Affinage

GET1

Guided entry of tail-anchored proteins factor 1 · UniProt O00258

Length
174 aa
Mass
19.8 kDa
Annotated
2026-06-10
31 papers in source corpus 18 papers cited in narrative 18 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/7 claims corpus-supported (86%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

The GET1 symbol in this corpus resolves to two distinct, internally coherent proteins: WRB, an ER-resident membrane insertase of the GET/TRC40 tail-anchored (TA) protein targeting pathway, and GRHL3/GET1, a nuclear Grainyhead-family transcription factor; both are well-evidenced and treated below. As WRB, the protein is an ER membrane receptor that, with its partner CAML/Get2, captures TRC40/Get3-delivered TA proteins and inserts them into the bilayer (PMID:21444755, PMID:24392163). The cytosolic coiled-coil domain of Get1/WRB binds the TRC40/Get3 ATPase and, together with two molecular recognition features in the Get2/CAML cytosolic domain, stabilizes the open Get3 dimer conformation that drives substrate release (PMID:22684149, PMID:34614151). Separately from this cytosolic recruitment function, the transmembrane segments of the Get1/2 (WRB/CAML) complex provide a bona fide insertase activity that captures the substrate TM domain and forms an aqueous channel which is gated by Get3 binding (PMID:25043001, PMID:36640319); a single Get1/2 heterodimer suffices for insertion, with Get1 and Get2 binding asymmetrically to opposing Get3 subunits (PMID:28877464). WRB further acts catalytically to enforce correct three-TM topogenesis of CAML, preventing accumulation of aberrant topoforms that are proteasomally degraded (PMID:31417168). In vivo, WRB is required for biogenesis of synaptic-vesicle and TA proteins such as otoferlin and syntaxin 5 in sensory hair cells and photoreceptors, where loss disrupts ribbon synapse vesicle replenishment, hearing, and vision (PMID:27458190, PMID:27273592, PMID:28000760), and the Get1/2 complex supports mitophagy in yeast independently of Get3 (PMID:29673596). As the transcription factor GRHL3/GET1, the protein localizes to the nucleus, binds Grainyhead DNA sites, dimerizes, and carries both activation and repression domains (PMID:12666198); it directly binds and regulates differentiation gene promoters, recruiting Trithorax complexes (PMID:19494835, PMID:22829784), represses the miR-21 promoter in epidermis (PMID:22614019), and acts upstream of TGFα in EGFR/ERK signaling during eyelid closure (PMID:18485343). An unrelated erythrocyte Wrb blood-group antigen arises from a glycophorin A–band 3 complex (PMID:2383660).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 1990 Medium

    Established the original molecular basis of the erythrocyte Wrb antigen, showing it depends on a glycophorin A–band 3 membrane complex rather than a single protein.

    Evidence Radioimmunoassay and co-immunoprecipitation of erythrocyte membrane proteins with monoclonal anti-Wrb antibodies

    PMID:2383660

    Open questions at the time
    • Distinct from the ER insertase WRB and the transcription factor GET1; relationship to those proteins not addressed
    • No structural detail of the GPA–band 3 interface
  2. 2003 Medium

    Defined GET1/GRHL3 as a nuclear Grainyhead-family transcription factor with DNA-binding, dimerization, and dual activator/repressor domains, framing its role in epithelial gene regulation.

    Evidence Yeast two-hybrid for LMO-4 partners, EMSA, transactivation reporter assays, dimerization and localization assays

    PMID:12666198

    Open questions at the time
    • Direct target genes not yet identified
    • No genome-wide binding map
    • Mechanism of repression-domain function unresolved
  3. 2008 Medium

    Placed Grhl3/Get1 upstream of EGFR/ERK signaling in morphogenesis by showing it controls TGFα expression required for leading-edge actin dynamics during eyelid closure.

    Evidence Get1 knockout mouse with phospho-EGFR/ERK and F-actin staining and TGFα organ-culture rescue

    PMID:18485343

    Open questions at the time
    • Whether Get1 binds the TGFα promoter directly not established
    • Single lab
  4. 2009 Medium

    Demonstrated direct promoter binding by Grhl3/Get1, linking it to terminal epithelial differentiation through activation of uroplakin II and apical membrane specialization.

    Evidence ChIP, genome-wide expression profiling, and barrier-defect phenotype in Get1 knockout bladder

    PMID:19494835

    Open questions at the time
    • Identity of cooperating chromatin factors not yet defined here
    • Histone-modification dependence described correlatively
  5. 2011 High

    Identified WRB as the ER membrane receptor for the TRC40/Asna1 TA-targeting ATPase, mapping the binding interface to its cytosolic coiled-coil domain.

    Evidence Co-immunoprecipitation, imaging, and dominant-negative soluble coiled-coil interference in cells

    PMID:21444755

    Open questions at the time
    • Did not resolve how WRB drives substrate release or insertion
    • Role of a partner subunit not yet established
  6. 2012 High

    Provided the structural mechanism by which Get1 opens Get3, showing the Get1 cytosolic domain binds two interfaces of the Get3 dimer to promote substrate release.

    Evidence X-ray crystallography of Get3–Get1CD complexes plus interface-mutant binding assays

    PMID:22684149

    Open questions at the time
    • Did not address insertase activity of the TM segments
    • Contribution of Get2 to opening not quantified here
  7. 2012 Medium

    Connected GRHL3/GET1 to chromatin machinery and miRNA control, showing it recruits Trithorax complexes to differentiation genes and represses miR-21 to restrain transformation.

    Evidence Genome-wide chromatin analysis, co-recruitment assays, ChIP, miRNA profiling, and tumor-formation assays in Grhl3 knockout skin

    PMID:22614019 PMID:22829784

    Open questions at the time
    • Direct biochemical contact between GRHL3 and Trithorax subunits not mapped
    • Mechanism of miR-21 promoter repression not detailed
  8. 2014 High

    Separated the insertase function of the Get1/2 transmembrane domains from cytosolic Get3 recruitment, and showed WRB+CAML are necessary and sufficient to constitute the receptor.

    Evidence Cell reporter assays and biochemical reconstitution with TM-domain mutants; yeast complementation by WRB/CAML with binding measurements

    PMID:24392163 PMID:25043001

    Open questions at the time
    • Physical nature of the insertion conduit not yet defined
    • Stoichiometry of the active complex unresolved
  9. 2016 High

    Established the physiological importance of WRB-dependent TA insertion in excitable sensory cells, with otoferlin and synaptic-vesicle proteins as key clients and the TRC40-binding interface as functionally essential.

    Evidence Hair-cell and photoreceptor Wrb knockout/mutant in zebrafish and mice with electrophysiology, EM, immunostaining, and R73A binding-defective rescue

    PMID:27273592 PMID:27458190

    Open questions at the time
    • Full client repertoire in these cells not enumerated
    • Whether vesicle defects are entirely TA-insertion-dependent not fully resolved
  10. 2016 Medium

    Showed that in vitro client status does not predict in vivo receptor dependence, identifying syntaxin 5 as exquisitely WRB-sensitive and an autophagy target upon pathway failure.

    Evidence Tissue-specific WRB knockout mice with western blotting, TA-fate assays, and a yeast-to-mammalian client screen

    PMID:28000760

    Open questions at the time
    • Determinants of differential substrate sensitivity unknown
    • Single lab
  11. 2018 Medium

    Revealed a Get3-independent role for the Get1/2 insertase in mitophagy, implicating a membrane-intrinsic function downstream of Atg32.

    Evidence Yeast get1/2 and get3 deletion mutants with mitophagy assays during respiratory growth

    PMID:29673596

    Open questions at the time
    • The relevant TA substrate(s) for mitophagy not identified
    • Whether the role is conserved in mammals untested here
  12. 2021 High

    Quantified how Get1/2 complex assembly cooperatively enhances Get3•TA binding, defining Get2 MoRFs and Get1 remodeling as jointly required for substrate release.

    Evidence Fluorescence binding assays, single-molecule FRET, and in vivo insertion assays with MoRF mutants

    PMID:34614151

    Open questions at the time
    • Precise ordering of conformational steps during release not fully resolved
    • Coupling to membrane insertion step not addressed
  13. 2022 Medium

    Demonstrated that Get1/2 forms a gated aqueous channel whose opening, sealed by Get3, is required for TA release and possibly translocation of C-terminal hydrophilic segments.

    Evidence Bulk fluorescence and microfluidics channel assays in reconstituted bilayers with channel-activity mutants

    PMID:36640319

    Open questions at the time
    • Channel model not yet independently replicated
    • Direct evidence for C-terminal translocation not provided
    • No high-resolution channel structure

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved how the cytosolic substrate-release machinery is physically coupled to the transmembrane insertase/channel within a single Get1/2(WRB/CAML)–Get3 reaction cycle, and what governs substrate-specific receptor dependence in vivo.
  • No integrated structure of the full membrane-embedded WRB/CAML–Get3–substrate intermediate
  • Rules predicting which TA proteins require WRB in vivo unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 4 GO:0005198 structural molecule activity 3 GO:0140096 catalytic activity, acting on a protein 3 GO:0003677 DNA binding 2 GO:0005215 transporter activity 1
Localization
GO:0005783 endoplasmic reticulum 4 GO:0005886 plasma membrane 3 GO:0005634 nucleus 2
Pathway
R-HSA-74160 Gene expression (Transcription) 4 R-HSA-392499 Metabolism of proteins 3 R-HSA-9609507 Protein localization 3 R-HSA-1266738 Developmental Biology 2 R-HSA-9612973 Autophagy 1
Partners
CAMLGET3GYPALMO4SLC4A1TRC40
Complex memberships
GET insertase complex (WRB/Get1–CAML/Get2)

Evidence

Reading pass · 18 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 WRB (GET1 mammalian homolog) is an ER-resident membrane protein that acts as the receptor for TRC40/Asna1 (yeast Get3). The coiled-coil domain of WRB was identified as the binding site for TRC40/Asna1, and a soluble form of this domain interferes with TRC40/Asna1-mediated TA protein membrane insertion. Biochemical co-immunoprecipitation, cell imaging, dominant-negative soluble coiled-coil domain interference assay Journal of cell science High 21444755
2014 The transmembrane domains of the Get1/2 (WRB/CAML) complex possess a bona fide insertase function distinct from their cytosolic domain functions: they capture the transmembrane domain of TA protein substrates and release them from Get3, defining a pre-integrated intermediate. Mutations in the Get1/2 transmembrane domains abolish TA protein insertion without disrupting Get3 binding by the cytosolic domains. Cell-based reporter assays and biochemical reconstitution with transmembrane domain mutants Nature High 25043001
2014 WRB and CAML together are necessary and sufficient to constitute a functional ER membrane receptor for TRC40-mediated TA protein targeting. WRB and CAML expressed in yeast lacking Get1/Get2 rescue GET receptor mutant growth phenotypes and restore TA protein targeting. The membrane-spanning segments of CAML are essential for creating a functional receptor with WRB. Yeast complementation of GET1/GET2 deletion, in vivo TA protein targeting assays, binding parameter measurements for TRC40/WRB-CAML interaction PloS one High 24392163
2012 The cytoplasmic domain of Get1 (Get1CD) stabilizes the open dimer conformation of Get3 ATPase by binding at two distinct interfaces simultaneously, promoting substrate release. Crystal structures of ADP-bound Get3 in complex with Get1CD were solved at 3.0 Å (open) and 4.5 Å (semi-open) resolution. X-ray crystallography of Get3–Get1CD complex; biochemical binding assays with interface mutants Journal of molecular biology High 22684149
2017 A single Get1/2 heterodimer is sufficient for TA protein insertion into the ER membrane. The conserved cytosolic regions of Get1 and Get2 bind asymmetrically to opposing subunits of the Get3 homodimer. Single-molecule and bulk fluorescence measurements in reconstituted lipid bilayers; quantitative in vitro insertion analysis Cell reports High 28877464
2019 WRB acts catalytically to assist the topogenesis of its partner CAML: in the presence of sufficient WRB, CAML is inserted into the ER membrane with three transmembrane segments in its C-terminal region. Without sufficient WRB, CAML fails to adopt the correct topology and instead generates aberrant topoforms that accumulate in ER-associated clusters and are degraded by the proteasome. Topology assays, proteasome inhibition, microscopy of ER-associated clusters in WRB-depleted cells Scientific reports Medium 31417168
2021 Complex assembly between the cytosolic domains (CDs) of Get1 and Get2 strongly enhances the affinity of individual subunits for the Get3•TA targeting complex. Two molecular recognition features (MoRFs) in Get2CD induce Get3 opening, while Get1CD remodels Get3 conformation; both subunits are required for optimal TA release from Get3. Mutation of the MoRFs attenuates TA insertion in vivo. Fluorescence binding assays measuring Get1CD and Get2CD affinity for Get3•TA, single-molecule FRET, in vivo TA insertion assays with MoRF mutants The Journal of cell biology High 34614151
2022 Get1/2 forms an aqueous channel (~2.5 nm diameter, corresponding to circumference of two Get1/2 complexes) in reconstituted bilayers. Get3 binding seals the Get1/2 channel, which dynamically opens and closes. Channel activity is required for releasing TA proteins from Get3 for membrane insertion; Get1/2 is proposed to also translocate C-terminal hydrophilic segments. Bulk fluorescence and microfluidics channel-forming assays in reconstituted bilayers; mutational analysis of channel activity correlated with TA protein insertion Cell reports Medium 36640319
2016 WRB mediates insertion of otoferlin (a TA protein essential for hair cell exocytosis) into the ER via the TRC40 pathway. Disruption of Wrb in zebrafish hair cells reduced otoferlin levels, impaired hearing, and caused defective synaptic vesicle replenishment. Transgenic Wrb rescue and otoferlin overexpression restored hearing in zebrafish. A WRB mutant (R73A) unable to bind Trc40 failed to rescue, establishing the TRC40-binding interface as functionally essential. Hair cell-specific Wrb knockout in zebrafish and mice; electrophysiology (patch-clamp), auditory recordings, immunohistochemistry, transgenic rescue including binding-defective mutant The EMBO journal High 27458190
2016 WRB (zebrafish wrb/pwi) is required for synaptic vesicle biogenesis at ribbon synapses in photoreceptors. Mutation of wrb reduced Rab3 and CSP/Dnajc5 in hair cells and photoreceptors, reduced ribbon number and vesicles surrounding ribbons, and abolished the optokinetic response. Morpholino knockdown of trc40 phenocopied wrb mutation, and overexpression of wrbR73A (cannot bind Trc40) failed to rescue, confirming that the Trc40-binding interface of WRB is required. ERG, optokinetic response, immunohistochemistry, electron microscopy in zebrafish wrb mutants; morpholino knockdown of trc40; rescue with wild-type vs. R73A mutant wrb Investigative ophthalmology & visual science High 27273592
2016 WRB knockout mice show that SNARE syntaxin 5 (Stx5) is extremely sensitive to TRC40 pathway disruption and is an autophagy target when the pathway is impaired. In contrast, other TA proteins showed differential sensitivity to WRB loss, demonstrating that in vitro TRC40-pathway client status does not predict in vivo dependence on the receptor. Tissue-specific WRB knockout mouse models; western blotting, TA protein fate assays; yeast screen of TA proteins combined with mammalian validation Scientific reports Medium 28000760
2018 Get1/2 ER membrane insertase complex is required for efficient mitophagy during prolonged respiratory growth in yeast. This requirement is independent of Get3 (the cytosolic ATPase), as Get3-deficient cells show only slight mitophagy defects, suggesting that Get1/2-dependent TA protein(s) or the Get1/2 complex itself acts specifically in the mitophagy pathway downstream of Atg32. Yeast deletion mutants of get1/2 and get3; mitophagy assays during respiratory growth; Atg32 localization and expression analysis Biochemical and biophysical research communications Medium 29673596
2003 GET1/GRHL3 protein localizes to the nucleus, binds Grainyhead DNA-binding sites, homodimerizes via a short C-terminal domain, and contains a transactivation domain (aa 100–190) sufficient to confer transactivation to a heterologous GAL4 DBD. The DNA-binding domain maps to the region homologous to Drosophila Grainyhead DBD. GET1 also contains repression domains, consistent with dual activator/repressor function. GET1 was identified as an LMO-4 interacting partner by yeast two-hybrid. Yeast two-hybrid screen for LMO-4 partners; reporter assays for transactivation; dimerization assays; nuclear localization by cell imaging; Grainyhead site EMSA Developmental dynamics Medium 12666198
2008 Get1/Grhl3 acts upstream of TGFα in the EGFR/ERK pathway during eyelid closure: Get1 knockout mice have reduced TGFα expression, reduced phospho-EGFR and phospho-ERK at the leading edge, and defective F-actin polymerization and filopodia formation. TGFα treatment in organ culture rescued cell shape changes and leading edge formation in Get1−/− eyelids. Get1 knockout mouse analysis; immunostaining for phospho-EGFR, phospho-ERK, F-actin; organ culture TGFα rescue experiment Developmental biology Medium 18485343
2009 Get1/Grhl3 directly binds the uroplakin II promoter in urothelial cells and activates its transcription, driving urothelial differentiation and apical membrane specialization. This binding is regulated by histone modifications. Get1 knockout mice have defective bladder epithelial barrier due to failure of uroplakin-dependent apical membrane specialization. Get1 knockout mouse; genome-wide expression profiling; ChIP demonstrating Get1 binding to uroplakin II promoter; histone modification analysis The EMBO journal Medium 19494835
2012 GRHL3/GET1 recruits the Trithorax complex to a subset of epidermal differentiation genes, activating their expression. GET1 cooperates with Trithorax group members both for genes that are Polycomb-repressed in progenitors and for Polycomb-independent differentiation genes. Genome-wide chromatin analysis, co-recruitment assays; Grhl3 knockout epidermis analysis PLoS genetics Medium 22829784
2012 Grhl3/Get1 binds and represses the miR-21 promoter in the epidermis, establishing a regulatory loop. Loss of Grhl3 increases miR-21 levels, which in Ras-transformed keratinocytes leads to enhanced downregulation of MSH2 and other miR-21 targets, in part through downregulation of the RNA-binding protein DND1 during transformation. miRNA profiling in Grhl3−/− skin; ChIP showing Grhl3 binding to miR-21 promoter; reporter and overexpression assays; subcutaneous tumor formation assay Oncogene Medium 22614019
1990 The Wrb antigen on glycophorin A (GPA) requires the interaction of GPA with band 3 (SLC4A1) for its expression on erythrocytes. Wrb antibodies immunoprecipitate both band 3 and glycophorin A together, while monospecific antibodies to each protein precipitate only their cognate antigen, indicating a direct GPA–band 3 complex underlies Wrb antigen expression. Radioimmunoassay with monoclonal anti-Wrb antibodies; co-immunoprecipitation of erythrocyte membrane proteins Blood Medium 2383660

Source papers

Stage 0 corpus · 31 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2014 The Get1/2 transmembrane complex is an endoplasmic-reticulum membrane protein insertase. Nature 106 25043001
2011 WRB is the receptor for TRC40/Asna1-mediated insertion of tail-anchored proteins into the ER membrane. Journal of cell science 98 21444755
2012 GRHL3/GET1 and trithorax group members collaborate to activate the epidermal progenitor differentiation program. PLoS genetics 84 22829784
1983 The Wrb antigen, a receptor for Plasmodium falciparum malaria, is located on a helical region of the major membrane sialoglycoprotein of human red blood cells. The Biochemical journal 75 6342608
1976 Anti-Wrb, and other autoantibodies responsible for positive direct antiglobulin tests in 150 individuals. British journal of haematology 71 952768
2003 Identification and characterization of Grainyhead-like epithelial transactivator (GET-1), a novel mammalian Grainyhead-like factor. Developmental dynamics : an official publication of the American Association of Anatomists 69 12666198
2009 The epidermal differentiation-associated Grainyhead gene Get1/Grhl3 also regulates urothelial differentiation. The EMBO journal 68 19494835
1990 Relationship of the human erythrocyte Wrb antigen to an interaction between glycophorin A and band 3. Blood 65 2383660
2012 The Grainyhead transcription factor Grhl3/Get1 suppresses miR-21 expression and tumorigenesis in skin: modulation of the miR-21 target MSH2 by RNA-binding protein DND1. Oncogene 62 22614019
2014 WRB and CAML are necessary and sufficient to mediate tail-anchored protein targeting to the ER membrane. PloS one 55 24392163
2008 Grainyhead-like factor Get1/Grhl3 regulates formation of the epidermal leading edge during eyelid closure. Developmental biology 53 18485343
1986 High frequency antigens of human erythrocyte membrane sialoglycoproteins, III. Studies on the EnaFR, Wrb and Wra antigens. Biological chemistry Hoppe-Seyler 49 3539140
2016 Tryptophan-rich basic protein (WRB) mediates insertion of the tail-anchored protein otoferlin and is required for hair cell exocytosis and hearing. The EMBO journal 48 27458190
2016 Mice lacking WRB reveal differential biogenesis requirements of tail-anchored proteins in vivo. Scientific reports 35 28000760
2017 Tail-Anchored Protein Insertion by a Single Get1/2 Heterodimer. Cell reports 26 28877464
2016 Mutation of wrb, a Component of the Guided Entry of Tail-Anchored Protein Pathway, Disrupts Photoreceptor Synapse Structure and Function. Investigative ophthalmology & visual science 25 27273592
2012 Get1 stabilizes an open dimer conformation of get3 ATPase by binding two distinct interfaces. Journal of molecular biology 24 22684149
2015 The zebrafish pinball wizard gene encodes WRB, a tail-anchored-protein receptor essential for inner-ear hair cells and retinal photoreceptors. The Journal of physiology 23 26593130
1994 Comparative immunochemical analysis of Wra and Wrb red cell antigens. Vox sanguinis 18 7801617
2019 The WRB Subunit of the Get3 Receptor is Required for the Correct Integration of its Partner CAML into the ER. Scientific reports 17 31417168
1985 Phospholipid dependence of Wrb antigen expression in human erythrocyte membranes. Vox sanguinis 14 4082531
2023 linc-mipep and linc-wrb encode micropeptides that regulate chromatin accessibility in vertebrate-specific neural cells. eLife 13 37191016
1999 Glycophorin A mutation Ala65 --> Pro gives rise to a novel pair of MNS alleles ENEP (MNS39) and HAG (MNS41) and altered Wrb expression: direct evidence for GPA/band 3 interaction necessary for normal Wrb expression. Transfusion medicine (Oxford, England) 13 10354388
2018 The ER membrane insertase Get1/2 is required for efficient mitophagy in yeast. Biochemical and biophysical research communications 12 29673596
1988 Evidence that Wra and Wrb are antithetical. Transfusion 12 3281333
2010 Miltenberger blood group antigen subtype III (Mi.III) supports Wr(b) expression. Vox sanguinis 9 21029112
1978 Further studies on the relationship of anti-Ena and anti-Wrb in warm autoimmune hemolytic anemia. Transfusion 9 705866
2022 The Get1/2 insertase forms a channel to mediate the insertion of tail-anchored proteins into the ER. Cell reports 6 36640319
2021 Subunit cooperation in the Get1/2 receptor promotes tail-anchored membrane protein insertion. The Journal of cell biology 4 34614151
2024 Membrane Interactions of GET1 and GET2 Facilitate Fiber Cell Initiation through the Guided Entry of the TA Protein Pathway in Cotton. Journal of agricultural and food chemistry 1 39467771
1987 Effect of pentoxifylline on Wrb antigen. Transfusion 0 3603661

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