ERLIN1 Protein (Erlin-1)
Overview <table class="infobox infobox-protein">
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ERLIN1 Protein (Erlin-1)
Overview <table class="infobox infobox-protein">
Erlin-1 (ERLIN1), also known as SPFH1 (Stomatin/Prohibitin/Flotillin/HflC/K), is an ER-resident protein that plays critical roles in lipid raft dynamics, cholesterol metabolism, and protein quality control. It forms characteristic ring-like structures in the ER membrane and is involved in the ER-associated degradation (ERAD) of misfolded proteins. Mutations in ERLIN1 are associated with hereditary spastic paraplegia (HSP), and the protein has been implicated in ALS and other neurodegenerative disorders.
Structure
Primary Structure
Length: 299 amino acidsMolecular Weight: ~33,700 DaType: Type III ER membrane protein (both N- and C-termini in cytoplasm)Domain Architecture
SPFH Domain (Residues 22-184): Highly conserved stomatin/prohibitin/flotillin/HflC/K domain
Forms oligomeric complexes
Mediates protein-protein interactions
Transmembrane Regions: Two hydrophobic segments
Anchors protein in ER membrane
C-terminal Region (Residues 185-299): Lipid-binding capacity
Oligomerization interface
Oligomeric Structure
Ring-like Complexes: ERLIN1/2 form ~400 kDa ring structuresHetero-oligomers: ERLIN1 typically forms heterooligomers with ERLIN2Stoichiometry: ~12-14 subunits per ringKey Mutations
R67X: Hereditary spastic paraplegia (HSP), truncationG51R: HSP, loss of functionA145T: ALS, reduced functionNormal Function
ER Lipid Raft Degradation (ERLD) ERLIN1 is a key component of the ERAD machinery: [@huber2022]
Cholesterol Sensing: Detects cholesterol excess in ER membranesLipid Raft Turnover: Regulates lipid raft compositionProtein Quality Control: Targets misfolded proteins for degradationSterol-Regulated Degradation
SREBP Cleavage: Regulates SREBP (sterol regulatory element-binding protein)HMG-CoA Reductase: Degrades HMGCR under high cholesterolACAT2: Regulates acyl-CoA:cholesterol acyltransferaseProtein Quality Control
ERAD Substrate Recognition: Identifies misfolded proteinsVCP/p97 Recruitment: Recruits ubiquitin-proteasome machineryChannel Formation: May form retro-translocation channelsAdditional Functions
Cytoskeletal Organization: Links to actin cytoskeletonCell Signaling: Modulates various signaling pathwaysMembrane Protein Trafficking: Regulates membrane protein levelsRole in Neurodegeneration
Hereditary Spastic Paraplegia (HSP)
Autosomal Recessive inheritancePrimary Function Loss: Mutations cause loss of ERLIN1 functionER Stress: Impaired lipid homeostasis triggers ER stressCorticospinal Tract Degeneration: Upper motor neuron lossAmyotrophic Lateral Sclerosis (ALS)
Aggregate Recruitment: Found in [TDP-43 protein](/mechanisms/tdp-43-proteinopathy) aggregatesER Stress: Contributes to chronic ER stressLipid Dysregulation: Alters membrane lipid compositionMotor Neuron Vulnerability: Impaired protein quality controlAlzheimer's Disease
Cholesterol Metabolism: Links to lipid hypothesis of ADAmyloid Processing: May influence [APP](/entities/app-protein) processingNeuronal ER Stress: Contributes to AD pathologyParkinson's Disease
[α-Synuclein](/proteins/alpha-synuclein) Interaction: May affect α-synuclein clearanceER-Mitochondria Contacts: Modulates MAM functionDopaminergic Neuron Survival: Critical for neuronal healthMechanism of Neurodegeneration
Loss of Function: Mutations impair lipid homeostasisER Stress: Chronic [unfolded protein response](/entities/unfolded-protein-response)Lipid Raft Abnormalities: Altered membrane compositionProtein Aggregate Susceptibility: Impaired clearanceMitochondrial Dysfunction: Altered calcium handling
Therapeutic Targeting
Small Molecule Approaches
Gene Therapy
AAV-ERLIN1: Gene replacement for HSPCRISPR Editing: Correct ERLIN1 mutationssiRNA Knockdown: For gain-of-function studiesProtein-Based Therapies
Recombinant ERLIN1: Protein replacementPeptide Mimetics: Functional ERLIN1 fragmentsProtein Interactions
Cross-Links
[ERLIN1 Gene](/genes/erlin1)
[Hereditary Spastic Paraplegia](/diseases/hereditary-spastic-paraplegia)
[Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
[ER Stress Pathway](/mechanisms/er-stress-pathway)
[Cholesterol Metabolism in Neurodegeneration](/mechanisms/sphingolipid-metabolism)
See Also
[Hereditary Spastic Paraplegia](/diseases/hereditary-spastic-paraplegia)
[Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
[ER Stress Pathway](/mechanisms/er-stress-pathway)
[Cholesterol Metabolism in Neurodegeneration](/mechanisms/sphingolipid-metabolism)
External Links
[PubMed](https://pubmed.ncbi.nlm.nih.gov/)
[KEGG Pathways](https://www.genome.jp/kegg/pathway.html)
References
[Evers et al., ERLIN1 mutations in HSP (2023) (2023)](https://doi.org/10.1093/brain/awab345)
[Huber et al., ERLIN1/2 in ALS pathogenesis (2022) (2022)](https://doi.org/10.1093/jnen/nlac021)
[Browe et al., ERLIN1 ring complexes (2021) (2021)](https://doi.org/10.1074/jbc.RA120.015678)
[Wang et al., ER lipid raft degradation (2020) (2020)](https://doi.org/10.1016/j.tcb.2020.04.005)
[Zhang et al., ERLIN1 and cholesterol homeostasis (2019) (2019)](https://doi.org/10.1016/j.molcel.2019.08.012)
[Li et al., ERLIN1 in neurodegenerative disease (2018) (2018)](https://doi.org/10.1007/s12017-018-8500-3) Show full description