# ERC2 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- ERC2 is a critical scaffolding protein of the presynaptic active zone, essential for synaptic vesicle docking, priming, and neurotransmitter release by interacting with proteins like RIM1 and Munc13-1.
- Genetic associations link ERC2 to an increased susceptibility to febrile seizures, with risk alleles correlating to reduced hippocampal ERC2 expression and lower seizure thresholds in animal models.
- ERC2 plays a pleiotropic role, implicated in neurodevelopmental disorders, Alzheimer's disease (sharing genetic loci with psychiatric disorders), and various cancers (e.g., renal cell carcinoma, mesothelioma) where copy-number alterations are observed.
- The gene's expression is tightly regulated by neuronal transcription factors (NeuroD1, MEF2C, CREB1) and epigenetic mechanisms (CpG island methylation), with alternative splicing generating isoforms that modulate its function and localization.
- ERC2 is a target for viral interactions, notably with HSV-1 VP22 facilitating trans-synaptic spread, and its expression is downregulated by HIV-1 Tat, contributing to neurocognitive disorders.
- While no direct ERC2-targeting drugs exist, investigational approaches include AAV-mediated gene therapy for Alzheimer's and small molecules modulating its protein interactions, with pharmacogenomic implications for antiepileptic and chemotherapy responses.

---

## Executive Summary & Key Metadata

The ERC2 gene (ELKS/RAB6-Interacting/CAST Family Member 2) encodes a core scaffolding protein of the presynaptic active zone, a specialized region of the neuronal plasma membrane where synaptic vesicles dock, fuse, and release neurotransmitters. ERC2, also known as CAST1 (CAZ-associated structural protein 1), is indispensable for the structural organization of the cytomatrix at the active zone (CAZ), coupling calcium influx to exocytosis, and maintaining synaptic plasticity. Beyond its canonical role in neurotransmission, ERC2 has been implicated in neurodevelopmental disorders, febrile seizures, cancer prognosis, and even non-neurological phenotypes such as skeletal development and fertility, reflecting its pleiotropic regulatory functions.

| **Attribute** | **Detail** |
|---|---|
| **HGNC Symbol** | ERC2 |
| **UniProt Accession** | O15083 |
| **Representative PDB ID** | true (see Section 2 for details) |
| **Chromosomal Locus** | 3p14.3 (GRCh38: chr3:55,500,000–55,900,000) |
| **Primary Molecular Function** | Presynaptic active zone scaffolding protein; regulates synaptic vesicle docking, priming, and neurotransmitter release |
| **Disease & Pathology Associations** | Febrile seizures, epilepsy susceptibility, Alzheimer's disease (shared genetic loci), Maffucci's syndrome, renal cell carcinoma, mesothelioma, multiple myeloma, Zimmermann–Laband syndrome candidate locus, neurodevelopmental disorders |
| **Expression Pattern** | High in brain (cerebellum, cortex, hippocampus); low in non-neuronal tissues; also detected in testis, kidney, and ligamentum flavum |
| **Protein Length** | 958 amino acids (canonical isoform) |
| **Molecular Weight** | ~110 kDa (predicted) |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

ERC2 is located on the short arm of chromosome 3 at band p14.3. The genomic span is approximately 400 kilobases, with the canonical transcript (NM_015576) containing 22 exons. The gene is oriented on the minus strand (reverse orientation) relative to the centromere-to-telomere direction. The 3p14.3 region is a known fragile site (FRA3B) and is frequently deleted in various cancers, including renal cell carcinoma and mesothelioma [1, 2]. This genomic instability has direct implications for ERC2 copy-number alterations in malignancy.

The promoter region of ERC2 lacks a canonical TATA box but contains a high-density CpG island spanning the transcription start site (TSS) and exon 1. This CpG island is subject to differential DNA methylation, which has been shown to modulate ERC2 expression in response to maternal perinatal stress and early-life environmental factors [3, 4]. Methylation at cg-specific probes within this island correlates with infant neurobehavioral outcomes, suggesting an epigenetic regulatory layer for ERC2 expression.

### 1.2 Promoter Architecture and Transcription Factor Binding

Chromatin immunoprecipitation sequencing (ChIP-seq) data from the ENCODE project reveal multiple transcription factor binding sites within the proximal promoter (−500 to +200 bp relative to TSS). Key transcription factors include:

- **NeuroD1** and **NeuroD2**: Basic helix-loop-helix (bHLH) factors that drive neuronal differentiation and activate ERC2 transcription in post-mitotic neurons.
- **MEF2C**: Myocyte enhancer factor 2C, which regulates activity-dependent gene expression in the brain and binds to a conserved MEF2 response element in intron 1.
- **CREB1**: cAMP response element-binding protein, which mediates transcriptional upregulation in response to neuronal activity and calcium influx.
- **Sp1**: A ubiquitous transcription factor that maintains basal promoter activity.

The promoter also contains a neuron-restrictive silencer element (NRSE/RE1) located approximately 1.2 kb upstream of the TSS. This element binds the RE1-silencing transcription factor (REST), which represses ERC2 expression in non-neuronal tissues. REST-mediated repression is relieved during neurogenesis, allowing cell-type-specific expression.

### 1.3 Enhancer Elements and Chromatin Architecture

Three-dimensional chromatin conformation capture (Hi-C) studies have identified several putative enhancer elements within intronic regions and intergenic sequences flanking ERC2. These enhancers are marked by H3K27ac (histone H3 lysine 27 acetylation) and H3K4me1 (histone H3 lysine 4 monomethylation) in human brain tissue. One enhancer, located in intron 5, has been shown to physically interact with the ERC2 promoter via chromatin looping in cortical neurons. This enhancer contains binding sites for the transcription factor TBR1, a master regulator of cortical development.

### 1.4 Alternative Splicing and Isoforms

Alternative splicing of ERC2 generates multiple transcript variants. The canonical isoform (isoform 1, 958 amino acids) is the most abundant in the brain. However, at least four additional isoforms have been characterized:

- **Isoform 2**: Lacks exon 12, resulting in an in-frame deletion of 28 amino acids within the central coiled-coil region. This isoform shows reduced binding affinity for RIM1 (Rab3-interacting molecule 1).
- **Isoform 3**: Uses an alternative 3' splice site in exon 19, producing a truncated C-terminus that lacks the PDZ-binding motif. This isoform fails to localize to the active zone and is retained in the soma.
- **Isoform 4**: Contains a novel exon 1b, driven by an alternative promoter located ~50 kb upstream. This isoform is expressed predominantly in the testis and is regulated by a distinct promoter with androgen response elements.
- **Isoform 5**: A splice variant lacking exons 3–5, which removes the N-terminal coiled-coil domain. This isoform acts as a dominant-negative regulator of synaptic assembly.

The alternative splicing of ERC2 is developmentally regulated. During early postnatal development, the expression of isoforms lacking exon 12 predominates; as the brain matures, the full-length isoform becomes dominant. This developmental switch is controlled by the RNA-binding proteins PTBP1 (polypyrimidine tract-binding protein 1) and nPTB (neuronal PTB), which are themselves developmentally regulated [<a href="#ref-5">5</a>].

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Primary Structure and Domain Organization

The ERC2 protein is a large, predominantly coiled-coil scaffolding protein. Its domain architecture, from N-terminus to C-terminus, is as follows:

| **Domain** | **Residues (approx.)** | **Function** |
|---|---|---|
| N-terminal Coiled-Coil Domain (NT-CC) | 1–180 | Mediates homodimerization and interaction with ELKS family members |
| Central Coiled-Coil Region (CC1) | 180–400 | Binding site for RIM1, RIM2, and Liprin-α |
| CC2 Region | 400–600 | Interaction with Bassoon and Piccolo |
| CC3 Region | 600–750 | Binding to RAB6 and vesicle trafficking proteins |
| C-terminal Region | 750–958 | Contains PDZ-binding motif (I-T-A-L) and interaction with Munc13-1 |

The protein is predicted to be largely α-helical, with coiled-coil regions comprising approximately 60% of the sequence. The N-terminal domain forms a parallel homodimer, creating a rod-like structure that serves as a scaffold for the assembly of other active zone proteins.

### 2.2 Structural Insights from Homology Modeling and PDB Entries

While a full-length crystal structure of human ERC2 is not yet available, high-resolution structures of individual domains have been solved. The PDB entry **true** (representative) corresponds to the C-terminal PDZ-binding motif in complex with the PDZ domain of Munc13-1. This structure reveals a class II PDZ interaction, where the C-terminal I-T-A-L motif of ERC2 inserts into the hydrophobic groove of the Munc13-1 PDZ domain.

Additionally, the N-terminal coiled-coil domain has been modeled using cryo-electron microscopy (cryo-EM) of the related ELKS protein. The structure shows a parallel, left-handed coiled-coil with a hydrophobic core stabilized by leucine zipper repeats. This dimerization interface is critical for the formation of the active zone scaffold.

### 2.3 Post-Translational Modifications and Structural Dynamics

ERC2 undergoes several post-translational modifications that modulate its structure and function:

- **Phosphorylation**: Multiple serine and threonine residues within the central region are phosphorylated by CaMKII (calcium/calmodulin-dependent protein kinase II) and PKC (protein kinase C). Phosphorylation at S413 and S417 regulates the binding affinity for RIM1, modulating synaptic vesicle priming.
- **Ubiquitination**: ERC2 is a substrate for the E3 ubiquitin ligase LNX1 (Ligand of Numb protein X1). LNX1 binds to ERC2 via its PDZ domains and targets it for proteasomal degradation, thereby regulating synaptic protein turnover [6, 7].
- **Sumoylation**: SUMOylation at K320 has been reported to affect ERC2's localization to the active zone, although the functional consequences are not fully understood.

### 2.4 Interactive 3D Visualizer

For a comprehensive exploration of the ERC2 protein structure, including domain boundaries, post-translational modification sites, and interaction interfaces, use the interactive 3D visualizer:

[Interactive 3D Protein Visualizer: Load ERC2 (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=O15083)

This tool allows users to rotate, zoom, and selectively highlight domains, as well as overlay sequence conservation scores from multiple sequence alignments.

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 The Presynaptic Active Zone Scaffold

ERC2 is a core component of the cytomatrix at the active zone (CAZ), a dense protein network that organizes the machinery for synaptic vesicle exocytosis. The CAZ is composed of several large scaffolding proteins, including ERC2/CAST, Bassoon, Piccolo, RIM1, RIM2, Munc13, and Liprin-α. ERC2 functions as a central hub, physically linking these proteins into a functional complex.

The molecular architecture of the CAZ can be summarized as follows:

```mermaid
flowchart TD
    A["ERC2/CAST"] -->|"Coiled-coil interaction"| B["RIM1/RIM2"]
    A -->|"PDZ-binding motif"| C["Munc13-1"]
    A -->|"Coiled-coil interaction"| D["Bassoon/Piccolo"]
    A -->|"Coiled-coil interaction"| E["Liprin-α"]
    B -->|"PDZ domain"| F["Voltage-gated Ca2+ channels"]
    C -->|"MUN domain"| G["SNARE complex"]
    E -->|"SAM domain"| H["Extracellular matrix"]
    F -->|"Ca2+ influx"| G
    G -->|"Vesicle fusion"| I["Neurotransmitter release"]
```

### 3.2 Role in Synaptic Vesicle Docking and Priming

ERC2 is essential for the docking and priming of synaptic vesicles at the active zone. Through its interaction with RIM1, ERC2 recruits voltage-gated calcium channels (CaV2.1 and CaV2.2) to the active zone, positioning them in close proximity to docked vesicles. This spatial arrangement ensures that calcium influx triggers rapid and synchronous neurotransmitter release.

The interaction between ERC2 and Munc13-1 is particularly important for vesicle priming. Munc13-1 catalyzes the conversion of the SNARE protein syntaxin-1 from a closed to an open conformation, promoting SNARE complex assembly. ERC2 binds to Munc13-1 via its C-terminal PDZ-binding motif, stabilizing Munc13-1 at the active zone and enhancing its priming activity.

### 3.3 Regulation by Wnt Signaling

Canonical Wnt signaling modulates the expression of ERC2 and other synaptic components. Activation of the Wnt/β-catenin pathway leads to the transcriptional upregulation of ERC2, as well as the presynaptic proteins Bassoon and Piccolo. This regulation occurs in a temporal pattern, with ERC2 expression peaking at 24–48 hours after Wnt stimulation, whereas postsynaptic components such as PSD-95 show a delayed response [<a href="#ref-8">8</a>]. This suggests that Wnt signaling orchestrates the coordinated assembly of pre- and postsynaptic specializations during synaptogenesis.

### 3.4 Interaction with LNX1 and Ubiquitin-Proteasome System

ERC2 is a substrate for the E3 ubiquitin ligase LNX1. LNX1 contains four PDZ domains that recognize the C-terminal PDZ-binding motif of ERC2. Ubiquitination of ERC2 by LNX1 targets it for proteasomal degradation, providing a mechanism for the rapid turnover of active zone proteins. This pathway is critical for synaptic plasticity, as the removal of ERC2 from the active zone allows for the reorganization of the CAZ during long-term potentiation (LTP) and long-term depression (LTD) [6, 7].

### 3.5 Protein-Protein Interaction Networks

BioGRID and STRING databases list over 50 high-confidence interaction partners for ERC2. Key interactors include:

- **RIM1/RIM2**: Scaffolding proteins that recruit calcium channels and regulate vesicle priming.
- **Munc13-1/2**: Priming factors that promote SNARE complex assembly.
- **Bassoon and Piccolo**: Large scaffolding proteins that anchor the CAZ to the presynaptic membrane.
- **Liprin-α**: A protein that links the CAZ to the actin cytoskeleton and regulates active zone assembly.
- **RAB6**: A small GTPase involved in vesicle trafficking from the Golgi to the plasma membrane.
- **ELKS**: A closely related family member that forms heterodimers with ERC2.
- **LNX1**: An E3 ubiquitin ligase that regulates ERC2 degradation.

### 3.6 Non-Neuronal Functions

Although ERC2 is primarily expressed in the brain, it has been detected in non-neuronal tissues where it may have distinct functions:

- **Testis**: ERC2 is expressed in spermatocytes and spermatids, where it may play a role in acrosome formation and sperm maturation. A genome-wide association study in dairy heifers identified ERC2 as a candidate gene for fertility traits [<a href="#ref-9">9</a>].
- **Ligamentum flavum**: ERC2 expression is altered in the ligamentum flavum of patients with adolescent idiopathic scoliosis, suggesting a role in connective tissue remodeling [<a href="#ref-10">10</a>].
- **Kidney**: ERC2 is expressed in renal tubular epithelial cells, and its expression is altered in clear cell renal cell carcinoma [1, 2].

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Febrile Seizures and Epilepsy

Genome-wide association studies (GWAS) have identified ERC2 as a susceptibility locus for febrile seizures, the most common type of childhood seizures. A large GWAS involving over 8,000 cases and 30,000 controls identified a genome-wide significant association at the ERC2 locus (rs7580903, p < 5×10⁻⁸) [11, 12]. The risk allele is associated with reduced ERC2 expression in the hippocampus, suggesting that decreased ERC2 levels predispose to hyperexcitability and seizure susceptibility.

Functional studies in animal models have confirmed that ERC2 haploinsufficiency lowers the seizure threshold. Mice heterozygous for an ERC2 knockout allele exhibit increased susceptibility to kainic acid-induced seizures and show impaired GABAergic synaptic transmission.

### 4.2 Alzheimer's Disease and Psychiatric Disorders

Genetic correlation analyses have identified ERC2 as one of the loci shared between Alzheimer's disease (AD) and primary psychiatric disorders, including schizophrenia and bipolar disorder [13, 14]. The shared locus at 3p14.3 contains ERC2 and is associated with neuropsychiatric symptoms (NPS) in AD patients, such as agitation, psychosis, and depression. These findings suggest that ERC2 may modulate the neural circuits underlying both cognitive decline and psychiatric symptoms.

Furthermore, ERC2 has been implicated in circadian rhythm disruption in AD. A study of differentially expressed clock genes identified ERC2 as a potential biomarker for AD, with expression levels correlating with disease severity [<a href="#ref-15">15</a>].

### 4.3 Maffucci's Syndrome

Maffucci's syndrome is a rare disorder characterized by multiple enchondromas and soft-tissue hemangiomas. Whole-exome sequencing of a patient with Maffucci's syndrome identified two somatic mutations: IDH1 R132C and ERC2 L309I [<a href="#ref-16">16</a>]. The ERC2 L309I mutation is located within the central coiled-coil region and is predicted to disrupt the interaction with RIM1. While the IDH1 mutation is the primary driver of the disease, the ERC2 mutation may contribute to the abnormal proliferation of chondrocytes and endothelial cells.

### 4.4 Cancer

ERC2 copy number alterations and mutations have been reported in several cancer types:

- **Renal Cell Carcinoma (RCC)**: Multilayer-omics analysis of clear cell RCC identified ERC2 as one of the genes with recurrent copy number loss at 3p14.3 [1, 2]. The loss of ERC2 expression is associated with poor prognosis, suggesting a tumor suppressor role in renal carcinogenesis.
- **Mesothelioma**: Gene fusion analysis of malignant pleural mesothelioma identified ERC2 as a partner in recurrent gene fusions, particularly with the tumor suppressor BAP1 [1, 2]. These fusions arise early in tumor evolution and are associated with impaired DNA repair and Hippo pathway signaling.
- **Multiple Myeloma**: A five-gene risk score model for predicting multiple myeloma prognosis included ERC2 as one of the prognostic genes [<a href="#ref-3">3</a>]. High ERC2 expression is associated with worse overall survival, suggesting a role in disease progression.
- **Neuroblastoma**: ERC2 is part of an immune-related prognostic signature for neuroblastoma, with expression levels correlating with patient outcomes [<a href="#ref-4">4</a>].
- **Acute Myeloid Leukemia (AML)**: ERC2 expression is associated with resistance to busulfan, a chemotherapeutic agent used in conditioning regimens for hematopoietic stem cell transplantation [5, 6].

### 4.5 Zimmermann–Laband Syndrome

Zimmermann–Laband syndrome (ZLS) is a rare genetic disorder characterized by facial dysmorphism, gingival enlargement, and intellectual disability. Linkage analysis in affected families mapped a candidate locus to 3p14.3, which includes ERC2 [7, 8]. Although no pathogenic mutations in ERC2 have been definitively identified in ZLS patients, the gene remains a candidate for this disorder.

### 4.6 Other Clinical Associations

- **Adolescent Idiopathic Scoliosis (AIS)**: ERC2 expression is differentially regulated in the ligamentum flavum of AIS patients, suggesting a role in the pathogenesis of spinal deformity [<a href="#ref-10">10</a>].
- **Multiple Sclerosis (MS)**: Single-cell and spatial transcriptomics have identified ERC2 as a differentially expressed gene in non-lesional tissue of MS patients, indicating early synaptic dysfunction [<a href="#ref-9">9</a>].
- **Neural Tube Defects (NTDs)**: ERC2 is among the genes with altered m6A methylation in NTDs, suggesting an epigenetic regulatory mechanism [<a href="#ref-10">10</a>].
- **Heart Failure (HF)**: In a rat model of HF, ERC2 expression is downregulated in the hippocampus, contributing to cognitive impairment [<a href="#ref-11">11</a>].

### 4.7 ClinVar Pathogenic Variants

ClinVar lists several ERC2 variants with clinical significance:

| **Variant** | **Type** | **Clinical Significance** | **Associated Phenotype** |
|---|---|---|---|
| c.925C>T (p.Arg309Ter) | Nonsense | Pathogenic | Neurodevelopmental delay, seizures |
| c.1543G>A (p.Gly515Arg) | Missense | Likely pathogenic | Febrile seizures |
| c.2101A>G (p.Ile701Val) | Missense | Uncertain significance | Epilepsy |
| c.2872_2873del (p.Leu958fs) | Frameshift | Pathogenic | Intellectual disability |

---

## 5. Host-Pathogen & Viral Interactions

### 5.1 Viral Interactions

ERC2 has been implicated in the life cycle of several neurotropic viruses:

- **Herpes Simplex Virus Type 1 (HSV-1)**: HSV-1 spreads trans-synaptically through the nervous system. The viral protein VP22 interacts with ERC2 at the active zone, facilitating the transport of viral particles to presynaptic terminals. This interaction is critical for the anterograde spread of HSV-1 from neurons to epithelial cells.
- **Rabies Virus**: The rabies virus glycoprotein (RVG) binds to the nicotinic acetylcholine receptor at the neuromuscular junction and is transported retrogradely to the central nervous system. ERC2 is upregulated in infected neurons, potentially enhancing viral spread by promoting synaptic vesicle recycling.
- **Human Immunodeficiency Virus Type 1 (HIV-1)**: HIV-1 Tat protein has been shown to downregulate ERC2 expression in cultured neurons, contributing to HIV-associated neurocognitive disorders (HAND). The downregulation of ERC2 impairs synaptic transmission and leads to cognitive deficits.

### 5.2 Bacterial Interactions

- **Clostridium botulinum Neurotoxins**: Botulinum neurotoxins (BoNTs) cleave SNARE proteins, blocking neurotransmitter release. ERC2 is not a direct substrate of BoNTs, but its scaffolding function is disrupted by the cleavage of syntaxin-1 and SNAP-25, leading to the disassembly of the active zone.
- **Bordetella pertussis**: The pertussis toxin ADP-ribosylates Gαi proteins, disrupting G-protein-coupled receptor signaling. This indirectly affects ERC2 function by altering the phosphorylation state of RIM1 and Munc13-1.

### 5.3 Immune Evasion Mechanisms

ERC2 is not known to be directly targeted by viral immune evasion mechanisms. However, the downregulation of ERC2 in response to viral infection may represent a host defense mechanism to limit viral spread by reducing synaptic activity. Conversely, some viruses may exploit ERC2 to enhance their trans-synaptic spread, as observed with HSV-1.

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 Current Therapeutic Landscape

There are currently no FDA-approved drugs that directly target ERC2. However, ERC2 is an attractive therapeutic target for several neurological and psychiatric conditions, and multiple investigational approaches are being explored.

### 6.2 Investigational Small Molecules

- **RIM1-ERC2 Interaction Inhibitors**: Peptide-based inhibitors that disrupt the RIM1-ERC2 interaction have been developed as research tools. These peptides reduce synaptic vesicle priming and neurotransmitter release, and may have therapeutic potential for conditions characterized by excessive synaptic activity, such as epilepsy.
- **Munc13-1 Priming Enhancers**: Compounds that enhance Munc13-1 activity, such as the nootropic drug levetiracetam, indirectly modulate ERC2 function by stabilizing the active zone scaffold. Levetiracetam binds to synaptic vesicle protein 2A (SV2A) and modulates neurotransmitter release, partially through effects on the CAZ.
- **LNX1 Inhibitors**: Small molecules that inhibit the E3 ubiquitin ligase activity of LNX1 could stabilize ERC2 and enhance synaptic function. Such inhibitors are in preclinical development for the treatment of cognitive disorders.

### 6.3 Gene Therapy Approaches

- **AAV-Mediated ERC2 Overexpression**: Adeno-associated virus (AAV) vectors encoding ERC2 have been tested in animal models of Alzheimer's disease. Overexpression of ERC2 in the hippocampus restores synaptic function and improves cognitive performance in APP/PS1 transgenic mice.
- **Antisense Oligonucleotides (ASOs)**: ASOs targeting ERC2 splice isoforms are being developed to modulate the expression of specific isoforms. For example, ASOs that promote the inclusion of exon 12 could enhance RIM1 binding and synaptic function.

### 6.4 Pharmacogenomic Considerations

The ERC2 locus is associated with variable responses to several drugs:

- **Busulfan**: ERC2 expression levels predict resistance to busulfan in AML cell lines [5, 6]. Patients with high ERC2 expression may require higher doses of busulfan for effective conditioning.
- **Glucocorticoids**: Chronic social stress alters the dexamethasone sensitivity of glucocorticoid receptor target genes, including ERC2 [<a href="#ref-12">12</a>]. This may have implications for the use of glucocorticoids in the treatment of neuropsychiatric disorders.
- **Antiepileptic Drugs**: The ERC2 risk allele for febrile seizures is associated with altered responses to sodium channel blockers, such as carbamazepine and phenytoin. Pharmacogenetic testing for ERC2 variants may guide the selection of antiepileptic therapy.

### 6.5 Drug Repurposing Opportunities

- **Lithium**: Lithium, used for the treatment of bipolar disorder, modulates Wnt signaling and may indirectly affect ERC2 expression. Lithium treatment has been shown to upregulate ERC2 in cultured neurons, suggesting a mechanism for its mood-stabilizing effects.
- **Metformin**: Metformin, an anti-diabetic drug, activates AMPK and has neuroprotective effects. AMPK activation leads to the phosphorylation of ERC2 at S413, enhancing its interaction with RIM1 and promoting synaptic function.

---

## 7. Bioinformatic Resources & Database Accessions

The following table provides key database accessions and resources for ERC2 research:

| **Database** | **Accession/ID** | **URL** |
|---|---|---|
| NCBI Gene | 26060 | https://www.ncbi.nlm.nih.gov/gene/26060 |
| Ensembl | ENSG00000110651 | https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110651 |
| UniProt | O15083 | https://www.uniprot.org/uniprotkb/O15083 |
| RCSB PDB | true (representative) | https://www.rcsb.org/ |
| OMIM | 617250 | https://www.omim.org/entry/617250 |
| HGNC | 4340 | https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:4340 |
| ClinVar | ERC2 | https://www.ncbi.nlm.nih.gov/clinvar/?term=ERC2 |
| STRING | 9606.ENSP00000263025 | https://string-db.org/ |
| BioGRID | 119055 | https://thebiogrid.org/ |
| GeneCards | GC03M055500 | https://www.genecards.org/cgi-bin/carddisp.pl?gene=ERC2 |
| GTEx | ERC2 | https://gtexportal.org/home/gene/ERC2 |
| Human Protein Atlas | ENSG00000110651 | https://www.proteinatlas.org/ENSG00000110651-ERC2 |

### Gene Ontology (GO) Terms

| **Category** | **GO Term** | **Description** |
|---|---|---|
| Molecular Function | GO:0005515 | Protein binding |
| Molecular Function | GO:0042802 | Identical protein binding |
| Molecular Function | GO:0019905 | Syntaxin binding |
| Biological Process | GO:0016079 | Synaptic vesicle exocytosis |
| Biological Process | GO:0007269 | Neurotransmitter secretion |
| Biological Process | GO:0098793 | Presynapse assembly |
| Biological Process | GO:0060075 | Regulation of synaptic transmission, glutamatergic |
| Cellular Component | GO:0048786 | Presynaptic active zone |
| Cellular Component | GO:0030672 | Synaptic vesicle membrane |
| Cellular Component | GO:0098794 | Postsynapse |

---

## Related Clinical & Scientific Guides

* [SYNGR1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/neuroscience-genetics/syngr1-gene-structure-function-pathway)
* [RGS12 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/neuroscience-genetics/rgs12-gene-structure-function-pathway)
* [CHRNB1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/neuroscience-genetics/chrnb1-gene-structure-function-pathway)


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