Compound monograph
Cosyntropin (ACTH 1-24)
Cosyntropin is the synthetic 1-24 fragment of adrenocorticotropic hormone, the melanocortin ligand of the MC2R branch.
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Identity & nomenclature
Cosyntropin is the synthetic 1-24 fragment of adrenocorticotropic hormone, the melanocortin ligand of the MC2R branch.
Cosyntropin is ACTH(1-24). It is not full-length ACTH(1-39), not ACTH(4-10), and not alpha-MSH. A shared N-terminal sequence does not erase chain-length or terminal-processing differences, and 'ACTH' in a paper's abstract does not establish which preparation was used — some melanocortin experiments use capped or norleucine-substituted analogs. PubChem CID 16129617, the entry titled Cosyntropin, and CID 16129674 encode Lys15, Lys16, Arg17 and Arg18 as D-residues and leave the configuration of Ser1 undefined; this record therefore cites CID 16133751, which encodes the all-L chain.
Canonical name: Cosyntropin.
Declared aliases and development codes: Tetracosactide, ACTH(1-24), alpha 1-24 corticotropin.
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Molecular properties
| Molecular formula | C136H210N40O31S |
|---|---|
| Molecular mass | 2933.48 Da |
| CAS Registry Number | 16960-16-0 |
| PubChem CID | 16133751 |
| UNII | 72YY86EA29 |
| One-letter sequence | SYSMEHFRWGKPVGKKRRPVKVYP |
| Terminal groups | Free Ser1 amino terminus; Free Pro24 carboxyl terminus |
Twenty-four residues, all L, with a free N-terminus and a free C-terminal carboxyl. No acetylation, no amidation, no ring. Note the first thirteen residues are shared with alpha-MSH — the terminal processing is what differs.
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Structural characteristics
MC2R is the melanocortin receptor that responds to ACTH rather than to the shorter melanocortin pharmacophore, and its function depends on the accessory protein MRAP. Work fixing MRAP orientation establishes that the requirement is for MRAP acting on the EXTRACELLULAR face of the membrane, not merely for trafficking the receptor to the surface. Receptor-chimera experiments explicitly using ACTH(1-24) locate the regions responsible for ligand specificity and MRAP dependence. A structural study of an ACTH-bound MC2R-MRAP1 complex is cited as Class B: whether its experimental ligand is equivalent to unmodified cosyntropin is not established here.
Terminal features: Free Ser1 amino terminus, Free Pro24 carboxyl terminus.
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Molecular targets & mechanisms
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Analytical considerations
Confirmation needs the basic internal sequence and the Pro24 terminus, with explicit tests for Met4 versus a substituted analog and for the absence of an N-acetyl cap or C-terminal amide. An ACTH immunoassay may recognise several ACTH-containing fragments and does not establish 24-residue identity. Conversely, a negative result in an MC2R assay lacking functional MRAP is not evidence that the material is wrong.
Disagreements and mix-ups
Points where sources disagree about this compound's identity, or where a name or form is easily confused with another, as noted in this record. The discrepancy register quotes the passage for each one.
Sources disagree · this Library follows one source · Registry record
Cosyntropin's stereochemistry in PubChemOften mixed up · Name or substance
Cosyntropin, ACTH(1-24), vs other ACTH forms
What the studies reported
No verified findings are published for this record under Content Policy v1.
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Verified bibliography
Cited studies by type
The 3 papers this record cites, counted by the kind of work each reports. A count is the size of this record's selection, not of the research that exists, and says nothing about results, safety, effectiveness or approval.
A paper can report more than one kind of work. Each count opens those papers in the bibliography. Compare every record on the Evidence Map.
Reference 1
Adrenocorticotropic Hormone (ACTH) Responses Require Actions of the Melanocortin-2 Receptor Accessory Protein on the Extracellular Surface of the Plasma Membrane.Malik S, Dolan TM, Maben ZJ, Hinkle PM
The Journal of biological chemistry · 2015-09-30 · Journal Article
currentReference 2
Use of chimeric melanocortin-2 and -4 receptors to identify regions responsible for ligand specificity and dependence on melanocortin 2 receptor accessory protein.Hinkle PM, Serasinghe MN, Jakabowski A, Sebag JA, Wilson KR, Haskell-Luevano C
European journal of pharmacology · 2011-01-03 · Journal Article
currentReference 3
Structural basis of signaling regulation of the human melanocortin-2 receptor by MRAP1.Luo P, Feng W, Ma S, Dai A, Wu K, Chen X, Yuan Q, Cai X, Yang D, Wang MW, Eric Xu H, Jiang Y
Cell research · 2023-01-02 · Journal Article
current
Study models of these references
What kind of experiment each cited paper reports, taken from its abstract unless marked. Not a summary of results.
| Reference | Study models |
|---|---|
| Malik S et al. 2015 | Study models reported: in vitro · from the abstract |
| Hinkle PM et al. 2011 | Study models reported: in vitro · from the abstract |
| Luo P et al. 2023 | Study models reported: in vitro · from the abstract |
Record history
Published 2026-09-13.
- : Identity and nomenclature
- : Classification
Each entry names the parts of this record that changed on that date. Changes to links between records and to catalogue links are not listed. This history covers the tracked record fields; study findings are not listed here.
Cite this record: Purely Peptides Research Library. Cosyntropin (ACTH 1-24). Published 2026-09-13; updated 2026-10-12. https://purelypeptides.org/research/compounds/cosyntropin/
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Methodology & citation verification
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