ACE-031, a soluble activin receptor type IIB fusion protein
CAS 1169766-01-1Not applicableApproximately 110 kDa for the disulfide-linked homodimer. Recombinant Fc fusion proteins show mass heterogeneity arising from glycosylation, so the observed mass is a distribution rather than a single value. Net content is reported on a per-vial basis on the certificate of analysis published on this page.Peptide complexLyophilized powder
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Lot ACE1 · 1 mg vial · Freedom Diagnostics · reported 9 June 2026 . The bar shows where the reported result falls against Astramide’s published release criterion. The notch marks the criterion.
Within criterionAbove criterionNot on this COA
Test
Method
Criterion
Result
Result vs criterion
Status
Identity
LC-MS
LC-MS match to the labelled compound
Confirmed
WITHIN SPEC
Chromatographic purity
HPLC-UV
at or above 98.0%
99.09%
95at or above 98.0%100
WITHIN SPEC
Net content
HPLC-UV
1.28 mg
80120
REPORTED
Endotoxin
LAL, USP <85>
below the 0.05 EU/mL assay sensitivity
Pass, 2 of 2 at ≤0.05 EU/mL
WITHIN SPEC
Appearance
Visual
white lyophilized powder
White Lyophilized Powder
WITHIN SPEC
Values are reported per vial or bottle unless otherwise noted. Every figure here is taken from the batch Certificate of Analysis and nothing else.
Freedom Diagnostics · 1 page · served inline, not a screenshot
Quick reference
How to read this report
Same six keys on every Astramide product page. Only the values change.
1Lot numberMatch it to the number printed on your product label. If they differ, this report is not for your product.
2IdentityMass spectrometry confirms the molecule is the one on the label. It conforms or it does not. There is no partial result.
3Chromatographic purityThe share of the material that is the target peptide. A purity figure quoted without a method is not a purity figure.
4Net contentHow much compound is in each vial or bottle, as measured by the laboratory. A different question from purity.
5EndotoxinMeasured against a ceiling, not a floor. Sensitivity differs by laboratory, so results are not compared across labs.
6Laboratory, method, dateWho ran it, on what instrument, and when. A report with no named laboratory or no date is not a report.
Molecular profile
ACE-031, in structural terms.
Sequence
ACE-031 is a dimeric fusion protein comprising the extracellular ligand-binding domain of human activin receptor type IIB (ActRIIB) joined to the Fc region of human immunoglobulin G1. The construct is expressed recombinantly and assembles as a disulfide-linked homodimer through the Fc hinge. As a multi-domain recombinant protein of approximately 110 kDa, it is described by construct architecture rather than by a short sequence string. Sequence-level characterisation data is available on request to qualified research purchasers.
Molecular formula
Not applicable — ACE-031 is a recombinant fusion protein, not a small molecule or synthetic peptide. It is not assigned an empirical molecular formula. Identity for each lot is confirmed by mass spectrometric match to the labelled compound and reported on the certificate of analysis published on this page.
Molecular weight
Approximately 110 kDa for the disulfide-linked homodimer. Recombinant Fc fusion proteins show mass heterogeneity arising from glycosylation, so the observed mass is a distribution rather than a single value. Net content is reported on a per-vial basis on the certificate of analysis published on this page.
CAS number
1169766-01-1
Structure type
Peptide complex
Primary molecular target
Ligands of the TGF-β superfamily that signal through activin receptor type IIB — including myostatin (GDF-8), activin A, and GDF-11The construct functions as a soluble ligand trap. Rather than binding a receptor, it sequesters circulating ligands before they can engage cell-surface ActRIIB, preventing downstream SMAD2/3 phosphorylation. This trap mechanism is mechanistically distinct from receptor antagonism.
Physical form
Lyophilized powder
ACE-031 continues to be relevant to experimental biology involving ActRIIB ligand interactions and TGF-β superfamily signaling.Its engineered soluble receptor structure allows researchers to investigate ligand sequestration and downstream signaling associated with myostatin, activins, and related signaling proteins in controlled experimental models.
Research profile
Where ACE-031 appears in the literature.
Protein Biochemistry; Receptor Pharmacology; Musculoskeletal Research; TGF-β Superfamily Signalling
Research applications
Published experimental use of soluble ActRIIB-Fc constructs includes:
Ligand binding and sequestration assays against myostatin, activin A and GDF-11
SMAD2/3 phosphorylation assays in responsive cell lines
Reporter assays using SMAD-responsive promoter constructs
Selectivity profiling across TGF-β superfamily ligands
Preclinical studies in rodent models of muscle biology
Biophysical characterisation of Fc fusion protein constructs
These areas describe experimental research contexts and do not establish therapeutic efficacy or safety in humans.
Experimental systems
Experimental systems reported in this literature include:
C2C12 myoblast and myotube cultures
HEK293 cells transfected with SMAD-responsive reporter constructs
Purified recombinant ligand and receptor preparations
Surface plasmon resonance systems for binding kinetics
Rodent models used in published preclinical work
Specific assays
Assay formats reported in this literature include:
Surface plasmon resonance for binding affinity and kinetics
SMAD-responsive luciferase reporter assays
Western blot for phosphorylated SMAD2/3
ELISA for free versus bound ligand quantification
Size-exclusion chromatography and SDS-PAGE for construct integrity
Glycan profiling by mass spectrometry
Measured endpoints
Endpoints reported in published research on ActRIIB-Fc constructs include:
Binding affinity (KD) and association and dissociation rate constants per ligand
SMAD-responsive reporter activity relative to control
Phosphorylated SMAD2/3 signal relative to total SMAD
Free ligand concentration following sequestration
Monomer, dimer and aggregate distribution by size-exclusion chromatography
Research use only. Not for human or animal consumption.
ACE-031 has been investigated in controlled experimental systems involving TGF-β superfamily signaling and ActRIIB-associated pathways. Research areas include:
Activin receptor type IIB pathway research
Myostatin-associated signaling
TGF-β superfamily ligand interactions
Skeletal-muscle biology
Cellular growth and differentiation pathways
Ligand-receptor binding models
Protein signaling mechanisms
ActRIIB pathway modulation
These observations relate to experimental research and do not establish therapeutic efficacy or safety for human use.
These are published research systems. They do not describe approved clinical applications, and they do not establish efficacy or safety in humans.
Cited literature
Antfolk D et al., 2025. Molecular mechanism of Activin receptor inhibition by DLK1. Nat Commun. PMID 40593645. https://pubmed.ncbi.nlm.nih.gov/40593645/
Evidence level
The ActRIIB ligand trap mechanism is well characterised in published biochemical and preclinical work, including binding kinetics and downstream signalling. Development of this specific construct was discontinued, and published human clinical data is limited. Statements on this page describe experimental systems only and make no claim about outcomes in humans.
Handling and storage
As supplied
Lyophilized powder in a sealed vial. Held in laboratory-rated freezers from arrival to shipment.
Storage
Store per the conditions printed on the vial label. Avoid heat, moisture and repeated temperature cycling.
Handling
For qualified professionals in controlled laboratory environments, following validated laboratory procedures.
Frequently asked questions
About this compound and its batch data.
What purity did this ACE-031 batch achieve?
Lot ACE1 was analysed by Freedom Diagnostics and returned chromatographic purity of 99.09% by HPLC with UV detection coupled to mass spectrometry. Identity was confirmed by mass spectral match. The full certificate is published on this page, and every figure shown here is taken from it.
How much ACE-031 is in the vial?
The laboratory measured 1.28 mg, which is 128% of the label claim. Net content is reported on a per-vial basis. Astramide publishes the measured figure rather than the label claim, whether it falls above or below.
Was this ACE-031 batch tested for endotoxins?
Yes. Endotoxin testing was performed using the Limulus Amebocyte Lysate assay in accordance with USP , and this batch returned Pass, 2 of 2 at ≤0.05 EU/mL. The result appears on the certificate published on this page.
How should ACE-031 be stored for research use?
As supplied, the lyophilized powder should be held at -20°C and protected from light and moisture. Once reconstituted, store at 2-8°C and use within 14 to 30 days. Avoid repeated freeze-thaw cycles and follow the handling procedures appropriate to your laboratory.
What is the difference between research-grade and pharmaceutical-grade ACE-031?
These are separate classifications. Research-grade material is supplied for laboratory research use only and is not intended for human or animal consumption. Pharmaceutical-grade is an FDA classification that applies to drugs manufactured for human use. Astramide supplies research-grade material only.
How can I verify this ACE-031 certificate independently?
The certificate was issued by Freedom Diagnostics under lot ACE1, laboratory reference 2606080470. Quote that reference to the laboratory directly. The same document is published here in full, and is not summarised or reformatted by Astramide.
Research use only
This product is intended strictly for in-vitro laboratory research conducted by qualified professionals.
It is not intended for human or animal consumption, clinical use, or therapeutic application.
The statements on this page have not been reviewed by the FDA. These research peptides are not intended
to diagnose, treat, cure, or prevent any disease. Research Use Only.
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Know what's in it before you order.
Every Astramide batch is tested by an independent US lab. The report goes public before the batch goes on sale, so you can check the numbers first.
Independent US lab test on every batch
Full report published before it goes on sale
Kept frozen, shipped from Austin, Texas
GLP-3RLot 2026/02 · May 8, 2026
>99.9%purity by HPLC-UV/MS
90%Minimum 98.0%100%
Identity: Confirmed by mass specEndotoxin: Below 0.5 EU/mL
Pro Series
Pro Series
