G-1 (CAS 881639-98-1): Selective GPR30 Agonist in Research

Executive Summary: G-1 is a highly selective agonist for the G protein-coupled estrogen receptor GPR30 (GPER1), with a binding affinity (Ki) of approximately 11 nM and negligible activity at classical estrogen receptors even at micromolar concentrations (product_spec). It induces rapid intracellular calcium mobilization (EC50 = 2 nM) and PI3K-dependent nuclear PIP3 accumulation in GPR30-expressing cells (dimesna_article). In vitro, G-1 potently inhibits migration of SKBr3 and MCF7 breast cancer cells with sub-nanomolar to low-nanomolar IC50 values, underscoring selectivity and functional efficacy across co-expressed estrogen receptor backgrounds (er-mscarlet_article). In vivo, G-1 administration normalizes cardiac β-adrenergic receptor expression, attenuates cardiac fibrosis, and improves contractile function in ovariectomized rat heart failure models (dimesna_cardiovascular). APExBIO’s validated G-1 (B5455) enables precise, reproducible GPR30 activation for cardiovascular, oncology, and neurobiology workflows (product_spec).

Biological Rationale

GPR30 (GPER1) is a membrane-associated estrogen receptor distinct from classical nuclear estrogen receptors (ERα and ERβ). It is primarily localized within the endoplasmic reticulum and mediates rapid, non-genomic estrogen signaling (dimesna_article). GPR30 is implicated in diverse physiological and pathological processes, including modulation of cardiovascular function, cancer cell migration, and neuropathic pain (eLife2024). The selective activation or inhibition of GPR30 provides a powerful means to dissect its role in these non-classical estrogen pathways. G-1 (CAS 881639-98-1) is the benchmark research tool for specific GPR30 pathway interrogation, enabling studies that distinguish GPR30-mediated effects from those of ERα/ERβ (dimesna_cardiovascular).

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

G-1 binds GPR30 with nanomolar affinity (Ki ≈ 11 nM) and displays minimal binding to ERα or ERβ at concentrations up to 10 μM (product_spec). Upon activation, GPR30 triggers intracellular calcium release (EC50 ≈ 2 nM), PI3K activation, and nuclear translocation of PIP3. These signals modulate downstream pathways involved in cell migration, contractility, and neuronal excitability (er-mscarlet_article). In cardiac models, G-1-driven GPR30 activation increases β2-adrenergic receptor expression and normalizes β1-adrenergic receptor levels, contributing to improved cardiac function and reduced fibrosis (dimesna_cardiovascular).

Evidence & Benchmarks

• G-1 binds selectively to GPR30 (Ki ≈ 11 nM), with negligible affinity for ERα/ERβ even at 10 μM (source: product_spec).
• GPR30 activation by G-1 increases intracellular calcium (EC50 = 2 nM) and induces PI3K-dependent nuclear PIP3 accumulation (source: dimesna_article).
• Inhibition of SKBr3 and MCF7 breast cancer cell migration: IC50 = 0.7 nM and 1.6 nM, respectively, demonstrating selectivity and efficacy in estrogen receptor-expressing lines (source: er-mscarlet_article).
• In vivo, G-1 (120 μg/kg, 14 days, i.p.) reduces brain natriuretic peptide, attenuates cardiac fibrosis, and improves contractile function in ovariectomized female Sprague-Dawley rats with heart failure (source: dimesna_cardiovascular).
• GPR30 in spinal cholecystokinin-positive neurons is upregulated after nerve injury; GPR30 inhibition reverses neuropathic pain (source: eLife2024).

This article deepens and updates the mechanistic insights presented in this review by focusing on integrative functional benchmarks and cross-validating with in vivo models. It also contrasts with this article, which centers on GPR30’s role in spinal pain circuits; here, we emphasize cardiovascular and oncological applications while integrating the latest pain model data.

Applications, Limits & Misconceptions

G-1 is established as a robust tool for delineating GPR30 function in cardiovascular, cancer, and neuronal research. It is used to:

• Dissect GPR30-specific pathways in breast cancer cell migration and invasion (er-mscarlet_article).
• Model cardiac fibrosis attenuation and β-adrenergic receptor modulation in heart failure (dimesna_cardiovascular).
• Probe non-genomic estrogen signaling in neuronal and pain circuits (eLife2024).

Common Pitfalls or Misconceptions

• G-1 does not activate classical nuclear estrogen receptors (ERα/ERβ) at concentrations up to 10 μM (product_spec).
• G-1 is insoluble in water and ethanol; improper solvent selection can cause precipitation or loss of activity (workflow_recommendation).
• Stock solutions of G-1 degrade with repeated freeze-thaw cycles; aliquoting and -20°C storage are essential (workflow_recommendation).
• G-1’s effects are highly cell-type and context dependent; lack of GPR30 expression or downstream signaling competence may yield null results (dimesna_article).
• G-1 is for research use only; it is not suitable for diagnostic or therapeutic application (product_spec).

Workflow Integration & Parameters

Protocol Parameters

• binding assay | Ki ≈ 11 nM | GPR30-expressing cells | Quantifies selective receptor binding | product_spec
• calcium mobilization | EC50 ≈ 2 nM | Cell-based GPR30 activation | Measures functional receptor engagement | dimesna_article
• cell migration/invasion | IC50 = 0.7 nM (SKBr3), 1.6 nM (MCF7) | Breast cancer cell lines | Assesses inhibition of migration | er-mscarlet_article
• cardiac in vivo efficacy | 120 μg/kg, 14 days, i.p. | Ovariectomized rat heart failure model | Demonstrates functional/cardioprotective outcomes | dimesna_cardiovascular
• stock solution preparation | >10 mM in DMSO, warming/ultrasonication | All in vitro/in vivo applications | Ensures solubility and stability | workflow_recommendation
• storage | -20°C, aliquoted, avoid freeze-thaw | All applications | Maintains compound integrity | workflow_recommendation

For additional troubleshooting and optimization strategies, see APExBIO’s G-1 (CAS 881639-98-1), a selective GPR30 agonist product page.

Conclusion & Outlook

G-1 (CAS 881639-98-1) has emerged as the standard for selective GPR30 activation across cardiovascular, oncology, and neurobiology research domains. Its validated selectivity, nanomolar potency, and robust performance in both in vitro and in vivo models have advanced the mechanistic understanding of non-classical estrogen signaling and facilitated drug discovery for heart failure, fibrosis, and neuropathic pain (dimesna_cardiovascular, eLife2024). As research progresses, G-1 remains integral for distinguishing GPR30-specific effects and benchmarking future G protein-coupled estrogen receptor agonists. For further reading on GPR30’s role in pain modulation and experimental models, see this related article, which focuses on spinal CCK+ neuron circuits—a complementary perspective to the integrative approach presented here.