Affinage

SCYL1

N-terminal kinase-like protein · UniProt Q96KG9

Length
808 aa
Mass
89.6 kDa
Annotated
2026-06-10
36 papers in source corpus 13 papers cited in narrative 13 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SCYL1 is a multifunctional scaffolding pseudokinase that operates principally at the ERGIC/cis-Golgi interface to organize COPI-mediated retrograde membrane trafficking (PMID:18556652, PMID:24481816). It binds the coatomer through a C-terminal RKXX-COO⁻ motif that engages the appendage domain of γ2-COP (COPG2), and through a distinct site selectively links class II Arfs (notably Arf4) to γ2-bearing COPI subcomplexes, oligomerizing via central HEAT repeats; disruption of this scaffolding tubulates the ERGIC and cis-Golgi and enlarges the Golgi, while SCYL1 loss impairs retrograde transport of the KDEL receptor without affecting anterograde traffic (PMID:18556652, PMID:24481816, PMID:20209057). This Golgi-organizing activity is controlled by post-translational regulation: mTORC1 phosphorylates SCYL1 on Ser754 to retain it at the Golgi, and dephosphorylation—promoted by the phosphatase CTDSPL2—displaces SCYL1 to endosomes, enlarging the Golgi and increasing extracellular vesicle secretion (PMID:35948564, PMID:42041204), whereas PRMT1-mediated arginine methylation at the γ2-COP-binding site is required for the SCYL1–γ2-COP interaction, normal Golgi morphology, and neurite outgrowth (PMID:32583741). Beyond trafficking, SCYL1 acts as a cytoplasmic component of the nuclear tRNA export machinery, binding tRNA and forming a quaternary complex with exportin-t and RanGTP at the nuclear pore (PMID:20505071), and serves as a conserved positive regulator of Slo2/Slack potassium channel open probability (PMID:32314960). In the nervous system SCYL1 maintains TDP-43 proteostasis cell-autonomously in motor neurons, and its loss causes TDP-43 and ubiquilin-2 cytoplasmic inclusions, progressive motor neuron disease, and cerebellar/Purkinje degeneration (PMID:23175812, PMID:17571074, PMID:29437892). SCYL1 deficiency also drives ER distension, procollagen-I accumulation, and ER stress-associated cell death in secretory cells, accounting for the neurodegenerative and hepatic features of CALFAN syndrome (PMID:41063534).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2007 Medium

    Establishing a physiological requirement for SCYL1, this work showed that loss of Scyl1 causes a defined neurodegenerative phenotype, placing the gene in CNS maintenance before any molecular mechanism was known.

    Evidence Genetic mapping of the mdf mouse mutant with histopathology and immunolocalization

    PMID:17571074

    Open questions at the time
    • No molecular function assigned at this stage
    • Mechanism linking SCYL1 loss to Purkinje/optic degeneration unresolved
  2. 2008 High

    Answered what SCYL1 does molecularly by identifying it as a coatomer-binding protein that selectively governs COPI retrograde trafficking, defining its core membrane-traffic role.

    Evidence Mass spectrometry binding screen, reciprocal Co-IP with βCOP, RNAi with KDEL-receptor retrograde vs. anterograde trafficking assay

    PMID:18556652

    Open questions at the time
    • Precise COPI subunit contacts not yet mapped
    • Role of Arf isoforms unaddressed
  3. 2010 High

    Two studies refined SCYL1's Golgi role: defining its requirement for Golgi ultrastructure and golgin-dependent localization, and revealing an independent function in nuclear tRNA export.

    Evidence RNAi with EM morphometry and FTCD Co-IP; tRNA export rescue, saturable tRNA binding, co-purification and in vitro quaternary complex reconstitution with exportin-t/RanGTP

    PMID:20209057 PMID:20505071

    Open questions at the time
    • How one protein partitions between Golgi and nuclear-pore functions unresolved
    • Stoichiometry of the tRNA export complex in vivo unknown
  4. 2012 High

    Determined that SCYL1 acts cell-autonomously in neurons to maintain TDP-43 proteostasis, mechanistically connecting its loss to motor neuron disease.

    Evidence Neural- vs. muscle-specific conditional knockout mice with TDP-43 and ubiquilin-2 immunofluorescence

    PMID:23175812

    Open questions at the time
    • Molecular link between SCYL1 trafficking function and TDP-43 mislocalization not defined
  5. 2014 High

    Resolved the molecular architecture of SCYL1's scaffolding function, showing it bridges class II Arfs to γ2-COP via discrete domains and controls ERGIC/cis-Golgi membrane shape.

    Evidence Co-IP, domain mapping/mutagenesis, direct binding assays, fluorescence imaging of ERGIC/Golgi tubulation

    PMID:24481816

    Open questions at the time
    • Functional consequence of Arf4 selectivity for specific cargo not established
    • No structural model of the SCYL1–γ2-COP–Arf assembly
  6. 2017 Medium

    Refuted a prior model that SCYL1 mediates REST degradation, removing a putative function from the gene's repertoire.

    Evidence Scyl1−/− MEFs, CRISPR KO HEK293T, and RNAi across cell lines with REST western blots for levels and turnover

    PMID:28570664

    Open questions at the time
    • Negative result; does not exclude context-specific regulation
  7. 2018 Medium

    Genetic epistasis with Scyl3 showed overlapping roles in TDP-43 proteostasis, indicating functional redundancy within the SCYL family for motor neuron viability.

    Evidence Scyl1/Scyl3 double-knockout mice with behavior, histopathology, and TDP-43 immunofluorescence

    PMID:29437892

    Open questions at the time
    • Shared molecular substrate of SCYL1/SCYL3 not identified
    • Whether redundancy applies to trafficking functions untested
  8. 2020 High

    Two studies expanded SCYL1's regulation and reach: PRMT1 arginine methylation gates the γ2-COP interaction and neurite outgrowth, and SCYL1 was identified as a conserved positive regulator of Slo2/Slack channel open probability.

    Evidence PRMT1 inhibition, methylation-deficient SCYL1 rescue, neurite assays; C. elegans scyl-1 KO with single-channel patch-clamp and heterologous human SCYL1/Slo2.2 reconstitution

    PMID:32314960 PMID:32583741

    Open questions at the time
    • Mechanism by which SCYL1 modulates channel gating unknown
    • Relationship between channel regulation and trafficking role unclear
  9. 2022 High

    Identified mTORC1-dependent Ser754 phosphorylation as the switch retaining SCYL1 at the Golgi, linking nutrient signaling to organelle morphology and vesicle secretion.

    Evidence mTORC1 inhibitor treatment, Ser754Ala phosphomutant, organelle imaging and nanoparticle tracking of extracellular vesicles

    PMID:35948564

    Open questions at the time
    • Direct kinase-substrate contact not biochemically resolved
    • Endosomal function of displaced SCYL1 undefined
  10. 2025 Medium

    Defined the cellular basis of CALFAN syndrome pathology, showing SCYL1 loss causes ER stress and cell death rather than a direct procollagen trafficking block.

    Evidence CALFAN patient-derived and KO fibroblasts with procollagen-I/ER imaging, ER stress markers, and viability assays at febrile temperature

    PMID:41063534

    Open questions at the time
    • Why ER stress arises despite intact trafficking unresolved
    • Single-lab study
  11. 2026 Medium

    Placed the phosphatase CTDSPL2 opposite mTORC1 on the Ser754 switch, connecting SCYL1 regulation to extracellular vesicle secretion in drug-resistant cancer.

    Evidence Co-IP, CTDSPL2 knockdown, SCYL1 Ser754Ala phosphomutant, nanoparticle tracking and in vivo tumorigenesis

    PMID:42041204

    Open questions at the time
    • Direct dephosphorylation of Ser754 by CTDSPL2 not shown biochemically
    • Generality beyond breast cancer untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • How SCYL1's distinct molecular activities—COPI scaffolding, tRNA export, and Slo2 channel regulation—are integrated within a single protein, and how each contributes to TDP-43 proteostasis and CALFAN disease, remains unresolved.
  • No structural model unifying the scaffold/export/channel functions
  • Mechanistic bridge from trafficking defects to TDP-43 mislocalization undefined
  • Substrate or cargo selectivity in vivo not mapped

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2 GO:0003723 RNA binding 1 GO:0098772 molecular function regulator activity 1
Localization
GO:0005794 Golgi apparatus 4 GO:0005783 endoplasmic reticulum 2 GO:0005829 cytosol 1
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-5653656 Vesicle-mediated transport 2 R-HSA-8953854 Metabolism of RNA 1
Complex memberships
COPI coatomer (γ2-COP/COPG2 subcomplex)exportin-t–tRNA–RanGTP tRNA export complex

Evidence

Reading pass · 13 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2008 SCYL1 binds COPI coat components (coatomer) via a C-terminal RKLD-COO⁻ sequence analogous to the KKXX-COO⁻ ER-retrieval motif, co-immunoprecipitates with βCOP from brain lysates, and localizes to the ERGIC and cis-Golgi in an Arf1-independent manner. RNAi-mediated knockdown of SCYL1 disrupts COPI-mediated retrograde trafficking of the KDEL receptor to the ER without affecting anterograde traffic. Mass spectrometry-based binding screen, pull-down assays, co-immunoprecipitation, RNAi knockdown with trafficking assay (KDEL receptor retrograde vs. anterograde) The Journal of biological chemistry High 18556652
2007 Loss-of-function mutation in Scyl1 causes the murine mdf (muscle-deficient) neurodegenerative phenotype comprising cerebellar atrophy, Purkinje cell loss, and optic nerve atrophy. SCYL1 is enriched at CNS synapses and neuromuscular junctions. Genetic mapping of mdf mouse mutant, histopathology, immunolocalization EMBO reports Medium 17571074
2010 SCYL1 knockdown increases Golgi surface area and volume and disrupts orderly Golgi ultrastructure (increased cisternal luminal width) without altering Golgi polarity or cisternae number. SCYL1 Golgi localization depends on the golgin p115 network. SCYL1 interacts with the cis-Golgi-associated protein 58K/FTCD. RNAi knockdown, fluorescence and electron microscopy, co-immunoprecipitation (SCYL1 with FTCD) PloS one Medium 20209057
2010 SCYL1 is a cytoplasmic component of the nuclear tRNA export machinery. It binds tRNA saturably, associates with the nuclear pore complex through interaction with Nup98, co-purifies with exportin-t, exportin-5, RanGTPase, and eEF-1A, interacts directly with exportin-t and RanGTP (but not RanGDP) in vitro, and forms a quaternary complex with exportin-t, tRNA, and RanGTP in vitro. Overexpression of SCYL1 restores export of a nuclear export-defective tRNA mutant. tRNA export rescue assay in COS-7 cells, saturable tRNA binding assay, co-purification, in vitro binding assays (direct interaction with exportin-t, RanGTP), quaternary complex reconstitution Molecular biology of the cell High 20505071
2012 Neural-specific (but not skeletal muscle-specific) deletion of Scyl1 causes progressive motor neuron disease with loss of lower motor neurons, axonal degeneration, and mislocalization/accumulation of TDP-43 and ubiquilin-2 into cytoplasmic inclusions within lower motor neurons, indicating SCYL1 acts cell-autonomously in neurons to maintain TDP-43 proteostasis. Conditional knockout mice (neural-specific and muscle-specific Cre), histopathology, immunofluorescence for TDP-43 and ubiquilin-2 localization The Journal of neuroscience High 23175812
2014 SCYL1 oligomerizes through centrally located HEAT repeats, uses its C-terminal RKXX-COO⁻ motif to bind directly to the appendage domain of γ2-COP (COPG2), and through a distinct site selectively interacts with class II Arfs (notably Arf4), thereby scaffolding class II Arfs to γ2-bearing COPI subcomplexes. Disruption of this scaffolding function causes tubulation of the ERGIC and cis-Golgi. Co-immunoprecipitation, direct binding assays, domain mapping/mutagenesis, fluorescence microscopy of ERGIC/Golgi morphology upon loss of scaffolding Journal of cell science High 24481816
2018 Loss of Scyl3 alone has no effect in mice, but combined deletion of Scyl1 and Scyl3 accelerates onset of motor neuron disease compared with Scyl1 deficiency alone. Disease onset correlated with earlier TDP-43 mislocalization in spinal motor neurons, indicating overlapping roles for SCYL1 and SCYL3 in TDP-43 proteostasis and motor neuron viability. Scyl1/Scyl3 double-knockout mice, behavioral assessment, histopathology, immunofluorescence for TDP-43 The Journal of neuroscience Medium 29437892
2020 SCYL1 arginine methylation by PRMT1 at the γ2-COP-binding site is required for the SCYL1–γ2-COP interaction and normal Golgi morphology. PRMT1 co-localizes with SCYL1 in the Golgi fraction. Inhibition of PRMT1 or expression of arginine methylation-defective SCYL1 suppresses axon outgrowth and dendrite complexity via abnormal Golgi morphology. PRMT1 inhibition, co-localization by fractionation, siRNA knockdown of SCYL1 with rescue by wild-type vs. methylation-deficient mutant SCYL1, neurite outgrowth assays Molecular biology of the cell Medium 32583741
2020 In C. elegans, the SCYL1 orthologue SCYL-1 physically interacts with the Slo2 potassium channel (SLO-2) in neurons and increases single-channel open probability (~50% reduction in scyl-1 knockout). Correspondingly, human SCYL1 doubles the open probability of human Slo2.2/Slack in a heterologous expression system, indicating an evolutionarily conserved role as a positive regulator of Slo2 channel activity. C. elegans genetics (scyl-1 knockout), single-channel patch-clamp electrophysiology, heterologous expression of human SCYL1 with Slo2.2/Slack, physical interaction assay eLife High 32314960
2022 mTORC1 phosphorylates SCYL1 on Ser754 under growth conditions, maintaining SCYL1 at the Golgi. Upon mTORC1 inhibition, dephosphorylation of Ser754 causes SCYL1 displacement to endosomes, leading to Golgi enlargement, redistribution of early and late endosomes, and increased extracellular vesicle secretion. mTORC1 inhibitor treatment, phosphomutant SCYL1 (Ser754Ala), live cell imaging and organelle morphology quantification, nanoparticle tracking for extracellular vesicles Nature communications High 35948564
2025 SCYL1-deficient fibroblasts (CALFAN patient-derived and SCYL1 knockout) accumulate procollagen type I in the ER, display ER distension, and show elevated ER stress and increased cell death, particularly at elevated temperatures mimicking febrile conditions. No procollagen-I trafficking defect was detected, suggesting the primary pathological mechanism is ER stress rather than direct trafficking impairment. Patient and KO fibroblasts, immunofluorescence/EM for procollagen-I and ER morphology, ER stress markers, cell viability assays at elevated temperature Disease models & mechanisms Medium 41063534
2026 CTDSPL2 binds SCYL1 (demonstrated by Co-IP) and acts as a phosphatase that suppresses SCYL1 phosphorylation at Ser754. In PTX-resistant breast cancer cells, CTDSPL2 knockdown increases SCYL1 Ser754 phosphorylation; mutating Ser754 to alanine blocks this effect, linking CTDSPL2 to mTORC1-SCYL1 axis and extracellular vesicle secretion. Co-immunoprecipitation, CTDSPL2 knockdown, SCYL1 Ser754Ala phosphomutant, nanoparticle tracking for extracellular vesicles, in vivo tumorigenesis assay Cell cycle Medium 42041204
2017 SCYL1 does not regulate REST protein levels or turnover: REST steady-state levels and degradation were identical in Scyl1+/+ vs. Scyl1−/− MEFs, CRISPR-Cas9 SCYL1 knockout HEK293T cells, and RNAi-depleted HEK293T or MDA-MB-231 cells. This is a negative result refuting a prior claim that SCYL1 mediates REST degradation. Scyl1−/− MEFs, CRISPR-Cas9 KO in HEK293T, RNAi in HEK293T and MDA-MB-231; western blot for REST levels and turnover PloS one Medium 28570664

Source papers

Stage 0 corpus · 36 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2008 Scyl1, mutated in a recessive form of spinocerebellar neurodegeneration, regulates COPI-mediated retrograde traffic. The Journal of biological chemistry 78 18556652
2007 Mutation in the Scyl1 gene encoding amino-terminal kinase-like protein causes a recessive form of spinocerebellar neurodegeneration. EMBO reports 59 17571074
2010 Scyl1 regulates Golgi morphology. PloS one 50 20209057
2014 Scyl1 scaffolds class II Arfs to specific subcomplexes of coatomer through the γ-COP appendage domain. Journal of cell science 40 24481816
2012 An early onset progressive motor neuron disorder in Scyl1-deficient mice is associated with mislocalization of TDP-43. The Journal of neuroscience : the official journal of the Society for Neuroscience 35 23175812
2019 Pathogenesis and biomarkers of natural killer T cell lymphoma (NKTL). Journal of hematology & oncology 34 30876435
2010 Scyl1 facilitates nuclear tRNA export in mammalian cells by acting at the nuclear pore complex. Molecular biology of the cell 30 20505071
2016 miRNA expression profiling of Epstein-Barr virus-associated NKTL cell lines by Illumina deep sequencing. FEBS open bio 26 27239439
2022 mTORC1 controls Golgi architecture and vesicle secretion by phosphorylation of SCYL1. Nature communications 25 35948564
2018 Variant in SCYL1 gene causes aberrant splicing in a family with cerebellar ataxia, recurrent episodes of liver failure, and growth retardation. European journal of human genetics : EJHG 24 30258122
2018 Overlapping Role of SCYL1 and SCYL3 in Maintaining Motor Neuron Viability. The Journal of neuroscience : the official journal of the Society for Neuroscience 22 29437892
2024 Disorders of vesicular trafficking presenting with recurrent acute liver failure: NBAS, RINT1, and SCYL1 deficiency. Journal of inherited metabolic disease 20 38279772
2020 SCYL1 arginine methylation by PRMT1 is essential for neurite outgrowth via Golgi morphogenesis. Molecular biology of the cell 19 32583741
2019 Recurrent acute liver failure associated with novel SCYL1 mutation: A case report. World journal of clinical cases 18 30842961
2010 Overexpression of SCYL1-BP1 stabilizes functional p53 by suppressing MDM2-mediated ubiquitination. FEBS letters 17 20849854
2012 SCYL1 binding protein 1 promotes the ubiquitin-dependent degradation of Pirh2 and has tumor-suppressive function in the development of hepatocellular carcinoma. Carcinogenesis 16 22570270
2010 A newly identified Pirh2 substrate SCYL1-BP1 can bind to MDM2 and accelerate MDM2 self-ubiquitination. FEBS letters 15 20598683
2009 Localization of TEIF in the centrosome and its functional association with centrosome amplification in DNA damage, telomere dysfunction and human cancers. Oncogene 12 19198626
2005 Transcriptional upregulation of DNA polymerase beta by TEIF. Biochemical and biophysical research communications 11 15963946
2019 Generation of an induced pluripotent stem cell (iPSC) line, DHMCi005-A, from a patient with CALFAN syndrome due to mutations in SCYL1. Stem cell research 8 30959346
2017 SCYL1 does not regulate REST expression and turnover. PloS one 8 28570664
2016 Fission Yeast SCYL1/2 Homologue Ppk32: A Novel Regulator of TOR Signalling That Governs Survival during Brefeldin A Induced Stress to Protein Trafficking. PLoS genetics 8 27191590
2021 SCYL1 disease and liver transplantation diagnosed by reanalysis of exome sequencing and deletion/duplication analysis of SCYL1. American journal of medical genetics. Part A 7 33442927
2019 The factors associated with the early diagnosis of nasal NK/T-cell lymphoma with prominent ocular symptoms and general nasal NKTL. American journal of otolaryngology 7 30717991
2016 SCYL1-BP1 affects cell cycle arrest in human hepatocellular carcinoma cells via Cyclin F and RRM2. Anti-cancer agents in medicinal chemistry 7 25980818
2009 [Expression of TEIF protein in colorectal tumors and its correlation with centrosome abnormality]. Ai zheng = Aizheng = Chinese journal of cancer 7 19958622
2020 Slo2 potassium channel function depends on RNA editing-regulated expression of a SCYL1 protein. eLife 6 32314960
2022 Overexpression of SCYL1 Is Associated with Progression of Breast Cancer. Current oncology (Toronto, Ont.) 4 36290821
2014 TEIF associated centrosome activity is regulated by EGF/PI3K/Akt signaling. Biochimica et biophysica acta 4 24769208
2013 SCY1-like 1 binding protein 1 (SCYL1-bp1) interacts with p53-induced RING H2 protein (Pirh2) after traumatic brain injury in rats. Journal of molecular histology 3 23479292
2024 SCYL1-mediated regulation of the mTORC1 signaling pathway inhibits autophagy and promotes gastric cancer metastasis. Journal of cancer research and clinical oncology 2 39394539
2014 Transcriptional profiling and dynamical regulation analysis identify potential kernel target genes of SCYL1-BP1 in HEK293T cells. Molecules and cells 2 25234469
2006 [Expression of TEIF protein in soft tissue tumors and its significance]. Zhonghua bing li xue za zhi = Chinese journal of pathology 2 17374207
2026 CTDSPL2 facilitates resistance to paclitaxel in breast cancer cells by suppressing SCYL1 phosphorylation. Cell cycle (Georgetown, Tex.) 0 42041204
2026 Recurrent Liver Failure due to SCYL1 Deficiency: A Report of 2 Cases and a Review of the Literature. Journal of clinical and experimental hepatology 0 42256251
2025 SCYL1 deficiency in CALFAN syndrome is associated with ER stress and cell death. Disease models & mechanisms 0 41063534

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