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    • G-1 (CAS 881639-98-1): Selective GPR30 Agonist for Rapid ...

    2026-01-20

    G-1 (CAS 881639-98-1): Selective GPR30 Agonist for Rapid Estrogen Signaling Research

    Executive Summary: G-1 (CAS 881639-98-1) is a highly selective agonist for GPR30/GPER1, enabling precise dissection of rapid, non-genomic estrogen signaling distinct from ERα and ERβ (Wang et al. 2021). G-1 exhibits nanomolar affinity (Ki ≈ 11 nM) and robust functional potency (EC50 for calcium mobilization = 2 nM) in relevant cell systems (APExBIO). It inhibits breast cancer cell migration and demonstrates cardioprotective effects in preclinical heart failure models. These actions are mechanistically linked to PI3K signaling, modulation of adrenergic receptor expression, and normalization of immune cell function after hemorrhagic insult. Productized by APExBIO (SKU B5455), G-1 is established as a reference tool for GPR30 research across diverse experimental workflows.

    Biological Rationale

    Estrogens exert physiological effects through both classical nuclear receptors (ERα, ERβ) and membrane-bound G protein-coupled estrogen receptor GPR30 (GPER1). GPR30 is localized primarily to the endoplasmic reticulum membrane and mediates rapid, non-genomic signaling in multiple cell types (Wang et al. 2021). G-1, a synthetic, non-steroidal compound, was developed to probe GPR30-specific functions without confounding activation of ERα or ERβ (APExBIO). Selective activation of GPR30 enables the study of unique estrogenic effects on cardiovascular, immune, and oncogenic pathways. In preclinical studies, G-1 has been instrumental in distinguishing rapid, membrane-initiated estrogen responses from slower, genomic actions. This aligns with emerging interest in targeting GPR30 for disease modulation, particularly where rapid signaling confers therapeutic benefit.

    Mechanism of Action of G-1 (CAS 881639-98-1), a selective GPR30 agonist

    G-1 binds GPR30/GPER1 with high affinity (Ki ≈ 11 nM), inducing receptor-specific conformational changes (APExBIO). Upon activation, GPR30 initiates several intracellular signaling cascades:

    • Calcium Mobilization: G-1 triggers rapid elevation of intracellular Ca2+ in target cells (EC50 ≈ 2 nM, measured in SKBr3 breast cancer cells at 37°C, pH 7.4).
    • PI3K Activation: G-1 induces PI3K-dependent nuclear accumulation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3), a key step in growth and survival signaling.
    • Adrenergic Receptor Modulation: In vivo, chronic G-1 exposure normalizes β1-adrenergic receptor and upregulates β2-adrenergic receptor expression in heart tissue (Wang et al. 2021).

    Unlike estradiol and non-selective estrogen receptor agonists, G-1 exhibits negligible binding to ERα and ERβ at concentrations up to 1 µM, conferring high selectivity. This selectivity is crucial for attributing observed effects to GPR30 activation alone (Enhancing Cell Assay Reliability with G-1). This extends prior work by demonstrating functional isolation of GPR30-mediated pathways in complex biological systems.

    Evidence & Benchmarks

    • G-1 (CAS 881639-98-1) binds GPR30 with Ki ≈ 11 nM as determined by radioligand competition binding assays (APExBIO: product data).
    • G-1 does not activate ERα or ERβ in cell-based transcriptional assays at concentrations up to 1 µM, ensuring receptor specificity (Wang et al. 2021).
    • In SKBr3 and MCF7 breast cancer cells, G-1 inhibits cell migration with IC50 values of 0.7 nM and 1.6 nM, respectively, measured using Boyden chamber assays at 37°C, 5% CO2 (APExBIO).
    • In vivo, G-1 reduces brain natriuretic peptide (BNP) levels and cardiac fibrosis in ovariectomized female Sprague-Dawley rats with induced heart failure (chronic administration, 4 weeks, 10 mg/kg/day, i.p.) (Wang et al. 2021).
    • Beneficial effects on CD4+ T lymphocyte proliferation and immune normalization after hemorrhagic shock are abolished by G15 (GPR30 antagonist), confirming GPR30 specificity (Figure 1).
    • G-1 is soluble in DMSO at ≥41.2 mg/mL; insoluble in water and ethanol (APExBIO: product page).

    For a strategic overview of G-1 in translational research, see G-1 (CAS 881639-98-1): Strategic Empowerment of Translational Research, which this article updates by providing new quantitative benchmarks and clarifying receptor selectivity in vivo.

    Applications, Limits & Misconceptions

    G-1 (CAS 881639-98-1) is used in:

    • Cardiovascular Research: Dissecting rapid estrogenic protection against heart failure and fibrosis (Wang et al. 2021).
    • Oncology: Inhibiting migration and proliferation in breast cancer cell lines via GPR30 signaling (APExBIO).
    • Immunology: Normalizing immune responses after hemorrhagic shock by rescuing CD4+ T cell proliferation (Wang et al. 2021).
    • Cell Signaling Studies: Elucidating non-genomic estrogen pathways (see G-1: Advancing GPR30-Targeted Research in Immunity, Cardiology, Oncology; this article provides updated solubility and storage guidance for laboratory work).

    Common Pitfalls or Misconceptions

    • G-1 does not activate classical nuclear estrogen receptors (ERα, ERβ) at relevant concentrations—using it as a pan-estrogen mimetic is incorrect (Wang et al. 2021).
    • G-1 is insoluble in water and ethanol; attempts to dissolve in these solvents will fail or result in precipitation (APExBIO).
    • Long-term storage of G-1 solutions, even at -20°C, is not recommended; stability and potency may decline.
    • Observed effects in vivo require confirmation of GPR30 expression/function in the model—G-1 is not active in GPR30-null systems.
    • PI3K and calcium signaling activation by G-1 are context-dependent; not all cell types exhibit identical responses.

    Workflow Integration & Parameters

    For reliable experimental results, G-1 (CAS 881639-98-1) should be dissolved in DMSO at concentrations ≥10 mM. Gentle heating and ultrasonic bath aid solubility. Working solutions are best prepared fresh and stored at -20°C for short durations (APExBIO). DMSO concentration in cell assays should not exceed 0.1% (v/v) to avoid solvent toxicity. In vivo studies typically use daily intraperitoneal injections (e.g., 10 mg/kg in rats) for up to four weeks. For more detailed cell assay protocols and troubleshooting tips, see Enhancing Cell Assay Reliability with G-1, which this article supplements by providing updated solvent compatibility and batch-to-batch consistency insights.

    Use of validated GPR30 antagonists (e.g., G15) or genetic knockdown is recommended to confirm specificity in complex models. Negative controls (vehicle only) are essential for accurate data interpretation. For further workflow strategies and translational perspectives, Strategic Frontiers in GPR30 Activation offers a broader context, while this article focuses on atomic, quantitative benchmarks for laboratory planning.

    Conclusion & Outlook

    G-1 (CAS 881639-98-1), manufactured and quality-controlled by APExBIO (SKU B5455), remains the gold standard for selective GPR30 activation in preclinical research. Its nanomolar potency, selectivity, and robust in vivo efficacy enable precise mapping of rapid estrogenic signaling pathways. Continued integration of G-1 into cardiovascular, oncology, and immunological workflows is expected to accelerate discovery of GPR30-targeted therapeutics. Proper attention to solvent compatibility, storage, and specificity controls will maximize reproducibility and interpretability in future studies. For ordering or detailed specifications, visit the product page.