GO:0002115 store-operated calcium entry: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0002115 store-operated calcium entry (SOCE) is a plasma membrane calcium entry mechanism activated by depletion of endoplasmic reticulum calcium stores.
• The core molecular players are the ER calcium sensor STIM1 and the plasma membrane calcium channel ORAI1, which together form the canonical SOCE pathway.
• SOCE is essential for diverse physiological processes including immune cell activation, skeletal muscle function, cell migration, and cardiovascular homeostasis.
• Dysregulated SOCE contributes to cancer progression, cancer stem cell maintenance, tubular aggregate myopathy, and cardiovascular disease.
• SOCE can be studied using calcium imaging, patch-clamp electrophysiology, genetically encoded calcium indicators, and CRISPR-based gene editing.
• CRISPR knockout, point mutation, knock-in, and overexpression models enable causal dissection of STIM1, ORAI1, and related SOCE genes in disease contexts.
Description
Store-operated calcium entry (SOCE), encoded by the Gene Ontology term GO:0002115, is a fundamental calcium ion entry mechanism in the plasma membrane that is activated when calcium is depleted from the endoplasmic reticulum (ER) store. This process, also known as capacitative calcium entry, allows cells to refill their ER calcium stores and sustain prolonged calcium signaling essential for numerous cellular functions. The discovery of the ER calcium sensor STIM1 and the plasma membrane channel ORAI1 established the molecular basis of SOCE and transformed our understanding of calcium homeostasis. SOCE is now recognized as a central regulator of immune responses, muscle contraction, cell migration, proliferation, and gene expression. In immune cells, SOCE is required for T cell activation and cytokine production, while in skeletal muscle it supports sustained calcium signals needed for fatigue resistance and muscle maintenance. In the cardiovascular system, SOCE modulates vascular tone, cardiac hypertrophy, and endothelial function. Beyond physiology, dysregulated SOCE has been implicated in cancer stem cell maintenance, tumor metastasis, and chemoresistance, making it an attractive therapeutic target. This article provides a research-grade overview of SOCE, covering its definition, molecular mechanism, key genes, disease relevance, and experimental methods for studying this pathway.
store-operated calcium entry At A Glance
| GO ID | GO:0002115 |
|---|---|
| GO term | store-operated calcium entry |
| Ontology | biological_process |
| Synonym | calcium ion import, capacitative calcium entry, SOCE, store-operated calcium import |
| Major function | Calcium ion entry across the plasma membrane activated by depletion of endoplasmic reticulum calcium stores |
| Key molecular players | STIM1 (ER calcium sensor), ORAI1 (plasma membrane calcium channel) |
| Physiological contexts | Immune cell activation, skeletal muscle function, cardiovascular homeostasis, cell migration |
| Disease relevance | Cancer, tubular aggregate myopathy, cardiovascular disease, immunodeficiency |
What Is GO:0002115?
According to the Gene Ontology, GO:0002115 store-operated calcium entry is defined as a calcium ion entry mechanism in the plasma membrane activated by the depletion of calcium ion from the internal calcium ion store in the endoplasmic reticulum. In simpler terms, when the ER runs low on calcium, specialized proteins in the plasma membrane open to let calcium in from outside the cell, thereby replenishing the ER store and sustaining calcium-dependent signaling.
Why Is store-operated calcium entry Important in Cell Biology?
SOCE is critically important because it serves as the primary mechanism for replenishing ER calcium stores and sustaining calcium signals that control gene expression, cell proliferation, migration, and immune responses. Defects in SOCE components cause severe human diseases, including tubular aggregate myopathy and immunodeficiency, while enhanced SOCE contributes to cancer progression and metastasis. Understanding SOCE is therefore essential for both basic cell biology and therapeutic development.
• SOCE is the main pathway for refilling ER calcium stores after depletion, enabling sustained calcium signaling.
• STIM1 and ORAI1 mutations cause tubular aggregate myopathy and related muscle disorders.
• SOCE is required for T cell activation, cytokine production, and immune surveillance.
• In skeletal muscle, SOCE supports calcium homeostasis and fatigue resistance.
• SOCE regulates vascular tone, cardiac hypertrophy, and endothelial function in the cardiovascular system.
• Enhanced SOCE promotes cancer cell migration, metastasis, and cancer stem cell maintenance.
• SOCE is a target for novel cancer therapeutics, including inhibitors of STIM1 and ORAI1.
• SOCE modulates cell migration and metastasis in multiple cancer types.
• SOCE dysfunction is linked to cardiovascular diseases such as hypertension and heart failure.
• SOCE can be studied with CRISPR-based models to dissect gene function in disease.
What Happens During store-operated calcium entry?
ER calcium depletion and STIM1 activation
In simple terms: When the ER runs out of calcium, a sensor protein called STIM1 detects this and gets ready to open calcium channels.
The initiation of SOCE requires depletion of calcium from the endoplasmic reticulum (ER) lumen. STIM1, an ER-resident transmembrane protein, senses luminal calcium through its EF-hand domain. Upon calcium depletion, STIM1 undergoes conformational changes, oligomerizes, and translocates to ER-plasma membrane junctions. This activation step is the primary trigger for store-operated calcium entry and is conserved across cell types.
STIM1-ORAI1 coupling and channel opening
In simple terms: The activated sensor protein STIM1 physically reaches out and opens ORAI1 calcium channels in the cell membrane.
Activated STIM1 oligomers accumulate at ER-plasma membrane junctions where they directly bind to the C-terminus of ORAI1 channels. This interaction triggers conformational changes in ORAI1 that open the channel pore, allowing calcium ions to flow into the cytosol from the extracellular space. The STIM1-ORAI1 coupling is the central molecular event of SOCE and is tightly regulated to prevent excessive calcium entry.
Calcium influx and ER store refilling
In simple terms: Calcium flows into the cell and is pumped back into the ER to refill the store.
Once ORAI1 channels open, calcium enters the cytosol down its concentration gradient. This calcium influx serves two purposes: it sustains cytosolic calcium signals for downstream effectors such as calcineurin and NFAT, and it provides calcium for refilling the ER store via sarco/endoplasmic reticulum calcium ATPases (SERCAs). The balance between calcium entry and extrusion determines the duration and amplitude of SOCE-dependent signaling.
Termination and feedback regulation
In simple terms: When the ER store is refilled, the sensor turns off the channels to stop calcium entry.
As the ER calcium store is refilled, STIM1 gradually dissociates from ORAI1, leading to channel closure and termination of SOCE. This feedback regulation prevents calcium overload and is modulated by calcium-dependent inactivation mechanisms involving calmodulin and other regulatory proteins. Dysregulation of SOCE termination can contribute to pathological calcium signaling in disease.
Key Genes Involved in GO:0002115 store-operated calcium entry
The following genes encode the core molecular components and regulators of store-operated calcium entry, as established in the literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| STIM1 | ER calcium sensor that activates ORAI1 upon store depletion | Central to SOCE; mutations cause tubular aggregate myopathy |
| ORAI1 | Plasma membrane calcium channel mediating SOCE | Mutations cause immunodeficiency; target for cancer therapy |
| ORAI2 | Calcium channel that can form heteromers with ORAI1 | Modulates SOCE amplitude and kinetics in various cell types |
| ORAI3 | Calcium channel contributing to SOCE in some tissues | Tissue-specific SOCE regulation |
| STIM2 | ER calcium sensor with lower calcium affinity than STIM1 | Regulates basal calcium and neuronal SOCE |
| TRPC1 | Transient receptor potential channel contributing to SOCE | Modulates SOCE in smooth muscle and cancer cells |
| TRPC3 | TRP channel involved in SOCE-like calcium entry | Cardiovascular and neuronal calcium signaling |
| TRPC6 | TRP channel implicated in SOCE and cardiac hypertrophy | Cardiovascular disease models |
| CALM1 | Calmodulin regulating ORAI1 inactivation | Feedback control of SOCE |
| CALM2 | Calmodulin isoform involved in calcium-dependent inactivation | SOCE termination |
| CALM3 | Calmodulin isoform modulating SOCE | Calcium signaling regulation |
| SERCA1 (ATP2A1) | Pumps calcium back into ER to refill stores | ER store refilling and muscle function |
| SERCA2 (ATP2A2) | ER calcium pump essential for store refilling | Cardiovascular and muscle SOCE |
| CRACR2A | Regulates STIM1-ORAI1 interaction | Modulates SOCE in immune cells |
| SARAF | Negative regulator of SOCE by promoting STIM1 inactivation | Prevents calcium overload |
| Septin4 | Scaffold protein regulating STIM1-ORAI1 coupling | SOCE modulation in various tissues |
| EB1 | Microtubule plus-end tracking protein involved in STIM1 translocation | Cytoskeletal regulation of SOCE |
How Is store-operated calcium entry Regulated?
SOCE is regulated at multiple levels to ensure appropriate calcium entry. STIM1 activation is controlled by ER luminal calcium concentration through its EF-hand domain, and its translocation to ER-plasma membrane junctions is modulated by microtubules and scaffolding proteins such as EB1 and Septin4. ORAI1 channel activity is subject to calcium-dependent inactivation mediated by calmodulin and SARAF, which prevent excessive calcium influx. Additionally, SOCE is modulated by phosphorylation, redox status, and interactions with other calcium channels such as TRPC proteins. In disease contexts, altered expression levels of STIM and ORAI proteins, as well as mutations affecting their function, can dysregulate SOCE beyond simple expression changes.
store-operated calcium entry and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| STIM1 | Tubular aggregate myopathy; cancer progression | Knock-in of gain-of-function mutation in muscle cells |
| ORAI1 | Immunodeficiency; cancer | Knockout in T cells or cancer cell lines |
| TRPC6 | Cardiac hypertrophy | Overexpression in cardiomyocytes |
| STIM2 | Neurodegeneration; calcium dyshomeostasis | Knockout in neuronal cells |
| ORAI3 | Cancer cell migration | Knockdown in metastatic cancer cells |
SOCE in cancer and cancer stem cells
Store-operated calcium entry is increasingly recognized as a driver of cancer progression. SOCE components, particularly STIM1 and ORAI1, are upregulated in various cancers and contribute to cancer stem cell maintenance, proliferation, migration, and metastasis. Enhanced SOCE supports the calcium signaling required for cancer stem cell self-renewal and resistance to therapy, making SOCE an attractive target for novel cancer therapeutics. Targeting SOCE with pharmacological inhibitors or genetic tools has shown promise in reducing tumor growth and metastasis in preclinical models.
SOCE in tubular aggregate myopathy and muscle disorders
Mutations in STIM1 and ORAI1 that lead to constitutively active SOCE cause tubular aggregate myopathy, a rare muscle disorder characterized by muscle weakness and the presence of tubular aggregates in muscle fibers. These gain-of-function mutations highlight the importance of tight SOCE regulation in skeletal muscle physiology. In skeletal muscle, SOCE differs from other tissues due to the presence of specialized calcium handling proteins and the unique architecture of the sarcoplasmic reticulum, making it a distinct area of research.
SOCE in cardiovascular disease
SOCE plays critical roles in the cardiovascular system, where it regulates vascular smooth muscle tone, cardiac hypertrophy, and endothelial function. Dysregulated SOCE contributes to hypertension, atherosclerosis, and heart failure. In cardiac hypertrophy, increased SOCE and TRPC channel activity promote pathological remodeling, and inhibition of SOCE has been proposed as a therapeutic strategy.
SOCE in immune disorders
Loss-of-function mutations in ORAI1 or STIM1 cause severe combined immunodeficiency due to defective T cell activation and cytokine production. SOCE is essential for the immune response, and its dysregulation can lead to autoimmunity or immunodeficiency. Understanding SOCE in immune cells has provided critical insights into the molecular basis of calcium signaling in health and disease.
From store-operated calcium entry-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does STIM1 loss abolish SOCE? | STIM1 knockout cells (e.g., HEK293, T cells) |
| Do gain-of-function STIM1 mutations cause myopathy? | STIM1 knock-in mice or patient-derived cells |
| Can ORAI1 point mutations alter channel gating? | ORAI1 point-mutant knock-in cell lines |
| Does overexpression of ORAI1 enhance cancer metastasis? | ORAI1 overexpression in cancer cell lines |
| How does STIM2 regulate neuronal SOCE? | STIM2 knockout neurons |
| Can CRISPR screen identify novel SOCE regulators? | Genome-wide CRISPR knockout library in calcium reporter cells |
How to Study the store-operated calcium entry Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Calcium imaging (Fura-2, Fluo-4) | Cytosolic calcium concentration changes | Measuring SOCE in live cells |
| Genetically encoded calcium indicators (GCaMP) | Compartment-specific calcium dynamics | Real-time SOCE monitoring in specific organelles |
| Patch-clamp electrophysiology | CRAC channel currents | Biophysical characterization of ORAI1 |
| CRISPR knockout screens | Gene essentiality for SOCE | Identifying novel SOCE regulators |
| Proximity labeling (BioID, APEX) | Protein-protein interactions | Mapping STIM1-ORAI1 interactome |
| Phosphoproteomics | Phosphorylation changes downstream of SOCE | Signaling pathway analysis |
| RNA-seq | Transcriptional changes upon SOCE modulation | Gene expression profiling in SOCE-related diseases |
| Immunofluorescence | Subcellular localization of STIM1/ORAI1 | ER-plasma membrane junction formation |
Calcium imaging and genetically encoded indicators
Calcium imaging using fluorescent dyes (e.g., Fura-2, Fluo-4) or genetically encoded calcium indicators (GECIs) such as GCaMP is the primary method to measure SOCE in live cells. These techniques allow real-time monitoring of cytosolic calcium changes following ER store depletion with thapsigargin or ionomycin. GECIs can be targeted to specific cellular compartments to study SOCE dynamics with high spatial and temporal resolution.
Patch-clamp electrophysiology
Patch-clamp recording of calcium release-activated calcium (CRAC) currents is the gold standard for measuring ORAI1 channel activity directly. This method provides precise biophysical characterization of SOCE, including current-voltage relationships, activation kinetics, and calcium-dependent inactivation. It is particularly useful for studying point mutations in ORAI1 that alter channel gating.
CRISPR-based genetic screens
Genome-wide CRISPR knockout or activation screens combined with calcium reporters enable unbiased identification of novel SOCE regulators. These screens can reveal genes that modulate SOCE in cancer cells or immune cells, providing new therapeutic targets. Bioinformatics analysis of screen hits can uncover pathways and networks connected to SOCE.
Proteomics and interactomics
Proteomic approaches such as immunoprecipitation-mass spectrometry (IP-MS) and proximity labeling can identify proteins that interact with STIM1 and ORAI1. These methods help define the SOCE interactome and reveal regulatory mechanisms. Phosphoproteomics can uncover signaling events downstream of SOCE.
How CRISPR Can Be Used to Study GO:0002115 store-operated calcium entry
Knockout
CRISPR knockout of STIM1 or ORAI1 completely abolishes SOCE, providing a clean genetic model to study the pathway's role in cell physiology and disease. Knockout cell lines are valuable for dissecting the contribution of SOCE to processes such as T cell activation, cancer cell migration, and muscle function. Genome-wide knockout screens can identify additional genes required for SOCE.
Point Mutation
CRISPR-mediated point mutations can recreate disease-associated mutations in STIM1 or ORAI1, such as gain-of-function mutations causing tubular aggregate myopathy. These models allow precise interrogation of how specific amino acid changes alter channel gating, calcium sensing, or protein interactions. Point mutation knock-in cell lines are essential for testing targeted therapies.
Knock-in
Knock-in of tagged versions of STIM1 or ORAI1 (e.g., GFP, HA) enables live-cell imaging and biochemical analysis of SOCE components at endogenous expression levels. Knock-in of patient-specific mutations into cell lines or animal models provides physiologically relevant disease models. CRISPR knock-in can also be used to introduce reporters for high-throughput screening.
Overexpression
Overexpression of STIM1, ORAI1, or TRPC channels in cell lines enhances SOCE and can model pathological states such as cancer or cardiac hypertrophy. Overexpression systems are useful for studying the effects of increased SOCE on cell proliferation, migration, and survival. However, results should be interpreted with caution due to potential non-physiological expression levels.
How EDITGENE Supports store-operated calcium entry Research
Researchers studying store-operated calcium entry-related genes often need to determine whether a candidate gene is causally involved in SOCE regulation or disease pathogenesis. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models, enabling functional validation of SOCE components in relevant biological contexts.
Contact EDITGENE today to design your custom CRISPR model for store-operated calcium entry research.
Frequently Asked Questions About store-operated calcium entry
What is store-operated calcium entry (SOCE)?
Store-operated calcium entry (SOCE) is a calcium ion entry mechanism in the plasma membrane activated by depletion of calcium from the endoplasmic reticulum store. It is encoded by GO:0002115 and is also known as capacitative calcium entry.
What genes are involved in store-operated calcium entry?
The core genes are STIM1 (ER calcium sensor) and ORAI1 (plasma membrane calcium channel). Other genes include ORAI2, ORAI3, STIM2, TRPC1, TRPC3, TRPC6, and regulatory proteins such as CRACR2A and SARAF.
What is the role of STIM1 in SOCE?
STIM1 is an endoplasmic reticulum calcium sensor that detects store depletion and activates ORAI1 channels at ER-plasma membrane junctions, initiating calcium influx.
What is the role of ORAI1 in SOCE?
ORAI1 is the pore-forming subunit of the calcium release-activated calcium (CRAC) channel in the plasma membrane. It opens upon STIM1 binding to allow calcium entry.
How is store-operated calcium entry measured?
SOCE is measured using calcium imaging with fluorescent dyes or genetically encoded indicators, patch-clamp electrophysiology for CRAC currents, and CRISPR-based screens for genetic dissection.
What diseases are associated with store-operated calcium entry?
SOCE is linked to cancer, tubular aggregate myopathy, cardiovascular disease, and immunodeficiency. Mutations in STIM1 and ORAI1 cause myopathy and immune disorders, while enhanced SOCE promotes cancer progression.
Can CRISPR be used to study SOCE?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect SOCE gene function and model disease-associated mutations.
What is the difference between SOCE and CRAC channels?
SOCE is the broader process of store-operated calcium entry, while CRAC (calcium release-activated calcium) channels are the specific channels (composed of ORAI proteins) that mediate SOCE.
How does SOCE contribute to cancer?
SOCE supports cancer stem cell maintenance, proliferation, migration, and metastasis by sustaining calcium signaling. Targeting SOCE components is a promising therapeutic strategy.
What are the key regulators of SOCE?
Key regulators include STIM1, ORAI1, calmodulin, SARAF, CRACR2A, Septin4, and EB1, which control activation, inactivation, and trafficking of SOCE components.
Conclusion
Store-operated calcium entry (GO:0002115) is a fundamental calcium signaling mechanism that connects endoplasmic reticulum calcium store depletion to plasma membrane calcium influx. The STIM1-ORAI1 axis is the core molecular machinery, and its dysregulation underlies diverse human diseases including cancer, myopathies, cardiovascular disorders, and immunodeficiency. Advances in CRISPR-based gene editing, calcium imaging, and high-throughput screening continue to unravel the complexities of SOCE regulation and its therapeutic potential. Targeting SOCE components offers promising avenues for drug development, particularly in cancer and muscle disorders, and ongoing research will further define the precise roles of SOCE in health and disease.
References
- 1. Jardin I et al.. 2022. Store-Operated Calcium Entry and Its Implications in Cancer Stem Cells.. Cells 11(8) PMID: 35456011
- 2. Hala'ufia ME et al.. 2025. Store-operated calcium entry-based targets for novel cancer therapeutic development.. J Pharmacol Exp Ther 392(10):103682 PMID: 41033085
- 3. Liu X et al.. 2021. Store-Operated Calcium Entry in the Cardiovascular System.. Adv Exp Med Biol 1349:303-333 PMID: 35138620
- 4. Lilliu E et al.. 2021. Store-Operated Calcium Entry in Skeletal Muscle: What Makes It Different?. Cells 10(9) PMID: 34572005
- 5. Hammad AS et al.. 2021. Store Operated Calcium Entry in Cell Migration and Cancer Metastasis.. Cells 10(5) PMID: 34069353
- 6. Protasi F et al.. 2023. Store-operated calcium entry: From physiology to tubular aggregate myopathy.. Curr Opin Pharmacol 68:102347 PMID: 36608411
- 7. Kappel S et al.. 2019. Store-operated calcium entry in disease: Beyond STIM/Orai expression levels.. Semin Cell Dev Biol 94:66-73 PMID: 30630032
- 8. Hogan PG et al.. 2015. Store-operated calcium entry: Mechanisms and modulation.. Biochem Biophys Res Commun 460(1):40-9 PMID: 25998732
