The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
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We are interested in where in or outside the cell the gene product carries out its function.
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ERC1 (also called ELKS, RAB6IP2; UniProt Q8IUD2) is a large coiled-coil–rich scaffold protein that organizes membrane-proximal secretion and synaptic release sites by forming higher-order assemblies (“platforms/condensates”) that capture Rab6-positive secretory carriers and recruit active-zone/cortical factors that specify vesicle docking and fusion locations. Mechanistic advances in 2023–2024 include a high-resolution structural model of its Rab6B-binding domain and growing evidence that liquid–liquid phase separation (LLPS) enhances vesicle capture and scaffold function. (ashraf2025prevalenceandfunctional pages 29-31, jin2023structuralbasisof pages 1-2, jin2023structuralbasisof pages 2-5)
| Aspect | Key details | Evidence (citations) |
|---|---|---|
| Verified identity (human) | ERC1 (ELKS/Rab6-interacting/CAST family member 1); UniProt Q8IUD2; synonyms: ELKS, RAB6IP2, CAST2; organism: Homo sapiens | (ashraf2025prevalenceandfunctional pages 29-31, ashraf2025prevalenceandfunctional pages 27-29, hida2010castandelks pages 2-3) |
| Key domains/regions | N-terminal intrinsically disordered region (IDR); long central coiled-coils; C-terminal Rab6-binding domain (RBD) mapped to residues 849–922; C-terminal PDZ-binding/IWA motif (RIM PDZ interaction) | (jin2023structuralbasisof pages 2-5, jin2023structuralbasisof pages 1-2, hida2010castandelks pages 2-3) |
| Experimentally-mapped interaction regions | Direct ERC1–LL5β binding: ERC1(270–370) ↔ LL5β(381–510); broader mapping also supports ERC1(200–400) ↔ LL5β(306–562); disruption fragments delocalize ERC1 and impair motility/invasion | (ribolla2023interferingwiththe pages 1-2, ribolla2023interferingwiththe pages 14-16, ribolla2023erc1controlledproteincondensates pages 60-64, ribolla2023erc1controlledproteincondensates pages 29-33, ribolla2023interferingwiththe pages 8-10) |
| Selected binding partners | Rab6 (Rab6B) via RBD; LL5β (direct); CLASPs indirectly via LL5β; liprin-α; RIM (PDZ); Bassoon/Piccolo (CAZ scaffolds) | (jin2023structuralbasisof pages 1-2, jin2023structuralbasisof pages 2-5, hida2010castandelks pages 2-3, astro2015plasmamembrane–associatedplatforms pages 4-5) |
| Primary cellular localizations | Presynaptic active zone (CAZ); cortical plasma membrane–associated platforms (PMAPs) at cell edge; secretion hotspots in pancreatic β-cells | (hida2010castandelks pages 2-3, astro2015plasmamembrane–associatedplatforms pages 4-5, fye2023insulinsecretionhot pages 1-2) |
| Representative recent papers (month/year; URL/DOI) | 1) Hida & Ohtsuka, Journal of Biochemistry (Aug 2010); https://doi.org/10.1093/jb/mvq065 (hida2010castandelks pages 2-3) 2) Astro & de Curtis, Science Signaling (Mar 2015); https://doi.org/10.1126/scisignal.aaa3312 (astro2015plasmamembrane–associatedplatforms pages 4-5) 3) Jin et al., JBC (Jun 2023); https://doi.org/10.1016/j.jbc.2023.104808 (jin2023structuralbasisof pages 1-2) 4) Ribolla et al., PLOS ONE (Jul 2023); https://doi.org/10.1371/journal.pone.0287670 (ribolla2023interferingwiththe pages 1-2) 5) de la Cruz et al., Nature Neuroscience (Mar 2024); https://doi.org/10.1038/s41593-024-01592-9 (cruz2024liprinαproteinsare pages 1-2) 6) Fye & Kaverina, Frontiers Cell Dev Biol (May 2023); https://doi.org/10.3389/fcell.2023.1211482 (fye2023insulinsecretionhot pages 1-2) |
(hida2010castandelks pages 2-3, astro2015plasmamembrane–associatedplatforms pages 4-5, jin2023structuralbasisof pages 1-2, ribolla2023interferingwiththe pages 1-2, cruz2024liprinαproteinsare pages 1-2, fye2023insulinsecretionhot pages 1-2) |
Table: Concise reference for human ERC1 (ELKS/Rab6IP2; UniProt Q8IUD2), highlighting domains, mapped interaction regions, partners, localizations, and key papers. Citations link to primary structural/functional evidence and recent reviews.
ERC1/ELKS is primarily a scaffold/adaptor (not an enzyme or transporter). Its functions arise from:
* Protein–protein interactions (e.g., Rab6B, LL5β, RIM1, Bassoon/Piccolo, liprin-α) that assemble multi-protein architectures at membrane-associated release sites. (jin2023structuralbasisof pages 2-5, hida2010castandelks pages 2-3, astro2015plasmamembrane–associatedplatforms pages 4-5)
* Higher-order assembly/condensation (LLPS-like behavior) that can concentrate binding partners and vesicles, improving capture and secretion efficiency. (jin2023structuralbasisof pages 1-2, jin2023structuralbasisof pages 2-5)
A widely used conceptual model is that ERC1 combines intrinsically disordered regions (IDRs) plus extensive coiled-coils to drive scaffold assembly, with short motifs conferring specific partner binding:
* In a 2023 mechanistic study, ELKS proteins are described as having an N-terminal IDR, a long central coiled-coil, and a C-terminal PDZ-binding motif, with the Rab6-binding site mapping to the C-terminal portion of the coiled-coil. (jin2023structuralbasisof pages 1-2)
* A foundational review of CAST/ELKS emphasizes multiple coiled-coil regions and a C-terminal IWA motif that binds the PDZ domain of RIM1, placing ERC1/ELKS within the canonical presynaptic active-zone scaffold network. (hida2010castandelks pages 2-3)
A major recent advance is the structural and mechanistic characterization of how ELKS1/ ERC1 binds Rab6B:
* The Rab6-binding domain (RBD) was mapped to ELKS1 residues 849–922 and shown to bind active Rab6B (Q72L) but not inactive Rab6B. (jin2023structuralbasisof pages 2-5)
* Binding affinity for ELKS1_RBD and ELKS2_RBD to Rab6B(Q72L) was reported at approximately ~8 μM by ITC. (jin2023structuralbasisof pages 1-2)
* A 2.04 Å crystal structure revealed the RBD forms a helical hairpin and engages Rab6B via switch regions and an interswitch interface with salt bridges and hydrophobic packing; structure-guided mutations disrupt binding and cellular recruitment of Rab6 variants to ELKS puncta. (jin2023structuralbasisof pages 2-5)
* Mechanistically, ELKS1 LLPS/condensation is proposed to enhance vesicle capture by competing with other Rab6 effectors and accumulating Rab6B-coated vesicles/liposomes into ELKS condensates, thereby promoting exocytosis of Rab6-positive cargo (e.g., neuropeptide Y). (jin2023structuralbasisof pages 1-2, jin2023structuralbasisof pages 2-5)
Visual evidence: the domain schematic and Rab6B–RBD complex structure are shown in Jin et al. (JBC, Jun 2023). (jin2023structuralbasisof media 8d6845af, jin2023structuralbasisof media 581dfe24)
In migrating cancer cells, ERC1 functions in plasma membrane–associated platforms (PMAPs) at the leading edge:
* A 2023 study mapped a minimal direct interaction between ERC1(270–370) and LL5β(381–510), described as a reversible, high-affinity interaction between predicted disordered regions; NMR supported disorder and binding. (ribolla2023interferingwiththe pages 1-2)
* Expression of these fragments disrupted the full-length complex, delocalized endogenous ERC1 from the cell edge, and reduced invasion-related behaviors such as invadopodia density and transwell invasion, supporting ERC1’s role in invasion/motility programs. (ribolla2023interferingwiththe pages 1-2, ribolla2023interferingwiththe pages 16-19)
A 2024 Nature Neuroscience study in human neurons supports a hierarchical assembly model:
* Presynaptic cell adhesion molecules recruit liprin-α, and liprin-α then recruits presynaptic components via a direct interaction with ELKS proteins, linking adhesion to active-zone scaffold assembly. (cruz2024liprinαproteinsare pages 1-2)
* In human neurons lacking liprin-α1–4, nascent contacts form but active-zone recruitment and synaptic vesicle accumulation fail, producing “empty” boutons and loss of transmission—placing ELKS-dependent scaffolding as part of a mechanism required for functional presynapse formation. (cruz2024liprinαproteinsare pages 1-2)
ERC1 is used as a mechanistic handle for understanding where secretion occurs:
* A Science Signaling review describes ELKS1 (ERC1) as a core component of plasma membrane–associated platforms (PMAPs) that colocalize with LL5β, CLASP, and liprin-α1 at the cortex and act as preferred docking/fusion sites for Rab6-positive Golgi-derived vesicles, reducing docking-to-fusion delay. (astro2015plasmamembrane–associatedplatforms pages 4-5)
* In pancreatic β cells, a 2023 perspective describes ELKS (ERC1) as a key insulin secretion “hot spot” scaffold protein, part of a protein ensemble shared with neuronal active zones and integrated with cytoskeletal/adhesion regulation. (fye2023insulinsecretionhot pages 1-2)
Although the native ERC1 protein is a scaffold, ERC1 genomic rearrangements can create kinase fusion oncogenes where ERC1 contributes oligomerization/coiled-coil features to activate the fused kinase.
RET fusions (ERC1–RET):
* In a large Chinese multicancer NGS study (publication Nov 2022), ERC1 was among the most common RET fusion partners (alongside KIF5B and CCDC6). The study reported overall prevalence of functional RET fusions of 1.05% in lung cancer, 6.03% in thyroid cancer, and 0.39% in colorectal cancer (with <0.1% in gastric and hepatocellular carcinoma). (shi2022identificationofret pages 1-2)
* A 2023 papillary thyroid carcinoma case report with ERC1–RET documented clinical response to selpercatinib: after switching from lenvatinib to selpercatinib, tumors shrank by 10 weeks and serum thyroglobulin fell 851 ng/mL → 68.1 ng/mL. (toda2023lenvatinibandselpercatinib pages 1-2)
FGFR2–ERC1:
* A 2022 lung adenocarcinoma case report identified FGFR2–ERC1 and noted that FGFR fusions in NSCLC are rare (reported 0.20% overall FGFR fusion rate; 0.04% FGFR2 fusion rate in a 26,054-sample series). The patient achieved a >8 month progression-free interval on anlotinib (a multi-kinase inhibitor with FGFR activity). (hong2022fgfr2erc1asubtype pages 1-2)
Across neurons, endocrine cells, and motile cells, ERC1 appears to implement a general design principle: create spatially restricted release “sites” by assembling scaffolds at the plasma membrane that:
1) recruit cytomatrix/cortical components (e.g., liprin-α, LL5β/CLASP),
2) engage trafficking GTPases (Rab6 family) and capture secretory carriers,
3) accelerate or bias vesicle docking/fusion to those sites.
This synthesis is supported by active-zone scaffold biology (RIM/CAST/ELKS networks) (hida2010castandelks pages 2-3), PMAP/exocytosis reviews (astro2015plasmamembrane–associatedplatforms pages 4-5), and recent structure/LLPS mechanism work (jin2023structuralbasisof pages 1-2, jin2023structuralbasisof pages 2-5).
One source (a 2025 preprint) discusses ERC1 as a regulatory subunit of the IKK complex and suggests NF-κB signaling roles; because this is not part of the 2023–2024 peer-reviewed core ERC1 literature assembled here, this report treats it as suggestive but not definitive for functional annotation of ERC1’s primary role. (ashraf2025prevalenceandfunctional pages 29-31)
References
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