal for active assistance.
Sources: en.wikipedia.org
The names are often used interchangeably in casual writing, but they are not strictly identical. Modified GRF(1-29) refers to the unconjugated analogue carrying only the four substitutions. The version sold as CJC-1295 with DAC includes the albumin binding linker and clears much more slowly.
DAC stands for drug affinity complex, a term describing the maleimidopropionic acid linker. This group forms a covalent bond with the cysteine residue on serum albumin after administration. The resulting adduct is what extends the circulating half life from minutes to days.
No. It is entirely synthetic and does not correspond to any known endogenous peptide. The design starts from human growth hormone releasing hormone and introduces deliberate substitutions. Any biological effect comes from mimicking the natural hormone at its receptor.
It acts on the growth hormone-releasing hormone receptor found on pituitary somatotroph cells. Activation of that receptor triggers growth hormone release through a cyclic AMP dependent pathway.