ARCN1 (P48444) – Coatomer Subunit Delta in Human Cells

Overview and Key Concepts

ARCN1, also known as archain 1 or coatomer subunit δ (delta), is a gene encoding a critical subunit of the COPI (coat protein I) vesicle coat complex. COPI is a hetero-heptameric protein complex responsible for forming coated transport vesicles, particularly in the early secretory pathway (pmc.ncbi.nlm.nih.gov) (www.frontiersin.org). ARCN1’s protein product (δ-COP) is a structural adapter protein – it does not catalyze chemical reactions but instead helps assemble the COPI coat and select cargo for vesicular transport. This coatomer complex is highly conserved across eukaryotes; in model organisms like yeast, flies, and worms, loss-of-function mutations in the ARCN1 ortholog are lethal, underscoring its fundamental role (journals.plos.org). In human cells, ARCN1 is essential for maintaining normal intracellular protein trafficking and organelle organization (journals.plos.org) (journals.plos.org).

Current understanding defines ARCN1/δ-COP as a core component of the COPI coat needed for intracellular protein transport between the endoplasmic reticulum (ER) and Golgi apparatus (pmc.ncbi.nlm.nih.gov). COPI-coated vesicles mediate retrograde transport – the retrieval of proteins from the Golgi back to the ER – and also contribute to intra-Golgi transport (within Golgi stacks) (journals.plos.org). Classic studies first identified COPI in mammalian cells as a cytosolic complex that coats Golgi-derived vesicles (journals.plos.org), initially linking it to retrograde traffic from the cis-Golgi to the rough ER (journals.plos.org). Subsequent research expanded this view: COPI (and by extension ARCN1) also functions in anterograde ER-to-Golgi transport and general secretory pathway maintenance, as suggested by yeast mutants where δ-COP is required for both directions of ER–Golgi traffic (journals.plos.org). Beyond the ER–Golgi shuttling, recent reviews emphasize that COPI-coated vesicles participate in diverse cellular processes — including endosome maturation, lipid homeostasis, autophagy, and even viral infection cycles — highlighting the broader significance of ARCN1’s role as part of this coat complex (www.frontiersin.org). Importantly, ARCN1 is not an enzyme or a transporter on its own; rather, it acts as an adaptor/structural scaffold within COPI, helping to recognize sorting signals on cargo and to sculpt membrane vesicles for transport. In summary, ARCN1’s primary function is to enable COPI-mediated vesicle formation and cargo selection in the early secretory pathway, a process vital for cellular homeostasis (pmc.ncbi.nlm.nih.gov) (journals.plos.org).

Structure and Localization of ARCN1 Protein

The ARCN1-encoded protein (δ-COP) is about 400–500 amino acids in length and is one of the “lighter” subunits of coatomer, in contrast to several larger COPI subunits (~α-, β-, β′-, γ-COP) that are over 900 amino acids. Structurally, δ-COP contains an N-terminal longin domain followed by linker helices and a C-terminal μ-homology domain (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Longin domains are a hallmark of many vesicle coat proteins (also found in small subunits of clathrin adaptor complexes) and typically mediate membrane or GTPase interactions. Indeed, high-resolution structural studies (e.g. eLife, 2017) reveal that δ-COP’s longin domain and adjacent helices interface intimately with β-COP, forming a stable subcomplex (journals.plos.org). ARCN1 and β-COP bind each other directly – a finding first shown in yeast and confirmed in mammalian cells by co-localization experiments (journals.plos.org). Cryo-EM and crystallography have further mapped how ARCN1 (δ-COP) fits into the assembled COPI coat: δ-COP’s helical segments “dock” along the α-solenoid rod of β-COP and one helix (helix b in the structure) projects outward to contact the small GTPase Arf1 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Arf1·GTP is the molecule that recruits coatomer to the membrane, and δ-COP directly contacting Arf1 suggests ARCN1 helps anchor the coat to the membrane surface (pmc.ncbi.nlm.nih.gov). Notably, the tip of δ-COP’s helix also reaches the lipid bilayer, indicating ARCN1 plays a role in positioning the coatomer on the membrane vesicle bud (pmc.ncbi.nlm.nih.gov).

Within the coatomer complex, ARCN1 (δ-COP) and another small subunit ζ-COP are considered functionally analogous to clathrin-adaptor proteins (pmc.ncbi.nlm.nih.gov). Both δ- and ζ-COP share homology with subunits of clathrin AP complexes and were shown to be specifically required for ER retrieval signals in the mid-1990s (pmc.ncbi.nlm.nih.gov). In particular, δ-COP is critical for recognizing sorting motifs in cargo proteins: one classic example is the dilysine (KKXX) motif found in the cytosolic tails of ER-resident membrane proteins. The COPI coat binds these KKXX signals to recycle such proteins back to the ER (pmc.ncbi.nlm.nih.gov). Early biochemical work demonstrated coatomer’s direct interaction with KKXX motifs (pmc.ncbi.nlm.nih.gov), and loss of δ- or ζ-COP disrupts this retrieval pathway (pmc.ncbi.nlm.nih.gov). More recent mechanistic studies refined our understanding of ARCN1’s role in cargo binding: a 2007 J. Cell Biol. study identified a novel cargo-binding site formed at the interface of the β- and δ-COP subunits (pmc.ncbi.nlm.nih.gov). Mutational analysis showed that conserved sequence patches in ARCN1 (δ-COP) together with β-COP are specifically required to recognize arginine-based ER retention signals (di-Arg motifs) on unassembled membrane protein subunits (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). When a segment of δ-COP and a few residues of β-COP were altered, COPI lost the ability to bind these R-based signals (causing mis-localization of reporter proteins), even though binding to C-terminal dilysine signals remained intact (pmc.ncbi.nlm.nih.gov). This finding indicates that ARCN1 is directly involved in cargo selection: it helps create a binding pocket for certain retrieval motifs, thereby conferring substrate specificity to the COPI coat for retrieving proteins that should not advance through the secretory pathway. Taken together, ARCN1 serves a structural role in assembling the COPI coat and an adaptory role in cargo recognition – analogous to how clathrin adaptors work – ensuring that vesicles incorporate the correct proteins.

Subcellular localization: As a COPI coat subunit, ARCN1 protein dynamically cycles between the cytosol and Golgi membranes. Under steady-state conditions, a substantial pool of δ-COP (and the coatomer complex) resides in the cytoplasm when unassembled. Upon activation of Arf1 on Golgi or ER-Golgi intermediate compartment membranes, ARCN1 is recruited to the membrane, along with other coatomer subunits, to form the vesicle coat (pmc.ncbi.nlm.nih.gov). Immunofluorescence microscopy confirms that ARCN1 localizes to the early secretory organelles: it shows a punctate staining pattern co-distributed with Golgi markers and with ER markers in the cell periphery (journals.plos.org). In cultured cells, δ-COP puncta often overlap with β-COP puncta at the ER and Golgi, consistent with both being parts of the same coatomer complexes (journals.plos.org). For example, primary mouse melanocytes stained with anti-ARCN1 reveal ARCN1 on vesicular structures around the Golgi and ER exit sites, and these structures co-stain for β-COP (journals.plos.org). This punctate localization represents COPI-coated transport intermediates. Interestingly, researchers have noted that not all ARCN1 puncta colocalize with β-COP, suggesting that some δ-COP might exist temporarily unassembled or in subcomplexes apart from the full coat (journals.plos.org). This raises the possibility (still under investigation) that ARCN1 could have independent functions or assembly states outside the classic heptameric COPI coat (journals.plos.org). Nonetheless, the predominant localization and function of ARCN1 are tied to the ER–Golgi network. Disrupting ARCN1’s function (for instance, by siRNA knockdown or drug treatment) causes redistribution of Golgi proteins and loss of normal Golgi morphology, indicating COPI’s role (and ARCN1’s) in maintaining Golgi structure and compartmentalization (journals.plos.org) (journals.plos.org). Moreover, the drug brefeldin A (which inactivates Arf1) acutely releases coatomer from membranes; cells treated with brefeldin A show ARCN1/coatomer entirely in the cytosol and concomitant collapse of Golgi organization (journals.plos.org). This pharmacological context further confirms that ARCN1 acts at Golgi membranes and that its membrane association is ARF1-dependent and required for normal organelle integrity.

Functional Role in Biological Pathways

Primary function: ARCN1’s central role is in the COPI-mediated vesicular transport pathway, which is a fundamental part of the secretory and endomembrane system. The COPI pathway regulated by ARCN1 can be summarized as follows: activated Arf1-GTP on the Golgi recruits the ARCN1-containing coatomer complex to the membrane, where the coat polymerizes into a cage-like lattice that shapes a budding vesicle (pmc.ncbi.nlm.nih.gov). During this assembly, ARCN1 (δ-COP) and its partner subunits capture specific cargo proteins bearing ER retrieval signals (like KKXX or RR motifs) into the nascent vesicle (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The vesicle then pinches off carrying the cargo, and shortly thereafter the GTP on Arf1 is hydrolyzed (often stimulated by ArfGAP), which triggers coatomer disassembly/uncoating (pmc.ncbi.nlm.nih.gov). The uncoated vesicle can fuse with the target compartment (typically the ER or an earlier Golgi cisterna), delivering the retrieved proteins back. Through this cycle, ARCN1 ensures that escaped ER-resident proteins are returned to the ER, and that Golgi-resident enzymes are recycled, thereby maintaining the identity and function of the ER and Golgi. This retrograde transport is crucial for protein quality control (e.g. returning misfolded proteins or chaperones to the ER) and for recycling trafficking machinery (like SNARE proteins or KDEL receptors) to their proper location (journals.plos.org). Consistently, cells depleted of COPI/ARCN1 show accumulation of proteins in the wrong compartments, ER stress, and disrupted glycoprotein processing (journals.plos.org) (pmc.ncbi.nlm.nih.gov). ARCN1’s function is tightly connected to the COPII pathway as well: COPII mediates forward (anterograde) transport from ER to Golgi, and COPI (with ARCN1) retrieves components back to the ER. Together, these pathways form a cycle that balances protein flow. If ARCN1/COPI function is impaired, anterograde cargo (like secreted proteins) can get stuck or mis-sorted due to failure of recycling. For example, recent human genetic studies showed that collagen, a large secretory protein, depends on proper COPI function for secretion – cells from ARCN1-deficient patients had defective type I collagen transport and greatly reduced collagen secretion (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In these patients, collagen accumulated inside cells (triggering stress), correlating with skeletal abnormalities in the ARCN1 syndrome. This highlights ARCN1’s precise role in ensuring large cargo like procollagen can be processed and exported, likely by recycling specific enzymes or chaperones needed for collagen maturation (pmc.ncbi.nlm.nih.gov).

Beyond the ER–Golgi shuttle, ARCN1 (as part of COPI) is implicated in other trafficking routes. There is evidence that COPI-coated vesicles participate in endosomal transport – for instance, COPI may help form carriers that retrieve membrane proteins from early endosomes back to the trans-Golgi network (TGN) or maintain endosome maturation (pmc.ncbi.nlm.nih.gov) (www.frontiersin.org). In cells with ARCN1 knocked down, endocytic tracers show delays in reaching late endosomes (pmc.ncbi.nlm.nih.gov), suggesting that COPI might indirectly support endosomal sorting (possibly by recycling membrane components between endosomes and Golgi). COPI and ARCN1 have also been linked to autophagy and lipid droplet biology in recent studies (www.frontiersin.org). In autophagy, COPI vesicles can bud from Golgi or endosomal membranes to deliver enzymes or lipids needed for autophagosome formation (though the exact contribution of δ-COP is still being explored). Lipid homeostasis is another emerging area – for example, COPI machinery was shown to act on lipid droplets in cells to regulate their protein coat and exchange with ER membranes (this involves ARF1/COPI activity on the droplet surface) (www.frontiersin.org). All these roles underscore that ARCN1’s broader functional repertoire extends to multiple membrane trafficking pathways, even if its canonical role remains the retrograde ER–Golgi transport. It’s worth noting that each COPI subunit might have unique interactions: a recent 2022 analysis pointed out that different COPI subunit mutations cause distinct human disorders (e.g. COPA mutations cause autoimmune lung/kidney disease, COPB2 mutations cause a failure in craniofacial development, etc.), raising the possibility that subunits like ARCN1 have non-canonical functions outside the core COPI vesicle cycle (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). While these subunit-specific roles are not fully defined, experts suggest they could involve selective cargo or tissue-specific interactions that go beyond general COPI coat duties (pmc.ncbi.nlm.nih.gov). For ARCN1, however, no separate pathway has been definitively proven, and current data still tie its importance to the proper functioning of COPI-mediated transport.

Biological Impact and Evidence from Research

Multiple lines of experimental evidence illustrate ARCN1’s function and importance:

• Cellular and biochemical studies: Depletion or mutation of ARCN1 disrupts vesicle trafficking and organelle morphology. For example, mouse cells harboring a hypomorphic Arcn1 mutation (the nur17 mutant) showed abnormal accumulation of proteins in the ER, ER stress markers activation, and disorganized Golgi (journals.plos.org). In those cells, cargo transport assays demonstrated delays in ER-to-Golgi trafficking, indicating δ-COP is required for efficient forward movement of proteins or for maturation steps (journals.plos.org). Similarly, siRNA knockdown of ARCN1 in cultured human cells leads to fragmentation of the Golgi and mislocalization of ER/Golgi proteins (journals.plos.org) (journals.plos.org). These phenotypes are consistent with a failure of vesicle recycling – for instance, Golgi enzymes might not return to Golgi after mistargeting, causing Golgi dysfunction. On a molecular level, ARCN1 was shown (by co-immunoprecipitation and microscopy) to co-complex with β-COP and other COPI subunits (journals.plos.org), confirming it is an integral part of coatomer and not a solitary actor. The ARF1 dependence of ARCN1 membrane binding is demonstrated by brefeldin A treatment experiments and by structural data showing δ-COP contacts Arf1 directly (pmc.ncbi.nlm.nih.gov). These lines of evidence support the model that ARCN1 works as a membrane-bound coat protein for vesicle formation, controlled by Arf1’s GTP/GDP state.

• Genetic studies in model organisms: In yeast, the δ-COP ortholog (Sec28 or Ret3, depending on species) is essential for viability; yeast mutants exhibited pronounced secretion defects and Golgi stress (journals.plos.org) (journals.plos.org). In Drosophila, an ARCN1 mutant is lethal at early stages (FlyBase notes archain as an essential gene) (journals.plos.org). In mice, a point mutation in Arcn1 (nur17, causing a single amino acid change) was identified in a screen for neurological mutants: homozygous mutant mice had Purkinje cell degeneration in the cerebellum and a diluted coat color, linking COPI dysfunction to both neural degeneration and pigment cell trafficking issues (journals.plos.org) (journals.plos.org). The diluted coat color in mice is an interesting phenotypic readout, since pigment-producing melanocytes rely on vesicle trafficking (melanosome formation involves Golgi and endosomal transport). Indeed, melanocytes from Arcn1 mutant mice accumulated misprocessed melanosomal proteins, indicating trafficking delays in the ER–Golgi route (journals.plos.org) (journals.plos.org). Notably, introducing a wild-type ARCN1 transgene in these mutant mice could rescue the phenotype, directly proving that the observed defects were caused by loss of ARCN1 function (www.prolekarniky.cz). These animal studies provide causal evidence that ARCN1 is required for normal vesicle transport and cell physiology.

• Human genetics and disease: Perhaps the most compelling real-world evidence of ARCN1’s role comes from rare human syndromes caused by ARCN1 mutations. In 2016, Izumi et al. reported a distinctive craniofacial and skeletal syndrome in individuals with heterozygous ARCN1 loss-of-function mutations (pmc.ncbi.nlm.nih.gov). Affected patients had features like micrognathia (small jaw), growth retardation, rhizomelic shortening of limbs, and mild developmental delay (pmc.ncbi.nlm.nih.gov). Cellular analysis of patient-derived cells revealed activation of the unfolded protein response (ER stress) and a deficit in secreting type I procollagen (pmc.ncbi.nlm.nih.gov). This aligns perfectly with ARCN1’s role in ER–Golgi transport: without full COPI function, large proteins like collagen are not efficiently exported, leading to ER stress and downstream developmental issues. Subsequent studies have expanded the phenotypic spectrum of ARCN1-related syndrome (OMIM #617164). By 2022, at least a dozen patients were documented, showing consistent facial dysmorphisms and short stature, and some had additional features like liver dysfunction or cataracts (pmc.ncbi.nlm.nih.gov). All pathogenic variants were either null or severely hypomorphic, confirming that the syndrome stems from ARCN1 haploinsufficiency (half-quantity of coatomer δ subunit is not enough for full function) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These human mutations cement ARCN1’s importance: even a partial loss of ARCN1 impairs COPI-mediated transport enough to cause multi-system developmental defects. The unique clinical manifestations (e.g. skeletal defects from collagen misrouting) also serve to elucidate ARCN1’s precise role in pathways like collagen biosynthesis and secretion, which were not obvious from cell studies alone (pmc.ncbi.nlm.nih.gov). Thus, human genetics has provided both a confirmation of ARCN1’s function and insight into which physiological pathways (e.g. bone formation via collagen) are most sensitive to COPI dysfunction.

• Pathogen exploitation: In real-world scenarios, some pathogens hijack the host’s COPI/ARCN1 machinery for their own life cycle. A notable example is Influenza virus. Genome-wide siRNA screens identified ARCN1 and other COPI subunits as host factors that the influenza virus requires for infection (pmc.ncbi.nlm.nih.gov). Follow-up virology experiments showed that when ARCN1 is depleted in human cells, influenza virus entry is impaired – viruses have defects in internalization and trafficking to late endosomes (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Additionally, COPI disruption led to reduced surface expression of viral envelope proteins and diminished assembly of new virions (pmc.ncbi.nlm.nih.gov). In other words, without ARCN1, the virus has trouble both getting into the cell efficiently and producing progeny. This indicates that COPI-mediated transport (potentially recycling of endosomal components or proper routing of viral proteins to assembly sites) is crucial for influenza’s life cycle. Similar dependencies on COPI have been reported for other viruses (e.g. vesicular stomatitis virus) (pmc.ncbi.nlm.nih.gov). From a therapeutic angle, this suggests ARCN1 or COPI function could be a target for broad-spectrum antivirals, although given the essential role of ARCN1 in host cells, direct targeting would need to be carefully modulated to avoid host toxicity. Still, the virus studies highlight a “real-world” implementation of basic cell biology: viruses reveal which host pathways are most indispensable by failing to propagate when those pathways (like ARCN1/COPI) are knocked down.

• Expert analysis and recent advances: Authoritative reviews and structural biology studies in the last few years have enriched our understanding of ARCN1’s mechanism. A 2017 cryo-EM analysis achieved ~9Å resolution of the assembled COPI coat and solved the crystal structure of a β–δ COP fragment, allowing researchers to build a detailed molecular model of coatomer (pmc.ncbi.nlm.nih.gov). This work, by Dodonova et al., showed how δ-COP (ARCN1) is positioned in the COPI lattice and interacts with Arf1 and other subunits, as described earlier (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). It provided visual confirmation that δ-COP’s C-terminal region (helix b/c) contacts the Arf1 GTPase and even touches the membrane, supporting theories that ARCN1 helps stabilize the coat on curved membranes (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Additionally, a 2016 biochemical study identified a specific helix in δ-COP’s linker as “key to COPI dynamics and function”, meaning mutating that helix disrupted normal coat behavior (this corresponds to the same region later visualized by cryo-EM) (pmc.ncbi.nlm.nih.gov). Experts in the field (e.g. Wieland and colleagues, who discovered COPI) have noted that COPI operates with remarkable coordination, where each subunit like ARCN1 plays a part in timing coat assembly and cargo capture (pubmed.ncbi.nlm.nih.gov). Recent commentary also points out an intriguing observation: different COPI subunits, when mutated, lead to different diseases (COPA causing an autoimmunity syndrome, COPB2 causing a neurologic syndrome, ARCN1 causing the craniofacial syndrome, etc.), which suggests that while all subunits work together in vesicle formation, they might each interact with a unique subset of cargo or regulators (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This has led to a hypothesis in the field that ARCN1 (δ-COP) might have specialized interactions (perhaps with specific cargo like collagen or specific cell-type proteins) that are not fully redundant with other subunits (pmc.ncbi.nlm.nih.gov). Ongoing research in 2023–2024 is exploring these possibilities, as well as investigating COPI’s role in diseases like cancer. For instance, COPI subunits are often essential for rapidly dividing cells; one 2024 study noted that cancer cells are “addicted” to COPI subunit COPZ1 and require high coatomer activity to manage their elevated secretory load (www.frontiersin.org). Although that study focused on COPZ1, it underscores a general principle that applies to ARCN1: cells under stress (whether tumor cells or secretory cells like chondrocytes making collagen) have a heightened reliance on COPI-mediated trafficking.

Conclusion

In summary, ARCN1 (archain 1) encodes the delta subunit of the COPI coat complex, a pivotal player in the secretory pathway. Its primary role is structural and regulatory: ARCN1 helps assemble COPI-coated vesicles on Golgi membranes and selectively sort cargo (especially proteins that need to be returned to the ER) into these vesicles. Through this function, ARCN1 maintains the proper localization of proteins within the ER–Golgi network, supports protein quality control, and indirectly enables efficient secretion of proteins. It localizes to the cytosol and Golgi region, cycling on and off membranes in concert with Arf1 GTPase activity. Decades of research, from classic cell-free experiments to modern genomics, have built a consistent picture of ARCN1 as essential for vesicle trafficking and cell viability. The latest studies (2020s) have provided high-resolution insight into how ARCN1 interacts at the molecular level with cargo and coat partners (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), and human genetic data have illuminated the physiological consequences of its partial loss (pmc.ncbi.nlm.nih.gov). There is a strong consensus in the field – reflected in authoritative reviews and expert analyses – that ARCN1’s COPI-mediated transport function is indispensable for cellular homeostasis (pmc.ncbi.nlm.nih.gov) (journals.plos.org). As research progresses, scientists continue to investigate whether ARCN1 has any moonlighting roles outside of COPI and how COPI subunits like δ-COP might be leveraged in clinical contexts. Nonetheless, the core function of ARCN1 remains anchored in its role as a COPI coat adaptor, orchestrating the crucial flow of proteins between the Golgi and ER – a process fundamental to the life of the cell.

References: (Key sources with URLs and dates)

• Dodonova et al., eLife, June 2017 – 9Å structure of the COPI coat (structural model of β/δ-COP and Arf1 interactions) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Izumi et al., Am. J. Hum. Genet., Jul 28 2016 – ARCN1 mutations cause a craniofacial syndrome (clinical and cell evidence of COPI transport defects) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Xu et al., PLoS Genet., May 20 2010 – Archain 1 mutation in mice (nur17) (demonstrating ARCN1’s role in vesicle trafficking, neurodegeneration, ER stress) (journals.plos.org) (journals.plos.org).
• Michelsen et al., J. Cell Biol., Oct 22 2007 – Cargo-binding site in β/δ-COP (identifying ARCN1’s involvement in recognizing ER retention signals) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Cosson & Letourneur, EMBO J., Apr 15 1996 – δ- and ζ-COP homologous to adaptins, involved in ER retrieval (early evidence that ARCN1 is needed for KKXX signal–mediated retrieval) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Frontiers in Pharm., 2025 (ref. Bingham 2024) – COPI coatomer functions (review of COPI in trafficking, autophagy, viral processes) (www.frontiersin.org).
• Sun et al., J. Virol., Mar 2013 – COPI complexes in influenza infection (showing ARCN1 depletion hampers virus entry and replication) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Citations

1. AnnotationURLCitation(end_index=593, start_index=399, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=Cellular%20homeostasis%20is%20maintained%20by,facial%20dysmorphisms%2C%20severe%20micrognathia%2C%20rhizomelic')
2. AnnotationURLCitation(end_index=761, start_index=594, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
3. AnnotationURLCitation(end_index=1341, start_index=1165, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=mutations%20of%20Arcn1%20%28%CE%B4,all%20result%20in%20lethality')
4. AnnotationURLCitation(end_index=1616, start_index=1462, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
5. AnnotationURLCitation(end_index=1809, start_index=1617, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=Studies%20using%20mammalian%20cells%20with,to%20understand%20the%20function%20of')
6. AnnotationURLCitation(end_index=2197, start_index=2003, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=Cellular%20homeostasis%20is%20maintained%20by,facial%20dysmorphisms%2C%20severe%20micrognathia%2C%20rhizomelic')
7. AnnotationURLCitation(end_index=2533, start_index=2384, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=,mutant%20for%20the%20yeast%20homolog')
8. AnnotationURLCitation(end_index=2832, start_index=2649, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=ARCN1%2C%20also%20known%20as%20%CE%B4,based%20on%20studies%20in%20yeast')
9. AnnotationURLCitation(end_index=3061, start_index=2912, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=,mutant%20for%20the%20yeast%20homolog')
10. AnnotationURLCitation(end_index=3536, start_index=3326, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=compartments%2C%20proper%20Golgi%20structure%2C%20ER,in%20primary%20cultured%20mouse%20melanocytes')
11. AnnotationURLCitation(end_index=4013, start_index=3846, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
12. AnnotationURLCitation(end_index=4611, start_index=4417, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=Cellular%20homeostasis%20is%20maintained%20by,facial%20dysmorphisms%2C%20severe%20micrognathia%2C%20rhizomelic')
13. AnnotationURLCitation(end_index=4766, start_index=4612, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
14. AnnotationURLCitation(end_index=5279, start_index=5167, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=model%20of%20%CE%B4,solenoid')
15. AnnotationURLCitation(end_index=5417, start_index=5280, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=size%20of%201737%20%C3%85,helix%20a%20is%20in%20close')
16. AnnotationURLCitation(end_index=5973, start_index=5779, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=cytoplasm%20suggesting%20its%20localization%20in,also%20noted%20that%20there%20are')
17. AnnotationURLCitation(end_index=6307, start_index=6113, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=cytoplasm%20suggesting%20its%20localization%20in,also%20noted%20that%20there%20are')
18. AnnotationURLCitation(end_index=6727, start_index=6577, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=match%20at%20L640%20Helix%20a,b%20also%20contacts%20the%20membrane')
19. AnnotationURLCitation(end_index=6883, start_index=6728, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
20. AnnotationURLCitation(end_index=7205, start_index=7050, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
21. AnnotationURLCitation(end_index=7514, start_index=7359, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
22. AnnotationURLCitation(end_index=7765, start_index=7664, title='Architecture of coatomer: molecular characterization of delta-COP and protein interactions within the complex - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2121028/#:~:text=,Google%20Scholar')
23. AnnotationURLCitation(end_index=8029, start_index=7928, title='Architecture of coatomer: molecular characterization of delta-COP and protein interactions within the complex - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2121028/#:~:text=,Google%20Scholar')
24. AnnotationURLCitation(end_index=8410, start_index=8309, title='Delta- and zeta-COP, two coatomer subunits homologous to clathrin-associated proteins, are involved in ER retrieval - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC450095/#:~:text=4,Google%20Scholar')
25. AnnotationURLCitation(end_index=8596, start_index=8495, title='Delta- and zeta-COP, two coatomer subunits homologous to clathrin-associated proteins, are involved in ER retrieval - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC450095/#:~:text=4,Google%20Scholar')
26. AnnotationURLCitation(end_index=8755, start_index=8654, title='Architecture of coatomer: molecular characterization of delta-COP and protein interactions within the complex - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2121028/#:~:text=,Google%20Scholar')
27. AnnotationURLCitation(end_index=9114, start_index=8973, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Pmp2%20fused%20to%20GFP%20and,based%20signals%20by%20COPI')
28. AnnotationURLCitation(end_index=9482, start_index=9348, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Arginine%20%28R%29,COPI%20coat%20that%20had%20lost')
29. AnnotationURLCitation(end_index=9624, start_index=9483, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Pmp2%20fused%20to%20GFP%20and,based%20signals%20by%20COPI')
30. AnnotationURLCitation(end_index=10001, start_index=9860, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Pmp2%20fused%20to%20GFP%20and,based%20signals%20by%20COPI')
31. AnnotationURLCitation(end_index=11122, start_index=10950, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=COPI%20coated%20vesicles%20mediate%20trafficking,structures%20we%20built%20a%20molecular')
32. AnnotationURLCitation(end_index=11524, start_index=11344, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=whole%20animal%20have%20not%20been,partner%20of%20ARCN1%20in%20yeast')
33. AnnotationURLCitation(end_index=11869, start_index=11675, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=cytoplasm%20suggesting%20its%20localization%20in,also%20noted%20that%20there%20are')
34. AnnotationURLCitation(end_index=12205, start_index=12047, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=using%20anti,also%20noted%20that%20there%20are')
35. AnnotationURLCitation(end_index=12635, start_index=12484, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=Figure%204Aiii%20,COP%20or%20the%20COPI')
36. AnnotationURLCitation(end_index=12991, start_index=12801, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=present%20in%20a%20complex%20with,required%20to%20test%20these%20possibilities')
37. AnnotationURLCitation(end_index=13500, start_index=13346, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
38. AnnotationURLCitation(end_index=13693, start_index=13501, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=Studies%20using%20mammalian%20cells%20with,to%20understand%20the%20function%20of')
39. AnnotationURLCitation(end_index=14073, start_index=13919, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
40. AnnotationURLCitation(end_index=14879, start_index=14722, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=COPI%20coated%20vesicles%20mediate%20trafficking,57%20%C3%85%20resolution')
41. AnnotationURLCitation(end_index=15158, start_index=15057, title='Delta- and zeta-COP, two coatomer subunits homologous to clathrin-associated proteins, are involved in ER retrieval - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC450095/#:~:text=4,Google%20Scholar')
42. AnnotationURLCitation(end_index=15300, start_index=15159, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Pmp2%20fused%20to%20GFP%20and,based%20signals%20by%20COPI')
43. AnnotationURLCitation(end_index=15652, start_index=15480, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=COPI%20coated%20vesicles%20mediate%20trafficking,structures%20we%20built%20a%20molecular')
44. AnnotationURLCitation(end_index=16398, start_index=16244, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
45. AnnotationURLCitation(end_index=16734, start_index=16549, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=neurological%2017%20,the%20mechanisms%20of%20neurodegenerative%20diseases')
46. AnnotationURLCitation(end_index=16917, start_index=16735, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=function%20heterozygous%20mutations%20in%20ARCN1%2C,ARCN1%20deficiency%20causes%20defective%20type')
47. AnnotationURLCitation(end_index=17768, start_index=17583, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=function%20heterozygous%20mutations%20in%20ARCN1%2C,including%20skeletogenesis%20and%20brain%20growth')
48. AnnotationURLCitation(end_index=17910, start_index=17769, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=in%202016%20and%20is%20characterized,2%20%2C%205%7D%20The')
49. AnnotationURLCitation(end_index=18425, start_index=18240, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=function%20heterozygous%20mutations%20in%20ARCN1%2C,including%20skeletogenesis%20and%20brain%20growth')
50. AnnotationURLCitation(end_index=18960, start_index=18783, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=revealed%20influenza%20virus%20host%20dependency,defects%20in%20virus%20internalization%20and')
51. AnnotationURLCitation(end_index=19128, start_index=18961, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
52. AnnotationURLCitation(end_index=19385, start_index=19221, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=dissection%20of%20the%20influenza%20virus,influenza%20virus%20entry%20but%20play')
53. AnnotationURLCitation(end_index=19793, start_index=19626, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
54. AnnotationURLCitation(end_index=20403, start_index=20236, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
55. AnnotationURLCitation(end_index=21167, start_index=21034, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=of%20COPI,variants%20in%20COPB2%20cause%20primary')
56. AnnotationURLCitation(end_index=21315, start_index=21168, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=distinctively%20different%2C%20despite%20all%20encoding,related')
57. AnnotationURLCitation(end_index=21645, start_index=21498, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=distinctively%20different%2C%20despite%20all%20encoding,related')
58. AnnotationURLCitation(end_index=22462, start_index=22277, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=neurological%2017%20,the%20mechanisms%20of%20neurodegenerative%20diseases')
59. AnnotationURLCitation(end_index=22799, start_index=22647, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=,trafficking%20or%20defects%20in%20intra')
60. AnnotationURLCitation(end_index=23096, start_index=22942, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
61. AnnotationURLCitation(end_index=23289, start_index=23097, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=Studies%20using%20mammalian%20cells%20with,to%20understand%20the%20function%20of')
62. AnnotationURLCitation(end_index=23790, start_index=23596, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=cytoplasm%20suggesting%20its%20localization%20in,also%20noted%20that%20there%20are')
63. AnnotationURLCitation(end_index=24182, start_index=24027, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
64. AnnotationURLCitation(end_index=24667, start_index=24543, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=,COP%29%20in')
65. AnnotationURLCitation(end_index=24844, start_index=24668, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=mutations%20of%20Arcn1%20%28%CE%B4,all%20result%20in%20lethality')
66. AnnotationURLCitation(end_index=25126, start_index=24950, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=mutations%20of%20Arcn1%20%28%CE%B4,all%20result%20in%20lethality')
67. AnnotationURLCitation(end_index=25636, start_index=25453, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=The%20fact%20that%20mutations%20in,gene%20encoding%20a%20component%20of')
68. AnnotationURLCitation(end_index=25822, start_index=25637, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=neurological%2017%20,the%20mechanisms%20of%20neurodegenerative%20diseases')
69. AnnotationURLCitation(end_index=26364, start_index=26168, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=ARCN1%20is%20involved%20in%20ER%E2%80%93Golgi,Golgi%20trafficking%20in%20melanocytes')
70. AnnotationURLCitation(end_index=26557, start_index=26365, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=Studies%20using%20mammalian%20cells%20with,to%20understand%20the%20function%20of')
71. AnnotationURLCitation(end_index=26997, start_index=26740, title='Mutation in Archain 1, a Subunit of COPI Coato... | proLékárníky.cz', type='url_citation', url='https://www.prolekarniky.cz/casopisy/plos-genetics/2010-5/mutation-in-archain-1-a-subunit-of-copi-coatomer-complex-causes-diluted-coat-color-and-purkinje-cell-degeneration-44762#:~:text=proL%C3%A9k%C3%A1rn%C3%ADky,We%20generated%20a')
72. AnnotationURLCitation(end_index=27620, start_index=27433, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=dysplasia%20and%20osteogenesis%20imperfect%2C%20caused,collagen%20secretion%20represents%20the%20likely')
73. AnnotationURLCitation(end_index=27954, start_index=27769, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=dysplasia%20and%20osteogenesis%20imperfect%2C%20caused,ARCN1%20deficiency%20causes%20defective%20type')
74. AnnotationURLCitation(end_index=28299, start_index=28114, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=function%20heterozygous%20mutations%20in%20ARCN1%2C,including%20skeletogenesis%20and%20brain%20growth')
75. AnnotationURLCitation(end_index=28893, start_index=28789, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=ARCN1,4%2C3%7D%20The')
76. AnnotationURLCitation(end_index=29239, start_index=29100, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=This%20study%20aimed%20to%20describe,related%20syndrome')
77. AnnotationURLCitation(end_index=29373, start_index=29240, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=of%20COPI,variants%20in%20COPB2%20cause%20primary')
78. AnnotationURLCitation(end_index=29956, start_index=29771, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=function%20heterozygous%20mutations%20in%20ARCN1%2C,including%20skeletogenesis%20and%20brain%20growth')
79. AnnotationURLCitation(end_index=30607, start_index=30461, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=As%20an%20obligate%20pathogen%2C%20influenza,Upon%20systematic')
80. AnnotationURLCitation(end_index=30986, start_index=30809, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=revealed%20influenza%20virus%20host%20dependency,defects%20in%20virus%20internalization%20and')
81. AnnotationURLCitation(end_index=31151, start_index=30987, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=dissection%20of%20the%20influenza%20virus,influenza%20virus%20entry%20but%20play')
82. AnnotationURLCitation(end_index=31463, start_index=31283, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=siRNA%20depletion%20resulted%20in%20significant,membrane%20protein%20expression%20and%20assembly')
83. AnnotationURLCitation(end_index=32015, start_index=31865, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=leads%20to%20defects%20in%20virus,of%20the%20first%20two%20effects')
84. AnnotationURLCitation(end_index=33027, start_index=32870, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=initiated%20by%20the%20small%20GTPase,We%20found%20that%20Arf1%20occupies')
85. AnnotationURLCitation(end_index=33341, start_index=33186, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
86. AnnotationURLCitation(end_index=33492, start_index=33342, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=match%20at%20L640%20Helix%20a,b%20also%20contacts%20the%20membrane')
87. AnnotationURLCitation(end_index=33855, start_index=33705, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=match%20at%20L640%20Helix%20a,b%20also%20contacts%20the%20membrane')
88. AnnotationURLCitation(end_index=34011, start_index=33856, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
89. AnnotationURLCitation(end_index=34401, start_index=34267, title='Identification of a Fetal De Novo Splice Variant in ARCN1\xa0Associated With Growth and Skeletal Abnormalities - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC12223002/#:~:text=Growth%20and%20Skeletal%20Abnormalities%20,Google')
90. AnnotationURLCitation(end_index=34791, start_index=34624, title='The COPI system: molecular mechanisms and function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/19631211/#:~:text=Transport%20of%20membranes%20and%20proteins,lipids%20during%20COPI%20carrier%20formation')
91. AnnotationURLCitation(end_index=35326, start_index=35193, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=of%20COPI,variants%20in%20COPB2%20cause%20primary')
92. AnnotationURLCitation(end_index=35474, start_index=35327, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=distinctively%20different%2C%20despite%20all%20encoding,related')
93. AnnotationURLCitation(end_index=35848, start_index=35701, title='Expanding the phenotypic spectrum of ARCN1-related syndrome - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9923403/#:~:text=distinctively%20different%2C%20despite%20all%20encoding,related')
94. AnnotationURLCitation(end_index=36370, start_index=36203, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
95. AnnotationURLCitation(end_index=37759, start_index=37618, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Pmp2%20fused%20to%20GFP%20and,based%20signals%20by%20COPI')
96. AnnotationURLCitation(end_index=37910, start_index=37760, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=match%20at%20L640%20Helix%20a,b%20also%20contacts%20the%20membrane')
97. AnnotationURLCitation(end_index=38193, start_index=38003, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=disorder%20characterized%20by%20facial%20dysmorphisms%2C,including%20skeletogenesis%20and%20brain%20growth')
98. AnnotationURLCitation(end_index=38577, start_index=38383, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=Cellular%20homeostasis%20is%20maintained%20by,facial%20dysmorphisms%2C%20severe%20micrognathia%2C%20rhizomelic')
99. AnnotationURLCitation(end_index=38732, start_index=38578, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=the%20cis,of%20its%20impairment%20in%20the')
100. AnnotationURLCitation(end_index=39470, start_index=39320, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=match%20at%20L640%20Helix%20a,b%20also%20contacts%20the%20membrane')
101. AnnotationURLCitation(end_index=39626, start_index=39471, title='9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5482573/#:~:text=Helix%20a%20interacts%20with%20the,b%20also%20contacts%20the%20membrane')
102. AnnotationURLCitation(end_index=39974, start_index=39787, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=dysplasia%20and%20osteogenesis%20imperfect%2C%20caused,collagen%20secretion%20represents%20the%20likely')
103. AnnotationURLCitation(end_index=40160, start_index=39975, title='ARCN1 Mutations Cause a Recognizable Craniofacial Syndrome Due to COPI-Mediated Transport Defects - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC4974084/#:~:text=function%20heterozygous%20mutations%20in%20ARCN1%2C,including%20skeletogenesis%20and%20brain%20growth')
104. AnnotationURLCitation(end_index=40512, start_index=40327, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=neurological%2017%20,the%20mechanisms%20of%20neurodegenerative%20diseases')
105. AnnotationURLCitation(end_index=40693, start_index=40513, title='Mutation in Archain 1, a Subunit of COPI Coatomer Complex, Causes Diluted Coat Color and Purkinje Cell Degeneration | PLOS Genetics', type='url_citation', url='https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1000956#:~:text=whole%20animal%20have%20not%20been,partner%20of%20ARCN1%20in%20yeast')
106. AnnotationURLCitation(end_index=40993, start_index=40852, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=Pmp2%20fused%20to%20GFP%20and,based%20signals%20by%20COPI')
107. AnnotationURLCitation(end_index=41123, start_index=40994, title='Novel cargo-binding site in the β and δ subunits of coatomer - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2064757/#:~:text=and%20%CE%B4,of%20the%20COPI%20trunk%20domain')
108. AnnotationURLCitation(end_index=41413, start_index=41312, title='Architecture of coatomer: molecular characterization of delta-COP and protein interactions within the complex - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2121028/#:~:text=,Google%20Scholar')
109. AnnotationURLCitation(end_index=41515, start_index=41414, title='Delta- and zeta-COP, two coatomer subunits homologous to clathrin-associated proteins, are involved in ER retrieval - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC450095/#:~:text=4,Google%20Scholar')
110. AnnotationURLCitation(end_index=41820, start_index=41653, title='Frontiers | COPZ1: an example of non-oncogene addiction in human tumors', type='url_citation', url='https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1636326/full#:~:text=The%20human%20COPI%20coatomer%20,The%20COPI')
111. AnnotationURLCitation(end_index=42143, start_index=41966, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=revealed%20influenza%20virus%20host%20dependency,defects%20in%20virus%20internalization%20and')
112. AnnotationURLCitation(end_index=42308, start_index=42144, title='Dissecting the Role of COPI Complexes in Influenza Virus Infection - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3571408/#:~:text=dissection%20of%20the%20influenza%20virus,influenza%20virus%20entry%20but%20play')