GC-1 (Sobetirome / QRX-431) is a halogen-free diphenylmethane thyromimetic and thyroid hormone receptor beta (TRβ) agonist for nuclear receptor research. By binding TRβ1 with an affinity comparable to T3 and TRα1 with about 10-fold lower affinity, GC-1 activates the beta isoform selectively, a preference traced to its oxyacetic acid side chain and the Asn331 residue of the TRβ binding pocket. CAS 211110-63-3.
In stock
GC-1 (sobetirome, also called QRX-431 and [4-(4-hydroxy-3-isopropylbenzyl)-3,5-dimethylphenoxy]acetic acid; CAS 211110-63-3) is a synthetic, halogen-free thyromimetic: a diphenylmethane analog of thyroid hormone with an oxyacetic acid side chain. It is a thyroid hormone receptor agonist that is selective for the beta isoform (TRβ) over the alpha isoform (TRα). GC-1 is not a peptide and not an amino acid, even though many searches call it a “GC-1 peptide.” Its activity comes from how its two aromatic rings, its phenolic hydroxyl and its carboxylate fit the hormone-binding pocket of the receptor’s ligand-binding domain.
In receptor-binding work, GC-1 binds TRβ1 with an affinity comparable to the natural hormone T3 and binds TRα1 with about 10-fold lower affinity, and crystal structures of both isoforms bound to GC-1 trace that difference to one pocket residue, Asn331 in TRβ versus Ser277 in TRα (Bleicher et al., 2008, PMC2275733). That is what GC-1 does at the receptor level: it occupies and activates TRβ, a ligand-activated transcription regulator, in preference to TRα (Chiellini et al., 1998).
Batch-verified at Modern Aminos, GC-1 is supplied in one laboratory format:
Laboratories building nuclear receptor and metabolic pathway assay panels often place GC-1 next to other public reference listings such as DADA, as well as SLU-PP-332, BAM15, GW-501516 (Cardarine), and AICAR. For a closer look at whether GC-1 is a peptide, see Is GC-1 a Peptide? Sobetirome, the TRβ-Selective Thyromimetic, Explained.
| Compound Name | GC-1 (Sobetirome) |
|---|---|
| Research Category | Thyroid hormone receptor beta (TRβ) agonist; halogen-free diphenylmethane thyromimetic (phenoxyacetic acid); nuclear receptor and metabolic pathway reference compound |
| Quantity / Formats Offered | Dry-Fill Capsules |
| Synonyms / Alt Names | Sobetirome (INN, USAN); GC-1; GC 1; QRX-431; QRX431; [4-(4-hydroxy-3-isopropylbenzyl)-3,5-dimethylphenoxy]acetic acid; 3,5-dimethyl-4-(4′-hydroxy-3′-isopropylbenzyl)phenoxyacetic acid |
| CAS Number | 211110-63-3 |
| PubChem CID | 9862248 |
| ChEBI / ChEMBL ID | CHEBI:79988 / CHEMBL107400 |
| UNII | XQ31741E9Q |
| EPA DSSTox Substance ID | DTXSID60891557 |
| PDB Ligand Code | B72 |
| Chemical Formula | C20H24O4 |
| Molecular Weight | 328.4 g/mol |
| Exact Mass | 328.16746 Da |
| Stereochemistry | Achiral; no stereocenters |
| Computed Properties (PubChem) | XLogP3 4.9; TPSA 66.8 Ų; hydrogen-bond donors 2; hydrogen-bond acceptors 4; rotatable bonds 6 |
| IUPAC Name | 2-[4-[(4-hydroxy-3-propan-2-ylphenyl)methyl]-3,5-dimethylphenoxy]acetic acid |
| InChI | InChI=1S/C20H24O4/c1-12(2)17-9-15(5-6-19(17)21)10-18-13(3)7-16(8-14(18)4)24-11-20(22)23/h5-9,12,21H,10-11H2,1-4H3,(H,22,23) |
| InChIKey | QNAZTOHXCZPOSA-UHFFFAOYSA-N |
| SMILES Code | CC1=CC(=CC(=C1CC2=CC(=C(C=C2)O)C(C)C)C)OCC(=O)O |
Identity fields are drawn from PubChem CID 9862248; the current certificate is published in the Certificate of Analysis tab.
The biochemical targets and pathway logic of GC-1 in laboratory research include:
| Assay Parameter | GC-1 (Sobetirome) | T3 (3,3′,5-Triiodo-L-Thyronine) | Source |
|---|---|---|---|
| Binding affinity, TRβ1 | Comparable to T3 | Reference ligand | Bleicher 2008, Background |
| Binding affinity, TRα1 | About 10-fold lower than for TRβ1 | Similar for both isoforms | Bleicher 2008, Background and Results |
| TRβ-to-TRα affinity ratio | About 10-fold higher than T3 | Reference ligand | Zucchi 2020 |
| Crystal structure resolution, TRβ LBD complex | 2.55 Å | 2.30 Å | Bleicher 2008, Table 1 |
| Crystal structure resolution, TRα LBD complex | 1.85 Å (P212121 form); 2.50 Å (C2 form) | 1.87 Å | Bleicher 2008, Table 1 |
| Subtype-selective pocket residue | Asn331 anchors Arg282 to the GC-1 carboxylate (TRβ); Ser277 flips Arg228 (TRα) | Ser277 and Asn331 contact the T3 amino group | Bleicher 2008, Results |
Peer-reviewed literature on GC-1 (Sobetirome) and its thyroid hormone relatives centers on receptor binding, structural biology, structure-activity relationships, and synthetic chemistry:
To map thyroid hormone receptor selectivity and nearby metabolic pathway targets, researchers compare GC-1 against the natural hormone, its parent analog, its antagonist relatives, and other nuclear receptor and enzyme-level reference compounds, including several available at Modern Aminos:
| Compound / Reference | Primary Target Class | Core Mechanism of Action | Research Focus & Profile |
|---|---|---|---|
| GC-1 (Sobetirome) | TRβ-selective thyroid hormone receptor agonist; diphenylmethane thyromimetic | Binds TRβ1 with affinity comparable to T3 and TRα1 about 10-fold lower; oxyacetic acid carboxylate held by Arg282/Arg316/Arg320 | Isoform-selective nuclear receptor reference; CAS 211110-63-3 |
| T3 (3,3′,5-Triiodo-L-Thyronine) | Endogenous thyroid hormone receptor ligand; iodinated Thyronine | Binds TRα and TRβ with similar affinity; amino group contacts Ser277/Asn331 | Non-selective reference ligand; PubChem CID 5920 |
| DIMIT (3,5-Dimethyl-3′-isopropyl-L-Thyronine) | Halogen-free Thyronine analog; parent design of GC-1 | Lower TR affinity than GC-1 and not isoform-selective; biaryl ether and L-Alanine side chain | Side-chain structure-activity comparator; PubChem CID 108112 |
| NH-3 | Thyroid hormone receptor antagonist; 5′-substituted GC-1 scaffold | 5′-phenylethynyl extension converts the agonist scaffold into a full antagonist | Agonist-versus-antagonist structure-activity reference |
| SLU-PP-332 | Estrogen-related receptor (ERR) agonist | Activates a different nuclear receptor family (ERRα/β/γ) | Nuclear receptor pathway comparator from outside the TR family |
| DADA (Diisopropylamine Dichloroacetate) | Pyruvate dehydrogenase kinase (PDK) inhibitor salt | Keeps the pyruvate dehydrogenase complex in its active, dephosphorylated state | Enzyme-level metabolic pathway reference; CAS 660-27-5 |
Modern Aminos publishes a third-party certificate from Vanguard Laboratory, an A2LA-accredited lab (certificate #6377.01.01), for GC-1, and all applicable tests are performed on our products. If you want to buy sobetirome as a documented reference material, the certificate is in the Certificate of Analysis tab.
Neither. GC-1 is sobetirome, 2-[4-[(4-hydroxy-3-propan-2-ylphenyl)methyl]-3,5-dimethylphenoxy]acetic acid (C20H24O4, 328.4 g/mol, PubChem CID 9862248). It has no amino-acid residues and no peptide bonds. It was designed from thyroid hormone, an amino-acid-derived molecule, but the design replaced the amino-acid side chain with an oxyacetic acid side chain. The full explanation is in Is GC-1 a Peptide? Sobetirome, the TRβ-Selective Thyromimetic, Explained.
GC-1 from Modern Aminos is a laboratory research compound with a third-party certificate, not a dietary supplement. Chemically it is a synthetic thyromimetic, and it is classified by its thyroid hormone receptor pharmacology rather than by any supplement or performance label.
The target is the thyroid hormone receptor (TR), a member of the nuclear receptor superfamily of ligand-activated transcription regulators, encoded by two genes for TRα and TRβ. GC-1 is a high-affinity agonist that is selective in both binding and activation functions for TRβ over TRα (Chiellini et al., 1998). It binds TRβ1 with an affinity comparable to T3 and TRα1 with about 10-fold lower affinity (Bleicher et al., 2008).
GC-1 sits in the hormone-binding pocket of the receptor’s ligand-binding domain (LBD). Its phenolic hydroxyl hydrogen-bonds to a Histidine residue (His435 in TRβ), its two aromatic rings pack into a mostly apolar region, and its carboxylate is held by three Arginine residues (Arg282, Arg316 and Arg320 in TRβ) directly and through water-mediated hydrogen bonds (Bleicher et al., 2008). In TRβ, Asn331 hydrogen-bonds Arg282 and anchors it in one stable conformation that holds the GC-1 carboxylate.
It is the main source of TRβ selectivity. When the two structural features that separate GC-1 from its parent analog DIMIT were tested one at a time, the GC-1 analog carrying a biaryl ether kept selectivity comparable to GC-1, while the DIMIT analog carrying a methylene bridge was only slightly selective, showing that the oxyacetic acid side chain is critical (Yoshihara et al., 2003). Crystal structures point to the same feature: the oxyacetic acid ether oxygen and the absence of an amino group relative to T3 (Bleicher et al., 2008).
Three changes turn T3 (3,3′,5-Triiodo-L-Thyronine) into GC-1: the three iodines are replaced with methyl and isopropyl groups, the biaryl ether oxygen is replaced with a methylene bridge, and the amino-acid side chain is replaced with an oxyacetic acid side chain (Chiellini et al., 1998). T3 binds both TR isoforms with similar affinity, while GC-1 favors TRβ; the TRβ-to-TRα affinity ratio is about 10-fold higher for GC-1 than for T3 (Zucchi, 2020). GC-1 also has no stereocenter, while T3 has one (PubChem CID 5920).
PubChem CID 9862248 lists GC-1 as sobetirome (its INN and USAN name), GC 1, and QRX-431, with CAS 211110-63-3, UNII XQ31741E9Q, ChEBI CHEBI:79988, ChEMBL CHEMBL107400, and DSSTox DTXSID60891557. In Protein Data Bank crystal structures the ligand code is B72. The InChIKey QNAZTOHXCZPOSA-UHFFFAOYSA-N is the quickest single check of identity.
Modern Aminos supplies GC-1 in one format: dry-fill capsules. A loose powder or liquid format is not offered for this listing.
They act at different control points. GC-1 is a nuclear receptor ligand that activates TRβ, SLU-PP-332 is an estrogen-related receptor (ERR) agonist from another nuclear receptor family, and DADA is a dichloroacetate salt that inhibits pyruvate dehydrogenase kinase (PDK), an enzyme rather than a receptor. See Is DADA a Peptide? Diisopropylamine Dichloroacetate Explained for that compound.
All applicable tests are performed on our products. The current third-party Vanguard Laboratory certificate (A2LA #6377.01.01) is published in the Certificate of Analysis tab, and upcoming batches receive expanded testing across two ISO-certified labs, covering Sterility, Identity, Purity, Endotoxin, Heavy Metals, Mass, Residual Solvents, Fentanyl and Conformity. The identity fields on this page (CAS, InChI, InChIKey, SMILES) come from PubChem CID 9862248.
Keep the capsule bottle sealed, cool, dry, and away from light. Follow the label on each lot. No storage temperature is printed on the current Vanguard certificate, so none is given here.
DISCLAIMER: All compounds and research materials provided by Modern Aminos are strictly for laboratory and research use only. They are not approved for human consumption by the Food and Drug Administration (FDA). No products are approved for oral, sublingual, nor in vivo use. These products should not be used for any form of in vivo experimentation or for any other non-laboratory purpose. Any violation or indication of human or animal use will result in immediate removal from being able to purchase products in the future. By purchasing these products, you acknowledge that they will be used exclusively within a controlled and qualified research environment.
Capsule products are not intended for time-release and are for transport only.
DISCLAIMER: All compounds and research materials provided by Modern Aminos are strictly for laboratory and research use only. They are not approved for human consumption by the Food and Drug Administration (FDA). No products are approved for oral, sublingual, nor in vivo use. These products should not be used for any form of in vivo experimentation or for any other non-laboratory purpose. Any violation or indication of human or animal use will result in immediate removal from being able to purchase products in the future. By purchasing these products, you acknowledge that they will be used exclusively within a controlled and qualified research environment.
