Everything below concerns Pro-Gly-Pro. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
== L == Lamina A layer of neurons in a neural structure. In the spinal cord and cerebral cortex, laminae are functionally and anatomically distinct. Lateral geniculate nucleus (LGN) A relay center in the thalamus that receives input from the retina and sends visual information to the visual cortex. Lateral inhibition A neural mechanism in which an excited neuron reduces the activity of its neighbors. Enhances contrast in sensory systems such as vision and touch. Lateral sulcus A deep groove in the cerebral cortex that separates the frontal lobe and parietal lobe from the temporal lobe. Learning The acquisition of new knowledge or skills through experience, study, or teaching. In neuroscience, learning is linked to synaptic plasticity and neural circuit changes. Learning A neurobiological process through which experience induces lasting changes in the nervous system, leading to the acquisition or modification of behavior, knowledge, or skills. Lentiform nucleus A structure within the basal ganglia composed of the putamen and globus pallidus, involved in motor control and learning. Lesion Damage or abnormal change in brain tissue, caused by injury, stroke, disease, or surgery. Lesion studies are used to investigate brain function. Levodopa A precursor to dopamine used in the treatment of Parkinson’s disease. It crosses the blood–brain barrier and is converted to dopamine in the brain. Limbic system A group of interconnected brain structures involved in emotion, motivation, memory, and olfaction. Includes the amygdala, hippocampus, and cingulate cortex.
xv. ISBN 978-1-62683-043-1. Retrieved March 22, 2021. Siddiqi, Asif A. (2000). Challenge to Apollo: the Soviet Union and the space race, 1945–1974 (PDF). Washington, D.C.: National Aeronautics and Space Administration, NASA History Div. Retrieved February 10, 2026. Siddiqi, Asif A. (2003). Sputnik and the Soviet Space Challenge. Gainesville: University Press of Florida. ISBN 0-8130-2627-X. Siddiqi, Asif A. (2003). The Soviet Space Race with Apollo. Gainesville: University Press of Florida. ISBN 0-8130-2628-8. Stocker, Jeremy (2004). Britain and Ballistic Missile Defence, 1942–2002. London: Frank Case. pp. 12–24. ISBN 0-7146-5696-8. Swenson, Loyd S. Jr.; Grimwood, James M.; Alexander, Charles C. (1966). This New Ocean: A History of Project Mercury. NASA. ISBN 1-934941-87-5. Retrieved January 8, 2023. Turnhill, Reginald (2004). The Moonlandings: An Eyewitness Account. New York: Cambridge University Press. ISBN 0-521-81595-9. Pervushin, Anton (2011). 108 minutes which changed the world (in Russian). Эксмо. ISBN 978-5-699-48001-2.
== Species complex == While traditionally described as a cosmopolitan species, recent genetic research has identified Octopus vulgaris as a species complex. There are currently six recognized members of the Octopus vulgaris species complex. Each member of the complex is associated with specific geographic regions, often associated with continental coastlines.
In 1959, Nikita Khrushchev launched an anti-religious campaign. Of the 50 churches that were operating in Moscow in 1959, 30 were closed and six demolished. On 8 May 1965, the 20th anniversary of the Soviet victory in World War II, Moscow was awarded the honorary title of Hero City. The Moscow Ring Road (MKAD) was opened in 1961. It had four lanes running 109 kilometers (68 mi) along city borders. The MKAD marked the administrative boundaries of the city until the 1980s, when outlying suburbs beyond the ring road were incorporated. In 1980, Moscow hosted the Summer Olympic Games, which were boycotted by the United States and other Western countries because the Soviet Union invaded Afghanistan in 1979. In 1991, Moscow was the scene of a coup attempt by conservative communists opposed to the liberal reforms of Mikhail Gorbachev.
Sources: en.wikipedia.org
It is often observed that several compounds are found to have some degree of activity, and if these compounds share common chemical features, one or more pharmacophores can then be developed. At this point, medicinal chemists will attempt to use structure–activity relationships (SAR) to improve certain features of the lead compound:
=== Cell signaling and function === As a cell adhesive substrate, CCN1 induces the activation of focal adhesion kinase, paxillin, RAC, and sustained activation of MAPK/ERK1-2. In macrophages, CCN1 also activates the transcription factor NFκB and stimulates M1 polarization. CYR61 activates Akt signaling in thymic epithelial cells, promoting their proliferation and thus thymic size growth. CCN1 has potent angiogenic activity upon endothelial cells and induces neovascularization, first demonstrated in a corneal micropocket implant assay and subsequently confirmed in a rabbit ischemic hindlimb model. CCN1 also accelerates and promotes the chondrogenic differentiation of mouse limb bud mesenchymal cells, and stimulates osteoblast differentiation but inhibits osteoclastogenesis. CCN1 is a strong inducer of reactive oxygen species accumulation in fibroblastic cells, and this activity underlies many CCN1-induced apoptosis and senescence. CYR61 is able to support cell adhesion, stimulate cell migration, promote growth factor-induced cell proliferation and differentiation in some cell types, promote apoptosis in synergy with TNF family cytokines, and induce cellular senescence in fibroblasts.
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Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.