Affinage

VPS26B

Vacuolar protein sorting-associated protein 26B · UniProt Q4G0F5

Length
336 aa
Mass
39.2 kDa
Annotated
2026-04-28
21 papers in source corpus 12 papers cited in narrative 12 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

VPS26B is a component of a distinct mammalian retromer complex (VPS26B–VPS29–VPS35) that mediates endosomal cargo sorting and recycling. Its arrestin-like fold binds VPS35 through a conserved C-terminal surface patch with nanomolar affinity, competing with VPS26A for a single binding site to define two mutually exclusive retromer populations (PMID:18088321). VPS26B-retromer preferentially supports recycling of cargoes including GLUT1, glutamate receptors, and SORL1 rather than CI-M6PR retrieval, with VPS26B depletion in neurons selectively impairing synaptic recycling in Alzheimer-vulnerable brain regions (PMID:21920005, PMID:34965419). Independent of the canonical retromer, VPS26B acts as a Rab14 effector within a RhoBTB3–SHIP164–VPS26B complex at Golgi–endosome contacts to drive early endosome bud formation, and its trafficking function is regulated by NEK1-mediated phosphorylation (PMID:38565878, PMID:34376696).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2005 High

    Establishing VPS26B as a bona fide retromer subunit resolved whether VPS26 existed as a single gene or a family with distinct complex-forming capacity.

    Evidence Co-immunoprecipitation, yeast two-hybrid, subcellular fractionation, and TIRF microscopy in HeLa and A549 cells

    PMID:16190980

    Open questions at the time
    • No functional cargo sorting readout was performed
    • Distinction from VPS26A in vivo was not addressed
  2. 2007 High

    Structural determination of VPS26B revealed an arrestin-like fold and identified the C-terminal surface patch mediating VPS35 binding, showing that VPS26A and VPS26B compete for a single retromer binding site with nanomolar affinity.

    Evidence X-ray crystallography, ITC, structure-based mutagenesis, co-immunoprecipitation

    PMID:18088321

    Open questions at the time
    • Structural basis for cargo selectivity differences between VPS26A and VPS26B was not resolved
    • No in vivo confirmation of competitive binding
  3. 2010 High

    Knockout mice demonstrated that VPS26B-retromer is non-redundant with VPS26A-retromer in vivo, with loss of VPS26B leading to elevated sortilin levels and reduced VPS35 stability.

    Evidence Vps26b knockout mouse, co-immunoprecipitation, Western blot

    PMID:21040701

    Open questions at the time
    • Mechanism by which VPS26B loss destabilizes VPS35 was not determined
    • Sortilin trafficking was inferred from steady-state levels, not directly measured
  4. 2011 High

    Mapping differential cargo selectivity showed that VPS26B-retromer fails to interact with CI-M6PR—an effect dependent on the VPS26B C-terminal region—explaining why VPS26B expression promotes CI-M6PR degradation and cathepsin D secretion.

    Evidence Stable HEK293 cell lines, co-immunoprecipitation, deletion mutagenesis, cathepsin D secretion assay

    PMID:21920005

    Open questions at the time
    • Direct structural basis for C-terminal domain–mediated cargo exclusion was not resolved
    • Whether VPS26B-retromer has unique positive cargoes beyond CI-M6PR exclusion was unclear
  5. 2019 Medium

    Discovery that the viral protein M45 recruits VPS26B and TBC1D5 to target NEMO and RIPK1 aggregates for aggrephagy revealed an unexpected link between retromer and selective autophagy during immune evasion.

    Evidence Co-immunoprecipitation, proximity ligation assay, autophagy flux assays, siRNA knockdown in MCMV-infected cells

    PMID:31844296

    Open questions at the time
    • Whether VPS26B participates in aggrephagy in non-viral contexts is unknown
    • Mechanism of VPS26B recruitment by M45 was not structurally defined
  6. 2020 Medium

    Acute retromer inactivation using knocksideways technology confirmed that retromer (requiring VPS26A or VPS26B) is essential for GLUT1 cell-surface recycling but dispensable for CI-M6PR retrograde sorting, reframing the core cargo repertoire of mammalian retromer.

    Evidence Knocksideways acute inactivation, flow cytometry, quantitative microscopy in HeLa and H4 cells

    PMID:32747499

    Open questions at the time
    • VPS26B was not individually distinguished from VPS26A in this system
    • Mechanism of GLUT1 recognition by retromer was not identified
  7. 2021 High

    Two studies established that VPS26B-retromer is neuronally enriched and regulated by NEK1 phosphorylation: NEK1 directly phosphorylates VPS26B to maintain endosomal trafficking, while VPS26B depletion in neurons selectively impairs glutamate receptor and SORL1 recycling, causing synaptic dysfunction in the trans-entorhinal cortex.

    Evidence In vitro kinase assay, NEK1 knockout mice with RIPK1 genetic rescue; VPS26B depletion with electrophysiology, immunocytochemistry, and human brain tissue analysis

    PMID:34376696 PMID:34965419

    Open questions at the time
    • Specific phosphorylation site(s) on VPS26B and their structural consequences are not fully defined
    • Whether NEK1 regulation is neuron-specific or general is unknown
    • Causal link between VPS26B-retromer dysfunction and Alzheimer's disease pathogenesis remains correlative
  8. 2024 High

    Identification of VPS26B as a Rab14 effector within a RhoBTB3–SHIP164–VPS26B complex at Golgi–endosome contacts revealed a retromer-independent function in driving early endosome bud formation.

    Evidence Co-immunoprecipitation, siRNA knockdown, live-cell imaging, proximity ligation assay, domain mutagenesis

    PMID:38565878

    Open questions at the time
    • How VPS26B coordinates its retromer-dependent and Rab14-dependent functions is unknown
    • Whether VPS26B binds SHIP164 and VPS35 simultaneously or in mutually exclusive pools is unresolved
    • Lipid transfer activity of SHIP164 in this complex has not been functionally dissected

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include how VPS26B partitions between retromer-dependent and Rab14/SHIP164-dependent complexes, the structural basis for its distinct cargo selectivity versus VPS26A, and whether VPS26B dysfunction is causally linked to neurodegeneration.
  • No cryo-EM or crystal structure of a full VPS26B-retromer with cargo
  • No disease-causing mutations in VPS26B have been reported in human genetic studies
  • Dual complex membership (retromer vs. RhoBTB3–SHIP164) has not been quantified in physiological conditions

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 4
Localization
GO:0005768 endosome 3 GO:0005794 Golgi apparatus 1 GO:0005829 cytosol 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-5653656 Vesicle-mediated transport 5 R-HSA-9609507 Protein localization 3 R-HSA-9612973 Autophagy 1
Partners
GOLPH3NEK1RAB14RHOBTB3SHIP164TBC1D5VPS29VPS35
Complex memberships
RhoBTB3-SHIP164-VPS26Bretromer (VPS26B-VPS29-VPS35)

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 Crystal structure of mouse VPS26B was determined, revealing an arrestin-like fold. Structure-based mutagenesis showed that both VPS26A and VPS26B bind VPS35 through a highly conserved surface patch in the C-terminal subdomain, and this interaction is required for endosomal recruitment. VPS26A and VPS26B compete for a single VPS35/VPS29 binding site with nanomolar affinity, defining distinct retromer complexes in vitro and in vivo. X-ray crystallography, isothermal titration calorimetry, structure-based mutagenesis, co-immunoprecipitation Traffic High 18088321
2005 VPS26B is a peripheral membrane protein that co-precipitates with VPS35 and interacts directly with VPS35 by yeast two-hybrid analysis, establishing it as a subunit of the retromer complex. In HeLa cells, VPS26B localizes to the cytoplasm with low levels at the plasma membrane, while in A549 cells it co-localizes with actin-rich lamellipodia at the cell surface along with VPS35. TIRF microscopy confirmed VPS26B association with the plasma membrane. Co-immunoprecipitation, yeast two-hybrid, subcellular fractionation, immunofluorescence, TIRF microscopy Traffic High 16190980
2011 VPS26B-retromer associates with TBC1D5 and GOLPH3 but, unlike VPS26A-retromer, does not interact with the cation-independent mannose 6-phosphate receptor (CI-M6PR), leading to CI-M6PR degradation and increased cathepsin D secretion. The VPS26B C-terminal region is directly responsible for this differential cargo selectivity, as its deletion restores CI-M6PR cycling. VPS26B-retromer shows prolonged association with maturing endosomes relative to VPS26A-retromer. Stable cell lines (HEK293), co-immunoprecipitation, Western blot, immunofluorescence/colocalization with Rab proteins, deletion mutagenesis, cathepsin D secretion assay Traffic High 21920005
2010 Vps26b knockout mice lack the Vps26b-Vps29-Vps35 retromer complex despite normal Vps26a-retromer, and show a ~20% increase in sortilin protein levels, implicating Vps26b-retromer in retrograde transport of sortilin from endosomes to the TGN. Loss of Vps26b also results in a severe reduction of Vps35 protein at the cellular level. Vps26b knockout mouse generation, co-immunoprecipitation, Western blot, behavioral/histological analysis Biochemical and biophysical research communications High 21040701
2015 VPS26B-retromer negatively regulates plasma membrane repopulation of the protease-activated GPCR PAR-2 following stimulation. Overexpression of VPS26B causes a significant delay in PAR-2 plasma membrane resensitization without affecting initial receptor activation, endocytosis, ERK1/2 signaling, or calcium release. Stable HEK293 cell overexpression model, calcium flux assay, ERK1/2 signaling assay, flow cytometry/receptor internalization assay Cell biology international Medium 26113136
2019 The murine cytomegalovirus M45 protein recruits VPS26B (retromer component) and the LC3-interacting adaptor TBC1D5 to facilitate selective autophagy (aggrephagy) of NEMO and RIPK1 protein aggregates as a viral immune-evasion mechanism. Co-immunoprecipitation, proximity ligation assay, autophagy flux assays, siRNA knockdown Nature microbiology Medium 31844296
2021 NEK1 kinase phosphorylates VPS26B to regulate retromer-mediated endosomal trafficking. NEK1 deficiency disrupts endosomal trafficking of plasma membrane proteins and leads to lysosomal degradation of A20, promoting RIPK1-dependent cell death in cerebrovascular endothelial cells. In vitro phosphorylation assay, NEK1 knockout mice, genetic epistasis (RIPK1 inactivation rescue), proteomics, Western blot Nature communications High 34376696
2021 Neurons are enriched with a VPS26B-organized retromer core that is differentially dedicated to endosomal recycling. VPS26B depletion impairs glutamate receptor and SORL1 recycling, selectively causing synaptic dysfunction in the trans-entorhinal cortex, a region most vulnerable in Alzheimer's disease. Mouse model imaging, VPS26B depletion (siRNA/shRNA), electrophysiology, immunocytochemistry, behavioral assays, human brain tissue analysis Cell reports High 34965419
2024 VPS26B acts as a novel Rab14 effector and forms a complex with SHIP164 and the ATPase RhoBTB3 at Golgi-early endosome contacts to promote early endosome bud formation. Rab14 activity regulates SHIP164 association with early endosomes. Depletion of VPS26B leads to enlarged Rab14+ early endosomes without buds, phenocopying loss of SHIP164 or RhoBTB3. Co-immunoprecipitation, siRNA knockdown, live-cell imaging, confocal microscopy, proximity ligation assay, domain mutagenesis Cell discovery High 38565878
2008 Vps26b forms a distinct Vps26b-Vps29-Vps35 retromer complex in mouse testis, with the Vps26b-Vps35 interaction confirmed by immunoprecipitation and pull-down assay. Co-immunoprecipitation, pull-down assay, Western blot, RT-PCR Biochemical and biophysical research communications Medium 18656452
2020 Acute retromer inactivation by knocksideways technology (which requires VPS26A or VPS26B for retromer function) reveals that retromer is required for cell-surface recycling of GLUT1 but not for CI-MPR retrograde sorting in HeLa and H4 cells. Knocksideways (acute inactivation), flow cytometry, immunofluorescence, quantitative microscopy Journal of cell science Medium 32747499
2022 Retromer (containing VPS26A or VPS26B) co-immunoprecipitates with the centriolar protein CP110 and is required for CP110 removal from the mother centriole, establishing a role for retromer in primary ciliogenesis in mammalian cells. VPS35 localizes to the primary cilium. Co-immunoprecipitation, siRNA knockdown, immunofluorescence, ciliogenesis assay, CRISPR knockout in C. elegans Journal of cell science Medium 35510502

Source papers

Stage 0 corpus · 21 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2007 Structure of Vps26B and mapping of its interaction with the retromer protein complex. Traffic (Copenhagen, Denmark) 98 18088321
2011 Vps26A and Vps26B subunits define distinct retromer complexes. Traffic (Copenhagen, Denmark) 84 21920005
2005 A novel mammalian retromer component, Vps26B. Traffic (Copenhagen, Denmark) 76 16190980
2019 Herpesviruses induce aggregation and selective autophagy of host signalling proteins NEMO and RIPK1 as an immune-evasion mechanism. Nature microbiology 54 31844296
2021 Alzheimer's vulnerable brain region relies on a distinct retromer core dedicated to endosomal recycling. Cell reports 51 34965419
2010 Implication of mouse Vps26b-Vps29-Vps35 retromer complex in sortilin trafficking. Biochemical and biophysical research communications 50 21040701
2021 NEK1-mediated retromer trafficking promotes blood-brain barrier integrity by regulating glucose metabolism and RIPK1 activation. Nature communications 38 34376696
2016 Atypical parkinsonism-associated retromer mutant alters endosomal sorting of specific cargo proteins. The Journal of cell biology 38 27528657
2014 Genetic variability of the retromer cargo recognition complex in parkinsonism. Movement disorders : official journal of the Movement Disorder Society 23 25475142
2020 Dysregulation of the Retromer Complex System in Down Syndrome. Annals of neurology 21 32320094
2021 Viral Induced Protein Aggregation: A Mechanism of Immune Evasion. International journal of molecular sciences 19 34502533
2020 Acute inactivation of retromer and ESCPE-1 leads to time-resolved defects in endosomal cargo sorting. Journal of cell science 19 32747499
2023 Pharmacologic enhancement of retromer rescues endosomal pathology induced by defects in the Alzheimer's gene SORL1. Stem cell reports 17 37949073
2008 Identification of novel retromer complexes in the mouse testis. Biochemical and biophysical research communications 15 18656452
2023 Retromer Proteins Reduced in Down Syndrome and the Dp16 Model: Impact of APP Dose and Preclinical Studies of a γ-Secretase Modulator. Annals of neurology 9 37042072
2022 The retromer complex regulates C. elegans development and mammalian ciliogenesis. Journal of cell science 8 35510502
2022 Identification of novel rare copy number variants associated with sporadic tetralogy of Fallot and clinical implications. Clinical genetics 7 35882632
2015 Vps26B-retromer negatively regulates plasma membrane resensitization of PAR-2. Cell biology international 7 26113136
2025 Variations in rumen microbiota and host genome impacted feed efficiency in goat breeds. Frontiers in microbiology 4 39944650
2024 Biogenesis of Rab14-positive endosome buds at Golgi-endosome contacts by the RhoBTB3-SHIP164-Vps26B complex. Cell discovery 4 38565878
2011 Quantitative analysis of retromer complex-related genes during embryo development in the mouse. Molecules and cells 0 21359680