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Showing STX18UFE1 is a alias.

STX18

Syntaxin-18 · UniProt Q9P2W9

Length
335 aa
Mass
38.7 kDa
Annotated
2026-06-10
38 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

STX18 (yeast Ufe1) is an ER-resident Qa/t-SNARE that drives retrograde vesicular transport from the Golgi to the endoplasmic reticulum (PMID:9214619). It assembles a functional SNARE complex with Sec20, Tip20, and the v-SNARE Sec22, an arrangement confirmed by reciprocal co-precipitation and allele-specific genetic suppression and conserved across fungal species (PMID:9214619, PMID:12471444); this t-SNARE machinery operates as the docking apparatus for Golgi-derived COPI retrograde vesicles together with the Dsl1 tethering complex, while STX18 itself remains an ER-resident protein that does not enter COPII vesicles under normal conditions (PMID:9639310, PMID:21550981). Beyond vesicular fusion, STX18 mediates homotypic ER membrane fusion through direct t-t-SNARE and AAA-ATPase Cdc48p/p97 interactions, a fusion route independent of NSF/Sec18 (PMID:9506516), and its stability is controlled by the SM protein Sly1/SCFD1, which protects it from ERAD-mediated proteasomal degradation (PMID:18007658). In mammals STX18 supports ER-to-Golgi export of large extracellular-matrix cargo such as type II collagen during chondrogenesis and is required for cartilage and bone development, with a homozygous p.Arg10Pro substitution associated with severe osteochondrodysplasia (PMID:27851892, PMID:37718532). STX18 additionally functions outside its canonical transport role: it can be exported in COPII vesicles to autophagosome formation sites during starvation (PMID:26876173), regulates surface trafficking of the MR1 antigen-presenting molecule (PMID:27031111), and acts as a negative regulator of lipophagy by binding ATG14 to block PI3KC3-C1 complex assembly and ATG14-ATG8 interactions—a brake that coronavirus M protein subverts to degrade the antiviral protein Viperin (PMID:38245527).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 1996 Medium

    Established that the STX18 ortholog UFE1 is an essential gene whose sequence ties it to the secretory pathway, motivating its mechanistic characterization.

    Evidence Gene disruption and sequence analysis in S. cerevisiae

    PMID:8929391

    Open questions at the time
    • No molecular function assigned
    • Secretory-pathway role inferred only from sequence similarity
  2. 1997 High

    Defined STX18/Ufe1 as the ER t-SNARE for Golgi-to-ER retrograde transport and identified its core SNARE partners, resolving the directionality and machinery of the pathway.

    Evidence Co-precipitation plus allele-specific multicopy suppressor screen in yeast (Sec20p, Tip20p, Sec22p)

    PMID:9214619

    Open questions at the time
    • Stoichiometry of the SNAREpin not resolved
    • No structural model of the complex
  3. 1998 High

    Showed STX18/Ufe1 also drives homotypic ER membrane fusion through a Cdc48p-dependent, NSF/Sec17-independent route, distinguishing organelle fusion from vesicle traffic.

    Evidence In vitro ER membrane fusion assay with protein interaction and genetic analysis in yeast

    PMID:9506516

    Open questions at the time
    • How Cdc48p substitutes for NSF mechanistically unclear
    • Relationship between fusion and traffic roles of the same t-SNARE not dissected
  4. 1998 Medium

    Linked STX18/Ufe1 function to COPI-mediated recycling of Sec22 and to the Tip20-containing docking complex, situating it in retrograde coat machinery.

    Evidence Reporter assay, immunofluorescence, and synthetic-lethality analysis with COPI components in yeast

    PMID:9580559 PMID:9639310

    Open questions at the time
    • Physical architecture of the docking complex not defined
    • Single-lab genetic evidence
  5. 2003 Medium

    Identified Slt1/Use1 as an additional SNARE partner of Ufe1, refining the composition of the retrograde SNAREpin.

    Evidence Complex assembly and functional knockdown in yeast

    PMID:12893879

    Open questions at the time
    • Fourth SNARE assignment (Sec20) inferred not proven
    • Single-lab evidence
  6. 2007 Medium

    Revealed that STX18/Ufe1 abundance is set by ERAD and selectively protected by the SM protein Sly1, adding a degradative layer of regulation.

    Evidence Protein stability assays across ERAD-component genetic backgrounds in yeast

    PMID:18007658

    Open questions at the time
    • E3 ligase mediating Ufe1 ERAD not identified
    • Mechanism of Sly1 protection structurally undefined
  7. 2011 High

    Reconstituted the Dsl1 tethering complex with the ER SNAREs and established R-SNARE preference (Sec22 over Ykt6), defining the tethering-to-fusion handoff for COPI vesicles.

    Evidence In vitro binding, in vivo co-IP, and COPII vesicle fractionation in yeast

    PMID:21550981

    Open questions at the time
    • Regulatory role of Ykt6 displacement by NSF not functionally defined
    • No structure of the full Dsl1-SNARE assembly
  8. 2016 Medium

    Extended STX18 function to mammalian ER export of large ECM cargo, showing it (with SCFD1) is specifically required for type II collagen transport in chondrocytes.

    Evidence Knockdown in mammalian chondrocytes with collagen II transport readout, supported by zebrafish

    PMID:27851892

    Open questions at the time
    • Whether STX18 acts directly at the export step or via retrograde recycling unresolved
    • Single-lab evidence
  9. 2016 Medium

    Connected STX18/Ufe1 to autophagy by showing starvation-induced COPII export to autophagosome formation sites and an autophagy defect upon loss, broadening its role beyond ER residency.

    Evidence Live imaging, genetic LOF, and sec23-1 COPII-mutant analysis in yeast

    PMID:26876173

    Open questions at the time
    • Identity of non-ER SNARE partners at autophagosomes not defined
    • Mechanism coupling COPII export to autophagosome biogenesis unclear
  10. 2016 Medium

    Implicated STX18 in immune antigen presentation by showing it controls MR1 surface trafficking and MAIT cell recognition of infected cells.

    Evidence shRNA knockdown with surface MR1 quantification and MAIT activation assay in antigen-presenting cells

    PMID:27031111

    Open questions at the time
    • Trafficking step at which STX18 acts on MR1 not mapped
    • Single-lab evidence
  11. 2018 Medium

    Demonstrated viral co-option of STX18/Ufe1, with TBSV p33 binding it to build replication compartments, revealing host-membrane machinery hijacking.

    Evidence Co-IP, cell-free replicase assay, imaging, and depletion in yeast

    PMID:29746582

    Open questions at the time
    • Whether SNARE activity per se or membrane scaffolding is required not separated
    • Single-lab evidence
  12. 2023 Medium

    Established STX18 as required for vertebrate skeletal development in vivo and linked a human variant to osteochondrodysplasia, providing disease relevance.

    Evidence Human variant identification, CRISPR/Cas9 zebrafish LOF, and SNARE/coat expression analysis

    PMID:37718532

    Open questions at the time
    • Causality of p.Arg10Pro not proven by rescue
    • Mechanism linking transport defect to skeletal phenotype indirect
  13. 2024 High

    Uncovered a non-canonical role for STX18 as a lipophagy brake via ATG14 binding, and its subversion by coronavirus M protein to degrade antiviral Viperin.

    Evidence Reciprocal co-IP, siRNA knockdown, lipid droplet degradation, Viperin level and virus production assays

    PMID:38245527

    Open questions at the time
    • Structural basis of STX18-ATG14 competition undefined
    • Whether SNARE/transport activity contributes to lipophagy regulation unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How STX18's canonical SNARE-fusion activity is mechanistically reconciled with its non-canonical autophagy-regulatory and antigen-trafficking functions in mammalian cells remains unresolved.
  • No structure of mammalian STX18 complexes
  • Direct versus indirect contribution to each non-transport role not separated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 3 GO:0060090 molecular adaptor activity 3
Localization
GO:0005783 endoplasmic reticulum 4 GO:0005794 Golgi apparatus 2
Pathway
R-HSA-5653656 Vesicle-mediated transport 3 R-HSA-1266738 Developmental Biology 2 R-HSA-9612973 Autophagy 2 R-HSA-168256 Immune System 1
Complex memberships
Dsl1 tethering complexER t-SNARE complex (Ufe1/Sec20/Use1/Sec22)

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1996 UFE1 (STX18 ortholog in S. cerevisiae) is an essential gene required for both spore germination and vegetative growth, with sequence similarity to SED5 and the coiled-coil region of USO1, suggesting involvement in the secretory pathway. Gene disruption experiments, sequence analysis Current genetics Medium 8929391
1997 Ufe1p (yeast STX18 ortholog) functions as an ER t-SNARE mediating retrograde transport from the Golgi to the ER. It forms a functional SNARE complex with Sec20p, Tip20p, and the v-SNARE Sec22p. A growth-inhibiting mutation in Ufe1p is compensated by a mutation in Sec20p, and SEC22 acts as an allele-specific multicopy suppressor of a temperature-sensitive ufe1 mutation. Co-precipitation, genetic suppressor analysis, allele-specific multicopy suppressor screen The EMBO journal High 9214619
1998 Ufe1p (yeast STX18 ortholog) is required for ER membrane fusion in a process that does not require Sec18p/NSF or Sec17p but instead requires the NSF-related ATPase Cdc48p. Ufe1p acts as a t-SNARE undergoing direct t-t-SNARE and Cdc48p interactions during organelle (ER) membrane fusion, in addition to its role as a t-SNARE for vesicular traffic. In vitro ER membrane fusion assay, protein interaction studies, genetic analysis Cell High 9506516
1998 The v-SNARE Sec22p recycles from the Golgi back to the ER via retrograde COPI vesicles, and this recycling requires functional Ufe1p (yeast STX18 ortholog) as well as Sec20p, Sec21p, and Sec27p. Ufe1-1 mutant cells show mislocalization of Sec22p to Golgi structures rather than ER. Immunofluorescence microscopy, subcellular fractionation, alpha-factor-tagged Sec22 reporter assay in yeast mutants Journal of cell science Medium 9580559
1998 Temperature-sensitive tip20 mutants are synthetic lethal with ufe1-1 and ret2-1 (delta-COP), indicating Tip20p and Ufe1p (yeast STX18 ortholog) function together in ER-Golgi retrograde transport, likely as part of the docking complex for Golgi-derived retrograde transport vesicles. Synthetic lethality / genetic epistasis analysis Yeast (Chichester, England) Medium 9639310
2002 Candida albicans Ufe1p (ortholog of STX18) functionally complements a thermosensitive ufe1 mutation in S. cerevisiae, demonstrating functional conservation of the ER t-SNARE activity across fungal species. CaUfe1p interacts with CaSec20p and CaTip20p as part of an ER-tSNARE complex. Complementation assay, two-hybrid analysis, co-immunoprecipitation Molecular genetics and genomics Medium 12471444
2003 Slt1 (a previously uncharacterized ER-localized SNARE) forms a SNARE complex with Sec22 and the ER syntaxin Ufe1 (yeast STX18 ortholog) and is required for retrograde traffic to the ER. Down-regulation of Slt1 leads to improper secretion of proteins normally resident in the ER. Sec20 likely contributes the fourth SNARE to this SNAREpin. Sequence analysis, localization studies, functional knockdown, complex assembly assay Proceedings of the National Academy of Sciences of the United States of America Medium 12893879
2007 Yeast Ufe1 (STX18 ortholog) is subject to ERAD-like degradation by the ubiquitin-proteasome system, and is protected from this degradation by binding to the SM protein Sly1. This SM-protein-controlled stabilization is specific to Ufe1 and does not apply to the Golgi Qa-SNARE Sed5, despite both being Sly1 partners. Protein stability assays, genetic manipulation of ERAD components, interaction studies EMBO reports Medium 18007658
2011 The Dsl1 tethering complex (Dsl1, Dsl3/Sec39, Tip20) forms a stable complex with the ER SNAREs Ufe1, Use1, and Sec20 to mediate fusion of COPI vesicles with the ER. Among R-SNAREs, Sec22 is preferred over Ykt6 in the Dsl-SNARE complex. NSF/Sec18 can displace Ykt6 but not Sec22, suggesting a regulatory role for Ykt6. Ufe1 and Sec20 are ER-resident proteins that do not enter COPII vesicles. In vitro binding assays, in vivo co-immunoprecipitation, subcellular fractionation (COPII vesicle analysis) The Journal of biological chemistry High 21550981
2016 During starvation in yeast, Ufe1 (STX18 ortholog) is increasingly exported from the ER in specific COPII vesicles (dependent on Sec23) and targeted to autophagosome formation sites containing Atg8 and Atg9. Ufe1 interacts with non-ER SNARE proteins implicated in autophagosome formation. Loss of Ufe1 function impairs autophagy, resulting in fewer and smaller autophagosomes. Fluorescence microscopy (co-localization with autophagy markers), genetic loss-of-function, COPII mutant analysis (sec23-1), starvation sensitivity assay Cell reports Medium 26876173
2016 STX18 (human) is required for ER to Golgi transport of type II collagen during chondrogenesis. Loss of STX18 or its partner SCFD1 (SLY1) severely impairs transport of type II collagen in mammalian chondrocytes, establishing a specific ER export pathway for large ECM proteins during chondrogenesis. Loss-of-function (knockdown) in mammalian chondrocytes, co-localization/transport assay for type II collagen Developmental biology Medium 27851892
2016 STX18 knockdown in antigen-presenting cells decreases surface translocation of MR1 and impairs MR1-dependent MAIT cell recognition of Mycobacterium tuberculosis-infected cells, indicating STX18 regulates MR1 trafficking and loading of intracellular mycobacterially-derived ligands. Lentiviral shRNA screen, surface MR1 quantification, MAIT cell activation assay PLoS pathogens Medium 27031111
2018 The ER-resident SNARE Ufe1 (STX18 ortholog) is co-opted by Tomato bushy stunt virus (TBSV) into the viral replication compartment. The viral p33 replication protein physically interacts with both Ufe1p and Use1p, and depletion of Ufe1 causes mislocalization of the p33 protein to the ER membrane, reduces viral RNA accumulation, and impairs formation of membrane contact sites, sterol enrichment at replication sites, and recruitment of pro-viral host factors. Co-immunoprecipitation (p33-Ufe1 interaction), cell-free replicase assay, fluorescence microscopy (localization of p33), dominant-negative overexpression, genetic depletion of Ufe1 PLoS pathogens Medium 29746582
2023 STX18 is required for cartilage and bone development in vivo. A homozygous p.Arg10Pro substitution in STX18 is associated with severe osteochondrodysplasia in a human fetus. CRISPR/Cas9-mediated Stx18 deficiency in zebrafish causes defects in cartilage and bone development. Stx18 deficiency is accompanied by increased expression of multiple SNARE complex components (Ufe1 complex) and COPI/COPII proteins, suggesting impairment of both anterograde and retrograde vesicular transport. Human genetics (homozygous variant identification), CRISPR/Cas9 zebrafish loss-of-function, expression analysis of SNARE and coat proteins Journal of bone and mineral research Medium 37718532
2024 STX18 acts as a negative regulator of lipophagy by binding ATG14, disrupting ATG14 interactions with ATG8-family members and subverting PI3KC3-C1 complex formation. Knockdown of STX18 activates ATG14-dependent lipophagy, leading to degradation of lipid droplet-associated anti-viral protein Viperin (RSAD2). Coronavirus M protein binds STX18 and disrupts the STX18-ATG14 interaction to induce lipophagy and degrade Viperin, facilitating virus production. Co-immunoprecipitation (STX18-ATG14 interaction), siRNA knockdown, lipid droplet degradation assay, Viperin/RSAD2 protein level measurement, virus production assay Nature communications High 38245527

Source papers

Stage 0 corpus · 38 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1998 Organelle membrane fusion: a novel function for the syntaxin homolog Ufe1p in ER membrane fusion. Cell 134 9506516
2013 Genome-wide association study of multiple congenital heart disease phenotypes identifies a susceptibility locus for atrial septal defect at chromosome 4p16. Nature genetics 120 23708191
1997 A novel SNARE complex implicated in vesicle fusion with the endoplasmic reticulum. The EMBO journal 119 9214619
2003 Two-hybrid search for proteins that interact with Sad1 and Kms1, two membrane-bound components of the spindle pole body in fission yeast. Molecular genetics and genomics : MGG 89 14655046
2003 A SNARE required for retrograde transport to the endoplasmic reticulum. Proceedings of the National Academy of Sciences of the United States of America 87 12893879
2016 Endosomal MR1 Trafficking Plays a Key Role in Presentation of Mycobacterium tuberculosis Ligands to MAIT Cells. PLoS pathogens 73 27031111
2000 Enhancement of the thermostability and hydrolytic activity of xylanase by random gene shuffling. The Biochemical journal 51 10880366
2016 An ER-Localized SNARE Protein Is Exported in Specific COPII Vesicles for Autophagosome Biogenesis. Cell reports 50 26876173
2024 ATG14 targets lipid droplets and acts as an autophagic receptor for syntaxin18-regulated lipid droplet turnover. Nature communications 48 38245527
1998 Recycling of the yeast v-SNARE Sec22p involves COPI-proteins and the ER transmembrane proteins Ufe1p and Sec20p. Journal of cell science 48 9580559
2011 The Dsl1 protein tethering complex is a resident endoplasmic reticulum complex, which interacts with five soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptors (SNAREs): implications for fusion and fusion regulation. The Journal of biological chemistry 43 21550981
2018 Assembly-hub function of ER-localized SNARE proteins in biogenesis of tombusvirus replication compartment. PLoS pathogens 35 29746582
2016 The Sec domain protein Scfd1 facilitates trafficking of ECM components during chondrogenesis. Developmental biology 35 27851892
2021 DNA Methylation Changes Associated With Type 2 Diabetes and Diabetic Kidney Disease in an East Asian Population. The Journal of clinical endocrinology and metabolism 30 34214161
2020 Co-opted Cellular Sac1 Lipid Phosphatase and PI(4)P Phosphoinositide Are Key Host Factors during the Biogenesis of the Tombusvirus Replication Compartment. Journal of virology 28 32269127
1998 The Saccharomyces cerevisiae early secretion mutant tip20 is synthetic lethal with mutants in yeast coatomer and the SNARE proteins Sec22p and Ufe1p. Yeast (Chichester, England) 24 9639310
2020 Pilot Study to Establish a Novel Five-Gene Biomarker Panel for Predicting Lymph Node Metastasis in Patients With Early Stage Endometrial Cancer. Frontiers in oncology 21 32039004
2008 Effective stimulation of growth in MCF-7 human breast cancer cells by inhibition of syntaxin18 by external guide sequence and ribonuclease P. Cancer letters 20 18722709
2021 The Dissection of SNAREs Reveals Key Factors for Vesicular Trafficking to the Endosome-like Compartment and Apicoplast via the Secretory System in Toxoplasma gondii. mBio 19 34340555
2007 SM-protein-controlled ER-associated degradation discriminates between different SNAREs. EMBO reports 15 18007658
2016 Serum Autoantibodies in Chronic Prostate Inflammation in Prostate Cancer Patients. PloS one 14 26863016
2016 Exploring the neural mechanisms of finasteride: a proteomic analysis in the nucleus accumbens. Psychoneuroendocrinology 12 27750143
2024 ATG14 and STX18: gatekeepers of lipid droplet degradation and the implications for disease modulation. Autophagy 11 38735055
2024 Coronavirus hijacks STX18-ATG14 axis-regulated lipophagy to evade an anti-viral effect. Autophagy 10 38477940
2016 RINT1 functions as a multitasking protein at the crossroads between genomic stability, ER homeostasis, and autophagy. Autophagy 10 27367497
1997 The sequence of a 54.7 kb fragment of yeast chromosome XV reveals the presence of two tRNAs and 24 new open reading frames. Yeast (Chichester, England) 7 9133743
2019 Association between the 4p16 genomic locus and different types of congenital heart disease: results from adult survivors in the UK Biobank. Scientific reports 6 31712678
2016 Characterization of soluble N-ethylmaleimide-sensitive factor attachment protein receptor gene STX18 variations for possible roles in congenital heart diseases. Gene 6 27816473
2022 Novel classification and risk model based on ferroptosis-related lncRNAs to predict oncologic outcomes for gastric cancer patients. Journal of biochemical and molecular toxicology 5 35315178
2002 Sec20p-interacting proteins (Tip20p, Ufe1p) in the retrograde secretory pathway of the fungal pathogen Candida albicans. Molecular genetics and genomics : MGG 4 12471444
2023 Syntaxin 18 Defects in Human and Zebrafish Unravel Key Roles in Early Cartilage and Bone Development. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 3 37718532
1996 Molecular analysis of UFE1, a Saccharomyces cerevisiae gene essential for spore formation and vegetative growth. Current genetics 3 8929391
2022 Innovative computational approaches shed light on genetic mechanisms underlying cognitive impairment among children born extremely preterm. Journal of neurodevelopmental disorders 2 35240980
2022 In silico analysis of the predicted protein-protein interaction of syntaxin-18, a putative receptor of Peregrinus maidis Ashmead (Hemiptera: Delphacidae) with Maize mosaic virus glycoprotein. Journal of biomolecular structure & dynamics 2 35377265
2021 A novel RNA-mediated mechanism causing down-regulation of insulating promoter interactions in human embryonic stem cells. Scientific reports 2 34853328
2025 Genetic Variants Associated With Congenital Heart Disease: A Meta-Analysis of Ethnicity and Subtype-Specific Susceptibility. Circulation. Genomic and precision medicine 1 40859829
2022 Data on cardiac lncRNA STX18-AS1 expression in developing human hearts and function during in vitro hESC-cardiomyocyte differentiation. Data in brief 1 36533287
2025 A Pilot Genome-Wide Association Study of Malignant Transformation of Oral Verrucous Hyperplasia. Oral diseases 0 40698521

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