A practical reference on thymosin beta-4: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-18 and is reviewed periodically as new material appears.
The most frequently cited identity is a seven-residue fragment with the sequence LKKTETQ, taken from the actin-binding domain of the parent protein. A separate molecule, N-acetyl-seryl-aspartyl-lysyl-proline, often shortened to Ac-SDKP, derives from the same protein's N-terminal region and appears in overlapping literature. Reported molecular masses therefore differ between sources, and a mass value on its own does not establish which fragment is present. Confirmation requires a defined sequence rather than a single number.
Research interest in thymosin beta-4 fragments centres on actin sequestration, cell migration and tissue repair models. Most published work uses cultured cells or animal wound and cardiac preparations, and findings are generally described as preliminary. No fragment of this protein has been approved as a therapeutic product by major regulators. Reviews of the field note inconsistent dosing, delivery routes and outcome measures across studies, which complicates direct comparison. The material is best understood as a laboratory reagent with an active but unresolved research literature.
TB-500 is a synthetic seven-amino-acid peptide with the sequence LKKTETQ, corresponding to residues 17 through 23 of the protein thymosin beta-4. The N-terminus is typically acetylated in the described form, giving a monoisotopic mass near 888.5 Da and an average mass of about 889 Da. The designation TB-500 is a catalogue label rather than a formal chemical name, and the same sequence appears in the literature under several alternative abbreviations. It is handled as a research reagent rather than a pharmaceutical product.
Thymosin beta-4 is a 43-residue actin-binding protein found in most mammalian cell types, where it participates in cytoskeletal regulation and cell migration. TB-500 represents only a short fragment of that protein and does not include the remaining residues. Whether the isolated fragment reproduces the full range of activities reported for the intact protein remains an open question. Researchers commonly treat the two as related but distinct entities when comparing results.
Published work involving this sequence spans actin-binding assays, cell-migration studies, wound-healing models, and cardiovascular or musculoskeletal experiments. Much of the biological rationale derives from in vitro systems and animal models, and the number of controlled human studies is small. Reported outcomes vary across preparations, doses, and routes, which complicates comparison between studies. Reviews generally describe the evidence base as preliminary rather than settled. Mechanistic explanations are often proposed by analogy to the parent protein rather than demonstrated directly.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white lyophilized powder | Typical form for short synthetic peptides |
| Solubility class | Freely soluble in water and aqueous buffer | Dissolution aided by gentle mixing, not vigorous shaking |
| Typical storage temperature | −20 °C, desiccated | −80 °C used for long-term holding |
| Common analytical method | Reverse-phase HPLC with UV detection near 214 nm | Identity confirmed separately by mass spectrometry |
| Common synonyms | Thymosin beta-4 fragment; TB4 fragment | Naming varies between suppliers and publications |
TB-500 is a synthetic seven-residue peptide whose sequence, LKKTETQ, matches the N-terminal actin-binding region of thymosin beta-4. It is usually supplied in an N-terminally acetylated form, a modification that blocks the free amino terminus and can influence behavior in solution. In the research literature the same sequence appears under several names, including thymosin beta-4 fragment and shortened thymosin beta-4. Because it is a short peptide rather than the full 43-residue parent protein, its measured properties differ from those reported for thymosin beta-4 as a whole, and the two are not interchangeable in experimental design.
Thymosin beta-4 itself is a small, widely expressed protein that sequesters monomeric actin and participates in cell migration, angiogenesis, and tissue repair. Researchers have examined the shortened fragment as a possible mimic of some of these activities, reasoning that the actin-binding motif lies within the first few residues. Binding to monomeric actin has been observed in cell-free systems. Whether the fragment reproduces the broader effects of the full protein in living tissue remains an open question, and findings from animal models are frequently cited without a clear bridge to human physiology.
Discussion of TB-500 appears in several distinct literatures that rarely cite one another. Peer-reviewed studies usually describe in vitro assays or small animal experiments and are cautious about extrapolation. Veterinary and sports communities circulate anecdotal reports with limited methodological detail. Commercial listings add a third layer, often using the name interchangeably with thymosin beta-4 even though the two molecules differ in size and sequence. Regulatory status varies by country, and the compound is not a licensed medicine in most jurisdictions, so readers comparing sources should check which molecule and which purity each source actually describes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
The patches are also included in the game version sold on the GOG.com distribution service. Boyarsky voiced his support for unofficial patches, saying, "they've found the stuff that we hoped people would find about the game, in terms of the different paths you can take and how it played differently for every class." Boyarsky said that while he would have preferred that the game was more successful at launch, that people were still playing and modifying it made Troika's efforts feel more "worthwhile". Schaffer released a remastered version of his score through Milan Records in October 2019, including eight previously unreleased tracks. The score could be purchased on compact disc, digital download, and a blood-red vinyl record version with a marbled, black smoke effect housed in a custom sleeve.
== Medical uses == The 2022 American Diabetes Association (ADA) standards of medical care in diabetes include SGLT2 inhibitors as a first line pharmacological therapy for type 2 diabetes (usually together with metformin), specifically in patients with chronic kidney disease, cardiovascular disease or heart failure. A systematic review and network meta-analysis comparing SGLT-2 inhibitors, GLP-1 agonists, and DPP-4 inhibitors demonstrated that use of SGLT2 inhibitors was associated with a 1% reduction in death compared with placebo or no treatment. Another systematic review discussed the mechanisms by which SGLT-2 inhibitors improve cardio-renal function in patients with type 2 diabetes, emphasizing the impacts in improving neural tone. A meta-analysis including 13 cardiovascular outcome trials found that SGLT-2 inhibitors reduce the risk for three-point major adverse cardiovascular events (MACE), especially in subjects with an estimated glomerular filtration rate (eGFR) below 60 ml/min, whereas GLP-1 receptor agonists were more beneficial in persons with higher eGFR. Likewise, the risk reduction due to SGLT-2 inhibitors was larger in populations with a higher proportion of albuminuria, but this relationship was not observed for GLP-1 receptor agonists. This suggests a differential use of the two substance classes in patients with preserved and reduced renal function or with and without diabetic nephropathy, respectively. Two reviews have concluded that SGLT2 inhibitors benefit patients with atherosclerotic major adverse cardiovascular events.
The Chinese People's Armed Police Coast Guard Bureau, also abbreviated as China Coast Guard is the agency for maritime search and rescue and law enforcement in the territorial waters of the People's Republic of China. The China Coast Guard was formerly the maritime branch of the People's Armed Police (PAP) Border Security Force under the Ministry of Public Security until 2013. In March 2013, China announced it would form a unified Coast Guard commanded by the State Oceanic Administration. This renewed Coast Guard has been in operation since July 2013. As of 1 July 2018, the China Coast Guard was transferred from civilian control of the State Council and the State Oceanic Administration, to the People's Armed Police, ultimately placing it under the command of the Central Military Commission (CMC). According to Joel Wuthnow of the Institute for National Strategic Studies, the Coast Guard Command within the People's Armed Police possibly is of Corps Leader Grade, led by a Commandant who usually holds the rank of major general. In June 2018, China Coast Guard was granted maritime rights and law enforcement akin civilian law enforcement agencies in order to carry out contrast of illegal activities, keep peace and order, as well as safeguarding security at sea, when performing duties related to the use of marine resources, protection of marine environment, regulation of fishery, and anti-smuggling. There are currently 3 regional bureaus:
Sources: en.wikipedia.org
=== miRNA === MicroRNAs (miRNAs) have complementary sequences in the 3' UTR and 5' UTR of target mRNAs of protein-coding genes, and cause mRNA cleavage or repression of translational machinery. In diseased vascular vessels, miRNAs are dysregulated and highly expressed. miR-33 is found in cardiovascular diseases. It is involved in atherosclerotic initiation and progression including lipid metabolism, insulin signaling and glucose homeostatis, cell type progression and proliferation, and myeloid cell differentiation. They found in rodents that the inhibition of miR-33 raises HDL-C levels, and miR-33 expression is down-regulated in humans with atherosclerotic plaques. miR-33a and miR-33b are located on intron 16 of human sterol regulatory element-binding protein 2 (SREBP2) gene on chromosome 22 and intron 17 of SREBP1 gene on chromosome 17. miR-33a/b regulates cholesterol/lipid homeostasis by binding in the 3'UTRs of genes involved in cholesterol transport, such as ATP binding cassette (ABC) transporters, and enhances or represses their expression. Studies have shown that ABCA1 mediates cholesterol transport from peripheral tissues to Apolipoprotein-1. It is also important in the reverse cholesterol transport pathway, where cholesterol is delivered from peripheral tissue to the liver, where it can be excreted into bile or converted to bile acids before excretion. Therefore, ABCA1 prevents cholesterol accumulation in macrophages. By enhancing miR-33 function, ABCA1 levels decrease, leading to decreased cellular cholesterol efflux to apoA-1.
==== Other activities ==== In addition to the opioid receptors, naltrexone binds to and acts as an antagonist of the opioid growth factor receptor (OGFR) and toll-like receptor 4 (TLR4). It has been proposed that low doses of naltrexone (1 to 5 mg/day) produce TLR4 antagonism, and standard clinical doses (50 to 100 mg/day) exert opioid receptor and OGFR antagonism. The interactions of naltrexone with TLR4 are claimed to be involved in the therapeutic effects of low-dose naltrexone.
== History == Omadacycline was invented at Tufts University School of Medicine by a research team led by Mark L. Nelson with Mohamed Ismail while at Tufts and Kwasi Ohemeng and Laura Honeyman at Paratek Pharmaceuticals, Boston. The team applying their chemistry methods to the tetracycline scaffolds created over 3000 new derivatives, leading to the novel third-generation compounds omadacycline and sarecycline.
Sources: en.wikipedia.org
TB-500 is a trade-style label for a synthetic peptide connected to thymosin beta-4. It is sold mainly through research-chemical channels and is not a single chemically defined product across suppliers.
Not necessarily. Some vendors use the name for the full 43-residue protein, while others apply it to a short actin-binding fragment or to a related tetrapeptide. The sequence should be confirmed from documentation rather than assumed from the label.
No thymosin beta-4 fragment holds marketing approval as a medicine in major jurisdictions. Material offered for sale is typically labelled for laboratory research only.
No. TB-500 is a short synthetic peptide matching residues 17 to 23 of thymosin beta-4, while the parent protein contains 43 residues. The fragment lacks the rest of the protein sequence, so the two are related but not identical.