| Size | Price | Stock | Qty |
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| 1mg |
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| 5mg |
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| 10mg |
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| 50mg |
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| Other Sizes |
| Targets |
SRC-1 NR box peptide acetate targets the activation function-2 (AF-2) domain of nuclear receptors (NRs), particularly estrogen receptor alpha (ERalpha) and beta (ERbeta), as well as androgen receptor (AR), glucocorticoid receptor (GR), and progesterone receptor (PR). The LXXLL (leucine-rich) motif binds to the hydrophobic groove of the ligand-bound NR, facilitating the recruitment of SRC-1 to the transcriptional complex. This interaction is essential for coactivator-mediated transcription. The peptide acts as a competitor for the endogenous SRC-1 coactivator binding.
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| ln Vitro |
In vitro, SRC-1 NR box peptide acetate inhibits the interaction between nuclear receptors and full-length SRC-1. In a fluorescence polarization (FP) binding assay, the peptide (1-100 uM) is incubated with FITC-labeled ERalpha AF-2 and increasing concentrations of the unlabeled peptide. The IC50 for displacement of the peptide from ERalpha is typically 1-10 uM. In a GST pull-down assay, GST-SRC-1 is incubated with radiolabeled ERalpha ligand-binding domain (LBD) in the presence of the peptide (10 uM). The peptide blocks the interaction by 50-70%. It does not have cytotoxic effects.
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| ln Vivo |
In vivo, SRC-1 NR box peptide acetate is not a drug and is not administered to animals for therapeutic purposes. It is a research reagent used in ex vivo experiments. In microinjection studies (Xenopus oocytes), the peptide is co-injected with nuclear receptor expression vectors to block transcriptional activation. It is not used in mammalian disease models.
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| Enzyme Assay |
General protocol for in vitro enzyme/receptor binding (non-cellular): For a fluorescence polarization competition assay, incubate 20 nM FITC-labeled peptide (containing the LXXLL motif from SRC-1) with 50 nM recombinant human ERalpha LBD (ligand-binding domain) in 20 mM Tris-HCl (pH 7.5), 150 mM NaCl, 0.01% Tween-20, and 1 uM 17beta-estradiol. Add increasing concentrations of unlabeled SRC-1 NR box peptide acetate (0.1-100 uM). Incubate at 4degC for 2 h. Measure fluorescence polarization (Ex 485 nm, Em 530 nm). Calculate the IC50 by plotting mP vs. log[peptide]. The IC50 for the unlabeled peptide is typically 2-8 uM. For a GST pull-down assay, incubate 1 ug of GST-SRC-1 with 0.5 ug of His-ERalpha LBD and 10 uM peptide in binding buffer for 2 h. Pull down with glutathione beads, elute, and run SDS-PAGE. Stain with Coomassie or blot with anti-His antibody. The peptide reduces the band intensity of His-ERalpha.
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| Cell Assay |
General protocol for in vitro cell-based experiments: For a mammalian two-hybrid assay, transfect HEK293T cells with a Gal4-ERalpha fusion vector, a VP16-SRC-1 fusion vector, and a Gal4-luciferase reporter. Treat cells with 10 nM 17beta-estradiol and 1-10 uM of SRC-1 NR box peptide acetate (transfected or added via lipofectamine). After 24 h, measure luciferase activity. The peptide will inhibit the interaction and reduce luciferase signal by 50% at 5 uM. For cytotoxicity, treat cells with peptide (1-50 uM) for 48 h, perform MTT assay. No toxicity observed. For cellular uptake, the peptide is typically co-transfected or conjugated to a cell-penetrating peptide (CPP), as the free peptide is not cell-permeable.
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| Animal Protocol |
General protocol for in vivo animal experiments: Not applicable. The peptide is not administered in vivo due to rapid degradation and lack of cell permeability. It is used in microinjection of Xenopus oocytes. Oocytes are injected with 10 nL of a mixture containing 1 ng/uL of nuclear receptor mRNA and 100 uM of peptide. After 24 h, measure transcriptional activity via a reporter construct. The peptide blocks coactivator recruitment.
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| ADME/Pharmacokinetics |
General pharmacokinetic properties: SRC-1 NR box peptide acetate is a 14-amino acid peptide (MW ~1500-1800 Da). It is soluble in water (due to acetate salt). It is not a drug, so no ADME data exist. In plasma, it would be rapidly degraded by proteases (t1/2 < 30 min) and has very low oral bioavailability. For storage, the lyophilized powder is stable for up to 2 years at -20degC. Stock solutions (1 mM) in water or PBS can be stored at -80degC for 6 months. Avoid repeated freeze-thaw cycles.
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| Toxicity/Toxicokinetics |
General toxicity profile: SRC-1 NR box peptide acetate is a research peptide and generally considered low toxicity. At the concentrations used (nM-uM), it is not cytotoxic to cultured cells. Standard laboratory safety precautions (gloves, lab coat) are sufficient. It is not a controlled substance. For research use only.
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| References | |
| Additional Infomation |
SRC-1 NR box peptide acetate is also known as Steroid Receptor Coactivator-1 NR box peptide. The LXXLL motif is critical for coactivator recruitment and is a validated drug target for endocrine therapy (e.g., blocking ER signaling in breast cancer). The peptide is a positive control in coactivator recruitment assays. It is also used to assess the specificity of small molecule inhibitors of NR-coactivator interactions. For research and analytical use only.
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| Molecular Formula |
C79H136N26O21.XC2H4O2
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| Molecular Weight |
1786.09 (free base)
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| Related CAS # |
SRC-1 NR box peptide
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| Sequence |
Leu-Thr-Glu-Arg-His-Lys-Ile-Leu-His-Arg-Leu-Leu-Gln-GluLTERHKILHRLLQE
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| Appearance |
Solid powder
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO : ~100 mg/mL (with sonication)
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| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). View More
Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] Oral Formulations
Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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