Affinage

VPS54

Vacuolar protein sorting-associated protein 54 · UniProt Q9P1Q0

Length
977 aa
Mass
110.6 kDa
Annotated
2026-04-28
16 papers in source corpus 11 papers cited in narrative 11 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

VPS54 is a subunit of the GARP (Golgi-associated retrograde protein) tethering complex that mediates retrograde transport of endosome-derived vesicles to the trans-Golgi network, thereby maintaining TGN-resident protein homeostasis, glycosylation fidelity, and sorting receptor recycling. Its N-terminal region supports GARP complex assembly and stability, while its C-terminal α-helical bundle domain directs recognition of early endosomal compartments for cargo retrieval (PMID:16452629, PMID:20615984). Acute depletion of VPS54 causes accumulation of unresolved GARP-dependent vesicles, displacement of COPI/AP1/GGA coats, mislocalization of TGN-resident glycosyltransferases with consequent O-glycosylation defects, and mis-sorting of mannose-6-phosphate receptors [PMID:23708095, PMID:bio_10.1101_2024.10.07.617053]. The Vps54 L967Q missense mutation destabilizes the protein and depletes the entire GARP complex, causing motor neuron degeneration and defective acrosome biogenesis in the wobbler mouse (PMID:16244655, PMID:20615984, PMID:21866276).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2005 High

    Positional cloning of the wobbler mutation established VPS54 as a GARP complex subunit essential for motor neuron survival and spermiogenesis, answering whether this vesicle-tethering gene had organismal significance beyond yeast trafficking.

    Evidence Positional cloning and characterization of L967Q missense and Vps54-beta-geo null alleles in mouse

    PMID:16244655

    Open questions at the time
    • Mechanism by which GARP loss selectively kills motor neurons was not addressed
    • Whether the L967Q mutation disrupts GARP assembly or VPS54 stability was unresolved
  2. 2006 High

    Domain dissection revealed that VPS54 uses separate regions for two distinct functions—N-terminal complex assembly and C-terminal early-endosome recognition—resolving how a single subunit coordinates GARP integrity with cargo compartment specificity.

    Evidence Domain deletion/mutation analysis with retrograde transport assays (Snc1 retrieval) in yeast

    PMID:16452629

    Open questions at the time
    • Structural basis for C-terminal early endosome recognition was unknown
    • Whether domain functions are conserved in mammalian VPS54 was not tested
  3. 2010 High

    The crystal structure of the VPS54 C-terminal domain revealed a continuous α-helical bundle and showed that L967Q destabilizes the protein rather than disrupting GARP assembly per se, explaining why wobbler mice lose the entire GARP complex through reduced VPS54 half-life.

    Evidence X-ray crystallography at 1.7 Å resolution, in vitro folding/stability assays, and in vivo protein level measurements in mouse

    PMID:20615984

    Open questions at the time
    • Full-length VPS54 structure was not determined
    • How reduced VPS54 levels lead to selective motor neuron vulnerability remained unclear
  4. 2011 Medium

    Imaging of wobbler spermatids demonstrated that VPS54-dependent retrograde trafficking is required for proacrosomal vesicle coalescence, establishing the cellular mechanism linking GARP dysfunction to male infertility.

    Evidence Immunofluorescence and vesicle tracking in wobbler vs. wild-type spermatids

    PMID:21866276

    Open questions at the time
    • Molecular cargo of VPS54-dependent proacrosomal vesicles was not identified
    • Whether the acrosome defect is cell-autonomous was not fully resolved
  5. 2013 High

    Functional trafficking assays in VPS54-deficient cells demonstrated that GARP loss specifically impairs retrograde transport (cholera toxin B, mannose-6-phosphate receptors) without affecting endocytosis, and that complete VPS54 null causes embryonic lethality with neural tube defects.

    Evidence Retrograde transport assays, immunofluorescence for M6P receptors, and null mutant embryo analysis in mouse

    PMID:23708095

    Open questions at the time
    • Whether M6P receptor mis-sorting contributes to motor neuron degeneration was not tested
    • Mechanism of neural tube blebbing was not characterized
  6. 2020 Medium

    Drosophila studies placed VPS54 in a Rab7-dependent endosomal pathway at motor neuron synapses, showing conserved roles in controlling axon development and postsynaptic receptor composition via Syntaxin-16 localization.

    Evidence Drosophila scat null mutants and MN-specific RNAi with Rab5/Rab7/Rab11 genetic epistasis, NMJ morphology and Stx16 immunofluorescence

    PMID:32747448

    Open questions at the time
    • Whether Rab7 dependence operates identically in mammalian motor neurons is untested
    • Direct physical interaction between VPS54 and Rab7 was not shown
  7. 2021 Medium

    Characterization of adult Drosophila scat mutants revealed age-progressive locomotor defects and muscle atrophy dependent on Rab11, demonstrating that VPS54/GARP-mediated trafficking is required for long-term muscle and motor neuron maintenance across species.

    Evidence Lifespan, locomotor, and muscle morphometry assays with rab11 genetic epistasis in Drosophila

    PMID:34712272

    Open questions at the time
    • Whether muscle phenotype is cell-autonomous or secondary to motor neuron degeneration was not resolved
    • Rab11-dependent cargo in this context is unidentified
  8. 2024 High

    Acute VPS54 depletion in human cells directly identified GARP-dependent vesicles by EM, demonstrated early-onset O-glycosylation defects from glycosyltransferase recycling failure, and revealed broad displacement of Golgi coat proteins, providing the most comprehensive picture of GARP-dependent cellular functions.

    Evidence mAID degron rapid depletion in human cells with EM, immunofluorescence, glycosylation assays, and secretion assays (preprint)

    PMID:bio_10.1101_2024.10.07.617053

    Open questions at the time
    • Preprint; not yet peer-reviewed
    • Whether all displaced coat proteins reflect direct GARP tethering failure or secondary effects is unclear
    • Kinetic order of glycosylation vs. sorting defects not fully resolved
  9. 2026 Medium

    Identification of ELAPOR1 as a direct VPS54-binding partner that regulates GARP assembly in the testis provided the first tissue-specific modulator of VPS54 function, explaining how proacrosomal vesicle fusion is coordinated.

    Evidence Reciprocal co-immunoprecipitation, proximity labeling, mass spectrometry, and germ cell-specific ELAPOR1 knockout in mouse

    PMID:41993632

    Open questions at the time
    • Whether ELAPOR1 modulates VPS54/GARP function outside the testis is unknown
    • Structural basis of ELAPOR1–VPS54 interaction is not determined

Open questions

Synthesis pass · forward-looking unresolved questions
  • The mechanism by which GARP/VPS54 dysfunction selectively kills motor neurons while sparing most other cell types remains unresolved, as does the full-length structure of VPS54 and the identity of neuron-specific GARP cargo.
  • No neuron-specific GARP cargo has been identified
  • Full-length VPS54 structure unavailable
  • Whether VPS54 has GARP-independent functions is untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 3
Localization
GO:0005794 Golgi apparatus 3 GO:0005768 endosome 2 GO:0031410 cytoplasmic vesicle 2
Pathway
R-HSA-5653656 Vesicle-mediated transport 4 R-HSA-392499 Metabolism of proteins 2 R-HSA-1430728 Metabolism 1
Partners
ELAPOR1VPS51VPS52VPS53
Complex memberships
GARP complex

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2005 VPS54 is a subunit of the GARP complex essential for retrograde vesicle trafficking; the missense mutation L967Q in Vps54 causes motor neuron disease and defective spermiogenesis in the wobbler mouse, establishing VPS54 as required for motoneuron survival and spermiogenesis. Positional cloning, identification of missense mutation, characterization of lethal null allele (Vps54 beta-geo) in mouse Nature genetics High 16244655
2010 Crystal structure of the mouse Vps54 C-terminal fragment at 1.7 Å resolution reveals a continuous alpha-helical bundle architecture similar to other multisubunit tethering complexes; leucine-967 is buried in hydrophobic interactions critical for domain stability. The L967Q mutation does not prevent GARP complex assembly but greatly reduces Vps54 half-life and protein levels in vivo, causing loss of the entire GARP complex. X-ray crystallography (1.7 Å), in vitro folding/stability assay, in vivo protein level measurements, comparative sequence analysis Proceedings of the National Academy of Sciences of the United States of America High 20615984
2006 The N-terminal region of Vps54 is required for GARP complex assembly and stability, while the conserved C-terminal domain mediates localization to an early endocytic compartment. Mutation of the C-terminal domain causes a specific defect in retrieval of Snc1 from early endosomes but does not affect retrograde transport from late endosomes, demonstrating that separate domains recruit GARP to different upstream compartments. Domain deletion/mutation analysis in yeast, immunofluorescence localization, retrograde transport assays (Snc1 retrieval) Molecular biology of the cell High 16452629
2013 Loss of Vps54 function impairs retrograde transport of Cholera-toxin B subunit to the trans-Golgi network and causes mis-sorting of mannose-6-phosphate receptors and dependent cargo proteins, without affecting endocytosis per se; complete Vps54 null mutation causes embryonic lethality associated with membrane blebbing in the neural tube. Endocytosis assay, retrograde transport assay (cholera toxin B), immunofluorescence for mannose-6-phosphate receptors, analysis of null mutant embryos International journal of molecular sciences High 23708095
2011 Vps54(L967Q)-labeled vesicles fail to coalesce into the larger vesicle required for acrosome formation during spermiogenesis; the mutation impairs retrograde endocytic traffic necessary for acrosome biogenesis, with secondary defects in mitochondrial sorting and Sertoli-germ cell adhesion. Immunofluorescence, vesicle tracking in wobbler spermatids, UBPy endosome marker analysis Spermatogenesis Medium 21866276
2020 In Drosophila, Vps54 (scattered/scat) controls larval motor neuron axon development and postsynaptic density composition at the NMJ; MN-specific knockdown of Vps54 partially disrupts localization of the t-SNARE Syntaxin-16 to the TGN. Genetic interaction with dominant-negative Rab7 causes decreased postsynaptic Dlg and GluRIIB without affecting GluRIIA, placing Vps54 in a Rab7-dependent endosomal trafficking pathway at the synapse. Drosophila null mutants and MN-specific RNAi, NMJ morphology analysis, epistasis with Rab5/Rab7/Rab11 GTPases, immunofluorescence for Syntaxin-16 and postsynaptic markers Biology open Medium 32747448
2021 In Drosophila, null scat (Vps54 ortholog) mutant adults show shortened lifespan, male sterility, reduced muscle area, and age-progressive locomotor defects; genetic interaction between scat and rab11 in motor neurons controls age-progressive muscle atrophy. Loss-of-function allele generation, lifespan assay, locomotor behavior assay, muscle morphometry, genetic epistasis with rab11 Frontiers in genetics Medium 34712272
2013 In wobbler mouse testis lacking functional VPS54, proteome-wide changes include dramatic reduction of FABP3 and alterations in proteins involved in microtubule assembly and stress response (Hsp70-2, Hsp90α), indicating that VPS54/GARP complex dysfunction initiates a cascade of metabolic and stress abnormalities beyond acrosome defects. 2D-DIGE, mass spectrometry, immunoblot validation on wobbler testis tissue Proteomics Medium 24115398
2024 Acute depletion of VPS54 (via mAID degron) in human cells disrupts GARP function, causing: partial mislocalization/degradation of TGN-resident proteins (TGN46, ATP7A, TMEM87A, CPD, C1GALT1, GS15), early-onset O-glycosylation defects due to enzyme recycling failure, altered secretion of fibronectin and cathepsin D, accumulation of GARP-dependent vesicles and large vacuoles, and displacement of COPI, AP1, and GGA coats. Electron microscopy directly identified GARP-dependent vesicles and their cargo. mAID degron rapid protein depletion, immunofluorescence, electron microscopy, glycosylation assays, secretion assays, coat protein localization bioRxivpreprint High bio_10.1101_2024.10.07.617053
2026 ELAPOR1 interacts directly with VPS54 and affects VPS54-associated assembly of the GARP complex in the testis; loss of ELAPOR1 impairs fusion of proacrosomal vesicles and disrupts transport of Golgi and early endosome-related vesicles, identifying ELAPOR1 as a regulator of VPS54-mediated GARP complex formation. Co-immunoprecipitation, proximity labeling, mass spectrometry, immunofluorescence, germ cell-specific knockout mouse Theranostics Medium 41993632
2013 USP8 (deubiquitinating enzyme) partially colocalizes with VPS54 in motor neurons of the spinal cord, suggesting involvement in the same retrograde trafficking pathway; in wobbler spinal cord, both USP8 and Vps54(L967Q) lose their typical spot-like distribution and accumulate in proteinaceous aggregates. Immunofluorescence colocalization, histochemistry in wild-type and wobbler spinal cord Histochemistry and cell biology Low 23615794

Source papers

Stage 0 corpus · 16 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2005 Mutation of Vps54 causes motor neuron disease and defective spermiogenesis in the wobbler mouse. Nature genetics 189 16244655
2011 Failure of acrosome formation and globozoospermia in the wobbler mouse, a Vps54 spontaneous recessive mutant. Spermatogenesis 67 21866276
2010 Structural basis for the wobbler mouse neurodegenerative disorder caused by mutation in the Vps54 subunit of the GARP complex. Proceedings of the National Academy of Sciences of the United States of America 64 20615984
2006 Domains within the GARP subunit Vps54 confer separate functions in complex assembly and early endosome recognition. Molecular biology of the cell 41 16452629
2015 VPS54 and the wobbler mouse. Frontiers in neuroscience 38 26539077
2008 Evaluation of the Golgi trafficking protein VPS54 (wobbler) as a candidate for ALS. Amyotrophic lateral sclerosis : official publication of the World Federation of Neurology Research Group on Motor Neuron Diseases 29 18574757
2013 Loss of vps54 function leads to vesicle traffic impairment, protein mis-sorting and embryonic lethality. International journal of molecular sciences 27 23708095
2013 Pathoproteomics of testicular tissue deficient in the GARP component VPS54: the wobbler mouse model of globozoospermia. Proteomics 17 24115398
2017 Dynamic of contribution of UBPy-sorted cargo to acrosome biogenesis: effects of its derailment in a mouse model of globozoospermia, the infertile Vps54 (L967Q) mutant. Cell and tissue research 11 28299521
2013 The ESCRT-deubiquitinating enzyme USP8 in the cervical spinal cord of wild-type and Vps54-recessive (wobbler) mutant mice. Histochemistry and cell biology 9 23615794
2002 Identification, characterization and cytogenetic mapping of a yeast Vps54 homolog in rat and mouse. Gene 9 12039048
2021 Vps54 Regulates Lifespan and Locomotor Behavior in Adult Drosophila melanogaster. Frontiers in genetics 5 34712272
2020 Vps54 regulates Drosophila neuromuscular junction development and interacts genetically with Rab7 to control composition of the postsynaptic density. Biology open 5 32747448
2023 Generation and Analysis of hTERT-RPE1 VPS54 Knock-Out and Rescued Cell Lines. Methods in molecular biology (Clifton, N.J.) 4 36512226
2026 ELAPOR1 regulates VPS54-mediated GARP complex formation and proacrosomal vesicle fusion during spermatogenesis. Theranostics 0 41993632
2021 Knockdown of vps54 aggravates tamoxifen-induced cytotoxicity in fission yeast. Genomics & informatics 0 35172472