Affinage

ZFYVE27

Protrudin · UniProt Q5T4F4

Length
411 aa
Mass
45.8 kDa
Annotated
2026-04-28
19 papers in source corpus 9 papers cited in narrative 9 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

ZFYVE27 (Protrudin) is an ER-resident membrane protein that functions as a tethering factor at ER–organelle membrane contact sites, regulating ER tubular network morphology, endosomal positioning, lipid transfer, and neurite outgrowth. It contains hydrophobic hairpin domains that anchor it in the tubular ER, a noncanonical FYVE domain that binds PI3P, an FFAT domain for VAP interaction, and a Rab-binding domain; it oligomerizes via its HR3 domain, which is required for protrusion formation, and interacts with ER-shaping proteins (atlastins, REEPs, reticulons), KIF5, spastin, and the lipid transfer protein PDZD8 (PMID:22216323, PMID:23969831, PMID:24668814, PMID:33912962). A neuron-specific long isoform generated by SRRM4-dependent inclusion of a microexon promotes neurite outgrowth more effectively than the shorter isoform, and Protrudin additionally regulates FAK activation and endothelial cell migration (PMID:28106138, PMID:35368213). A missense mutation (G191V) linked to hereditary spastic paraplegia SPG33 disrupts spastin binding and increases ER stress susceptibility, while Protrudin-knockout mice lack HSP phenotypes, indicating that disease-associated mutations act through gain-of-toxic-function (PMID:16826525, PMID:24668814, PMID:33172474).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2006 High

    Identification of ZFYVE27 as a spastin-binding partner and SPG33 disease gene established it as a player in HSP pathogenesis and linked it mechanistically to microtubule-severing via spastin.

    Evidence Yeast two-hybrid screen, reciprocal co-immunoprecipitation, co-localization, and functional analysis of the G191V mutation in mammalian cells

    PMID:16826525

    Open questions at the time
    • Mechanism by which disrupted spastin interaction leads to axonal degeneration unknown
    • Whether other SPG proteins interact with ZFYVE27 was unexplored
    • Subcellular compartment and membrane association not yet defined
  2. 2011 High

    Demonstrating that Protrudin is a peripheral membrane protein that binds PI3P and oligomerizes via HR3 revealed how it associates with membranes and showed oligomerization is functionally required for neurite extension.

    Evidence Sucrose gradient centrifugation, Triton X-114 phase separation, lipid-binding assays, and dominant-negative HR3 deletion in neurite outgrowth assays

    PMID:22216323

    Open questions at the time
    • Stoichiometry of oligomers in vivo not resolved
    • Which PI3P-containing compartments are relevant for function unclear
    • Structural basis of HR3-mediated self-association unknown
  3. 2013 High

    Defining Protrudin's multi-domain architecture (hydrophobic hairpins, FYVE, FFAT, Rab-binding domains) and its interactions with atlastins, reticulons, and KIF5 established it as an ER-shaping protein that regulates ER tubular morphology.

    Evidence Co-immunoprecipitation, domain mapping, and ER morphology assays in mammalian cells

    PMID:23969831

    Open questions at the time
    • Relative contribution of each domain to ER morphogenesis not dissected
    • Whether Protrudin directly bends membranes or acts via recruitment of other shapers unclear
  4. 2014 High

    Proteomic identification of Protrudin's interactome from mouse brain confirmed interactions with multiple HSP-related ER proteins in vivo and showed the G191V mutant gains stability and sensitizes cells to ER stress, supporting a gain-of-toxic-function disease model.

    Evidence Purification of Protrudin complexes from transgenic mouse brain, co-immunoprecipitation, membrane topology analysis, ER stress assays

    PMID:24668814

    Open questions at the time
    • Mechanism linking increased mutant stability to ER stress susceptibility unknown
    • Whether gain-of-function toxicity involves dominant-negative disruption of ER morphology or a neomorphic activity not distinguished
  5. 2017 High

    Discovery that SRRM4 drives inclusion of a neuron-specific microexon in ZFYVE27, producing a long isoform with enhanced neurite-outgrowth-promoting activity, explained tissue-specific functional regulation of Protrudin.

    Evidence RNA splicing assays, SRRM4 knockdown, exon deletion mutants, and neurite outgrowth assays in Neuro2A and ES cells

    PMID:28106138

    Open questions at the time
    • How the 7-amino-acid microexon insert alters protein interactions or conformation unknown
    • Relevance of the long isoform to HSP pathogenesis not tested
  6. 2020 Medium

    Protrudin-knockout mice exhibit behavioral abnormalities but not HSP, establishing that SPG33 mutations cause disease through gain-of-toxic-function rather than haploinsufficiency.

    Evidence Global knockout mouse with comprehensive behavioral battery testing

    PMID:33172474

    Open questions at the time
    • Molecular basis of behavioral abnormalities (hyperactivity, depression-like behavior) not characterized
    • Whether compensatory mechanisms mask loss-of-function HSP phenotypes in mice not excluded
    • Single lab study; independent replication pending
  7. 2021 High

    Identification of PDZD8 as a Protrudin-interacting lipid transfer protein at ER–late endosome/lysosome contact sites revealed a direct mechanism by which Protrudin supports inter-organelle lipid transport and endosome positioning required for neurite outgrowth.

    Evidence Co-immunoprecipitation, in vitro lipid transfer reconstitution, organelle positioning and neurite outgrowth assays

    PMID:33912962

    Open questions at the time
    • Which specific lipid species are most important for neurite outgrowth not determined
    • Whether Protrudin–PDZD8 contact sites are disrupted by HSP mutations not tested
  8. 2022 Medium

    Demonstrating that Protrudin regulates FAK activation, polarized phospho-FAK distribution, and mTOR/S6K signaling in endothelial cells expanded its functional repertoire beyond neurons to vascular biology.

    Evidence siRNA knockdown in HUVECs/HAECs, phospho-FAK immunofluorescence, tube formation assays, mTOR/S6K signaling assays, and retinal vascular analysis in knockout mice

    PMID:35368213

    Open questions at the time
    • Mechanism linking ER contact site function to FAK activation not defined
    • Whether endothelial phenotype involves PDZD8-dependent lipid transfer unknown
    • Single-lab finding; independent confirmation in additional vascular beds needed

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis of Protrudin oligomerization, the precise mechanism by which disease mutations confer gain-of-toxic-function, and how Protrudin coordinates lipid transfer with ER morphogenesis in axons remain unresolved.
  • No high-resolution structure of Protrudin or its complexes available
  • Gain-of-toxic-function mechanism (neomorphic vs. dominant-negative) not distinguished
  • Relative contributions of lipid transfer, ER shaping, and Rab11 inactivation to neurite outgrowth not dissected

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0005198 structural molecule activity 2 GO:0008289 lipid binding 2
Localization
GO:0005783 endoplasmic reticulum 3 GO:0005768 endosome 1
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-1643685 Disease 2 R-HSA-1852241 Organelle biogenesis and maintenance 2 R-HSA-9609507 Protein localization 2
Partners
ATL1KIF5APDZD8REEP1RTN4SPASTSRRM4VAPA

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2006 ZFYVE27 (Protrudin) was identified as a specific spastin-binding protein via yeast two-hybrid screen, validated by in vivo co-immunoprecipitation and co-localization in mammalian cells. A pathogenic missense mutation in ZFYVE27 (SPG33) severely disrupts its interaction with spastin and causes an aberrant intracellular tubular structure pattern. Yeast two-hybrid, co-immunoprecipitation, co-localization in mammalian cells, mutant functional analysis American journal of human genetics High 16826525
2011 ZFYVE27 (Protrudin) self-interacts and oligomerizes into dimer/tetramer forms; the core self-interaction region resides within the third hydrophobic region (HR3). ZFYVE27 is a peripheral membrane protein that binds phosphatidylinositol 3-phosphate. Oligomerization is necessary for neurite extension, as deletion of HR3 causes a dominant-negative effect abolishing protrusion formation. Yeast two-hybrid, co-immunoprecipitation, co-localization, sucrose gradient centrifugation, subcellular fractionation, Triton X-114 membrane phase separation, lipid-binding assay, dominant-negative expression PloS one High 22216323
2013 Protrudin (ZFYVE27/SPG33) contains hydrophobic intramembrane hairpin domains, interacts with tubular ER proteins (atlastins and ER-shaping proteins), and functions in ER morphogenesis by regulating the sheet-to-tubule balance. Protrudin also interacts with KIF5 and harbors a Rab-binding domain, a noncanonical FYVE domain, and an FFAT domain. Co-immunoprecipitation, domain analysis, ER morphology assays, interaction studies with ER-shaping proteins Proceedings of the National Academy of Sciences of the United States of America High 23969831
2014 Protrudin localizes predominantly to the tubular ER, promotes formation and stabilization of the tubular ER network when overexpressed, and interacts with other HSP-related proteins including myelin proteolipid protein 1 (SPG2), atlastin-1 (SPG3A), REEP1 (SPG31), REEP5, Kif5A/B/C, and reticulons 1, 3, and 4. The disease-associated mutant Protrudin(G191V) has increased intracellular stability and cells expressing it show increased susceptibility to ER stress. Membrane topology analysis revealed one of three hydrophobic segments forms a hydrophobic hairpin domain. Proteomics of purified protrudin complexes from transgenic mouse brain, co-immunoprecipitation, membrane topology analysis, ER morphology assay, ER stress assay The Journal of biological chemistry High 24668814
2017 SRRM4 regulates alternative splicing of ZFYVE27 (protrudin) pre-mRNA to include a neuron-specific microexon (exon L) encoding seven amino acids. The resulting long isoform (protrudin-L) promotes neurite outgrowth more effectively than the shorter isoform (protrudin-S). SRRM4 recognizes a UGC motif upstream of exon L for this splicing event. Deletion of exon L inhibits neurite outgrowth. RNA splicing assay, shRNA knockdown of SRRM4, exon deletion mutants, neurite outgrowth assay in Neuro2A and embryonic stem cells Scientific reports High 28106138
2019 Protrudin functions as a tethering factor at membrane contact sites (MCSs) between the ER and other organelles. Its pleiotropic molecular functions at MCSs include inactivation of small GTPase Rab11, bending of the ER membrane, and functional interactions with motor protein KIF5 and the ER protein VAP. Review of experimental findings (domain functional analysis, interaction studies) Proceedings of the Japan Academy. Series B, Physical and biological sciences Medium 31406056
2020 Protrudin-deficient mice display pleiotropic behavioral abnormalities (hyperactivity, depression-like behavior, attention deficits, impaired fear-conditioning memory) but no signs of HSP, suggesting that HSP-associated mutations act via gain-of-toxic-function rather than loss-of-function. Knockout mouse generation, comprehensive behavioral battery testing Molecular brain Medium 33172474
2021 Protrudin (ZFYVE27) interacts with PDZD8, an SMP domain-containing protein that acts as a tether at ER-late endosome/lysosome (LE/lys) membrane contact sites and transfers lipids (glycerophospholipids and ceramides) between membranes. This interaction is required for LE/lys positioning and neurite outgrowth. Co-immunoprecipitation, in vitro lipid transfer assay, lipid-binding assay, organelle positioning assay, neurite outgrowth assay Journal of cell science High 33912962
2022 Protrudin (ZFYVE27) regulates FAK activation, endothelial cell migration, and angiogenesis. Knockdown of Protrudin inhibits FAK activation and disrupts polarized phospho-FAK distribution in HUVECs and HAECs, and reduces VEGF-mediated S6K activation via perinuclear mTOR accumulation. Mice with global Protrudin deletion show reduced retinal vascular progression. siRNA knockdown, phospho-FAK immunofluorescence, tube formation assay, mTOR/S6K signaling assays, protrudin knockout mouse retinal vascular analysis Cellular and molecular life sciences : CMLS Medium 35368213

Source papers

Stage 0 corpus · 19 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 Hereditary spastic paraplegias with autosomal dominant, recessive, X-linked, or maternal trait of inheritance. Journal of the neurological sciences 228 22554690
2006 ZFYVE27 (SPG33), a novel spastin-binding protein, is mutated in hereditary spastic paraplegia. American journal of human genetics 113 16826525
2018 Clinical spectrum and genetic landscape for hereditary spastic paraplegias in China. Molecular neurodegeneration 70 29980238
2013 Protrudin binds atlastins and endoplasmic reticulum-shaping proteins and regulates network formation. Proceedings of the National Academy of Sciences of the United States of America 56 23969831
2014 Protrudin regulates endoplasmic reticulum morphology and function associated with the pathogenesis of hereditary spastic paraplegia. The Journal of biological chemistry 53 24668814
2021 PDZD8-mediated lipid transfer at contacts between the ER and late endosomes/lysosomes is required for neurite outgrowth. Journal of cell science 46 33912962
2017 SRRM4-dependent neuron-specific alternative splicing of protrudin transcripts regulates neurite outgrowth. Scientific reports 39 28106138
2008 Lack of spartin protein in Troyer syndrome: a loss-of-function disease mechanism? Archives of neurology 33 18413476
2018 Protein-protein interactions reveal key canonical pathways, upstream regulators, interactome domains, and novel targets in ALS. Scientific reports 30 30283000
2016 A Subpopulation of Label-Retaining Cells of the Kidney Papilla Regenerates Injured Kidney Medullary Tubules. Stem cell reports 19 27117784
2011 Oligomerization of ZFYVE27 (Protrudin) is necessary to promote neurite extension. PloS one 18 22216323
2022 Protrudin regulates FAK activation, endothelial cell migration and angiogenesis. Cellular and molecular life sciences : CMLS 17 35368213
2008 A novel candidate locus on chromosome 11p14.1-p11.2 for autosomal dominant hereditary spastic paraplegia. Chinese medical journal 13 18364116
2020 Protrudin-deficient mice manifest depression-like behavior with abnormalities in activity, attention, and cued fear-conditioning. Molecular brain 8 33172474
2019 Roles of protrudin at interorganelle membrane contact sites. Proceedings of the Japan Academy. Series B, Physical and biological sciences 6 31406056
2022 Demographic and Genome Wide Association Analyses According to Muscle Mass Using Data of the Korean Genome and Epidemiology Study. Journal of Korean medical science 4 36573383
2008 Refinement of the SPG9 locus on chromosome 10q23.3-24.2 and exclusion of candidate genes. European journal of neurology 4 18394049
2022 MYO1H is a novel candidate gene for autosomal dominant pure hereditary spastic paraplegia. Molecular genetics and genomics : MGG 2 35704118
2026 Causal Association Between Plasma Proteins and Pericarditis: A Mendelian Randomization Study With Therapeutic Target Identification. Mediators of inflammation 0 41674924