{"gene":"RER1","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":1995,"finding":"Rer1p is a four-transmembrane-domain hydrophobic protein localized to the early Golgi apparatus (co-localizing with Ypt1p by immunofluorescence and co-fractionating with Och1p), where it functions to retrieve Sec12p that has escaped the ER static retention system back from the Golgi to the ER.","method":"Immunofluorescence microscopy with HA-tagged Rer1p, subcellular fractionation, double staining with Golgi marker Ypt1p, sec7 mutant accumulation assay, rer1 null mutant analysis","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (immunofluorescence, fractionation, genetic mutants), foundational characterization paper with clear functional readout","pmids":["8589449"],"is_preprint":false},{"year":1997,"finding":"Human Rer1 is a 196-amino-acid, 23 kDa protein with four predicted transmembrane domains (W-topology, both N- and C-termini cytosolic) that localizes to the Golgi apparatus and ER-Golgi interface, and functionally complements deletion of yeast RER1, reducing mislocalization of the Sec12 reporter protein.","method":"Reverse PCR cloning, myc-tag immunofluorescence, immunoelectron microscopy of cryosections, brefeldin A treatment, complementation assay in S. cerevisiae rer1Δ","journal":"European journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization by immunoelectron microscopy plus functional complementation across species, multiple orthogonal methods","pmids":["9309388"],"is_preprint":false},{"year":2007,"finding":"Mammalian Rer1 directly binds unassembled Pen2 (a γ-secretase subunit) via the first transmembrane domain of Pen2, with a conserved asparagine in that domain required for binding; this interaction retains/retrieves unassembled Pen2 in the ER, and Rer1 is the first identified interaction partner of mammalian transmembrane-based retention/retrieval signals.","method":"Co-immunoprecipitation, Rer1 downregulation (increased Pen2 surface localization), Rer1 overexpression (stabilizes unassembled Pen2), TMD mutagenesis (asparagine mutation abolishes binding)","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding with mutagenesis identifying the critical residue, gain- and loss-of-function experiments with defined readout, single lab but multiple orthogonal methods","pmids":["17668005"],"is_preprint":false},{"year":2010,"finding":"Rer1 localizes to the early secretory pathway in myoblasts and skeletal muscle, retains unassembled nicotinic acetylcholine receptor (nAChR) α-subunits in the ER, and its knockdown causes unassembled α-subunits to escape to the plasma membrane and lysosomes where they are degraded, reducing fully assembled surface receptor and producing smaller neuromuscular junctions in vivo.","method":"siRNA knockdown in C2C12 cells, surface biotinylation, immunofluorescence, in vivo Rer1 knockdown and heterozygous knockout mice, NMJ morphometry","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function in cell culture and in vivo mouse models with defined cellular and morphological phenotypes, multiple orthogonal methods","pmids":["21187406"],"is_preprint":false},{"year":2012,"finding":"RER1 associates with γ-secretase in early secretory compartments and retains it there; RER1 overexpression decreases γ-secretase and APP at the cell surface and reduces Aβ secretion, while RER1 knockdown increases surface γ-secretase, increases mature APP, and increases Aβ secretion.","method":"Co-immunoprecipitation, RER1 overexpression and siRNA knockdown, surface biotinylation, Aβ ELISA, APP maturation analysis by Western blot","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal gain- and loss-of-function with multiple orthogonal readouts (Co-IP, surface biotinylation, secretion assay)","pmids":["23043097"],"is_preprint":false},{"year":2012,"finding":"The E3 ubiquitin ligase synoviolin (Syvn) interacts with Rer1 in the ER, ubiquitinates Rer1, and targets it for proteasomal or lysosomal degradation; Syvn knockout fibroblasts accumulate higher Rer1 levels, leading to decreased mature nicastrin (NCT) at the plasma membrane and reduced γ-secretase complex levels.","method":"Co-immunoprecipitation, dominant-negative Syvn overexpression, Syvn-RNAi, Syvn knockout mouse fibroblasts, ubiquitination assay, Western blot for Rer1 and NCT localization","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — identified writer enzyme (Syvn), ubiquitination demonstrated biochemically, validated in knockout cells with multiple readouts","pmids":["23129766"],"is_preprint":false},{"year":2014,"finding":"Rer1 acts as a Golgi-localized sorting receptor that interacts with both wild-type and mutant PMP22 (including CMT disease-associated L16P and G150D); loss of Rer1 partly releases PMP22(L16P) from the ER, and simultaneous knockdown of Rer1 and the ER chaperone calnexin produces more pronounced release, indicating that CMT PMP22(L16P) is trapped by both calnexin-dependent ER retention and Rer1-mediated Golgi retrieval.","method":"siRNA knockdown of Rer1 and calnexin (single and double), co-immunoprecipitation of Rer1 with wild-type and mutant PMP22, ER/Golgi localization assays","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP of interaction plus epistatic double-knockdown experiment dissecting two parallel retention mechanisms","pmids":["25385046"],"is_preprint":false},{"year":2017,"finding":"RER1 overexpression decreases levels of wild-type and disease-mutant (A30P, A53T, E46K) α-synuclein via the ubiquitin-proteasome system, an effect dependent on the C-terminal ER retention/retrieval domain of RER1 (RER1Δ25 mutant has attenuated effect); RER1 co-localizes with α-synuclein-positive Lewy bodies in human brain and appears to interact with the ubiquitin ligase NEDD4.","method":"RER1 and RER1Δ25 overexpression in HEK293 and H4 cells, proteasomal and autophagy inhibitors, co-immunoprecipitation with NEDD4, immunofluorescence co-localization in human brain tissue","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — overexpression with domain mutant and inhibitor studies, Co-IP with NEDD4 is single pulldown, mechanistic pathway placement is partial","pmids":["28877262"],"is_preprint":false},{"year":2017,"finding":"PC-specific deletion of Rer1 in mice causes age-dependent Purkinje cell degeneration, severe deficits in spontaneous action potential generation, and decreased surface density of voltage-gated sodium channels (Nav); whole-brain Rer1 deletion strongly down-regulates Nav1.6 and Nav1.1 protein levels without affecting Cav2.1, Kv3.3, or Kv7.2, indicating Rer1 controls assembly and transport of Nav1.1 and Nav1.6.","method":"Conditional (PC-specific) and whole-brain Rer1 knockout mice, electrophysiological recordings (spontaneous firing, resurgent currents), Western blot for channel proteins, behavioral tests (beam walk, ladder climbing, gait)","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockout with electrophysiological and biochemical readouts, substrate selectivity established by comparing multiple channel proteins","pmids":["28117367"],"is_preprint":false},{"year":2018,"finding":"Rer1 is required in the developing mouse cerebral cortex for sufficient cell-surface expression and activity of the γ-secretase complex; Rer1 depletion causes a subpopulation of γ-secretase complexes and components to be mis-trafficked to and degraded in lysosomes, reducing surface γ-secretase, lowering Notch signaling, decreasing neural stem cell numbers, and causing cortical malformation.","method":"Cortex-specific Rer1 knockout mice, γ-secretase activity assays, Notch signaling reporter assays, lysosomal trafficking assays, immunohistochemistry for neural stem cell markers","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo conditional knockout with mechanistic pathway placement (Rer1 → γ-secretase surface levels → Notch signaling → neural stem cell maintenance), multiple orthogonal readouts","pmids":["30260951"],"is_preprint":false},{"year":2022,"finding":"NEDD4-2 (an E3 ubiquitin ligase) interacts with RER1 via its STPY motif (residues 36-39 of RER1), ubiquitinates RER1, and targets it for proteasomal degradation; Nedd4-2 haploinsufficiency impairs RER1 ubiquitination, elevates RER1 levels in mouse brain, and increases ER retention of the GABA-A receptor α1 subunit, which is validated as an Rer1 cargo.","method":"Nedd4-2+/- mice, co-immunoprecipitation, NEDD4-2 knockdown/overexpression, RER1 STPY motif mutagenesis, immunoprecipitation-mass spectrometry interactome screen, Endo-H digestion to assess ER retention of GABA-A α1","journal":"Frontiers in molecular neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — identified writer (NEDD4-2), mapped binding motif by mutagenesis, validated cargo interaction by Endo-H, multiple orthogonal methods in cells and mice","pmids":["35832397"],"is_preprint":false},{"year":2023,"finding":"Glucocorticoid (cortisol) transcriptionally represses RER1 by directing the glucocorticoid receptor (GR) to bind directly to the RER1 promoter; reduced Rer1 allows presenilin 1 (PSEN1) to mature and enter the endocytic/secretory pathway, increasing γ-secretase activity at the ER-mitochondria associated membrane (MAM) and enhancing Aβ production; RER1 overexpression reverses mitochondrial Aβ accumulation and restores mitochondrial respiratory function.","method":"ChIP (GR binding to RER1 promoter), RER1 overexpression and knockdown in SH-SY5Y cells and ICR mice, PSEN1 localization assay (MAM fractionation), γ-secretase activity assay, mitochondrial respiration measurement, spatial memory testing in corticosterone-treated mice","journal":"Redox biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP identifies transcriptional repressor, gain- and loss-of-function with mechanistic pathway placement, validated in both cell and in vivo mouse models","pmids":["37494768"],"is_preprint":false},{"year":2024,"finding":"Unassembled DAP12 interacts with RER1 and is retained in early secretory compartments (ER and ERGIC), preventing its transport to the plasma membrane; deletion of endogenous RER1 decreases functional TREM2-DAP12 complex expression, impairs membrane-proximal signaling, and almost completely inhibits phagocytic activity in THP-1 macrophage-like cells.","method":"Co-immunoprecipitation of DAP12 and RER1, endogenous RER1 CRISPR knockout in THP-1 cells, surface expression assays, phagocytosis assay, signaling assays","journal":"Cellular and molecular life sciences : CMLS","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding demonstrated by Co-IP, endogenous knockout with multiple functional readouts (complex assembly, signaling, phagocytosis)","pmids":["39008111"],"is_preprint":false},{"year":2024,"finding":"Loss of Rer1 in Drosophila wing epithelium leads to proteotoxic stress and PERK-mediated phosphorylation of eIF2α; rer1 mutant cells are recognized as 'losers' and eliminated by cell competition; Myc overexpression upregulates Rer1 levels, and increased Rer1 provides cytoprotection by alleviating proteotoxic stress to support Myc-driven overgrowth.","method":"Drosophila clonal analysis (rer1 mutant clones), immunostaining for p-eIF2α (PERK pathway marker), genetic epistasis between Rer1 and Myc, cell competition assay in wing epithelium","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function with PERK pathway readout and epistasis in Drosophila, single lab, mechanistic link to proteostasis is indirect","pmids":["38408084"],"is_preprint":false},{"year":2025,"finding":"The HSD17B7 p.E182* mutation disrupts interaction between HSD17B7 and the ER retention receptor RER1, leading to aberrant subcellular localization of HSD17B7 and altered cholesterol distribution, thereby impairing hair cell function.","method":"Co-immunoprecipitation of HSD17B7 and RER1, mutant vs. wild-type comparison, subcellular localization assay, cholesterol distribution assay in HEI-OC1 cells and zebrafish","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP in preprint, indirect evidence that RER1 interaction controls HSD17B7 localization, not yet peer-reviewed","pmids":["bio_10.1101_2025.07.15.665034"],"is_preprint":true}],"current_model":"RER1 is a four-transmembrane-domain sorting receptor localized to the cis-Golgi and ERGIC that retrieves escaped or unassembled membrane proteins back to the ER by directly binding transmembrane domain-based retention signals; its substrates include unassembled subunits of γ-secretase (Pen2, nicastrin, PSEN1), nicotinic acetylcholine receptor α-subunits, voltage-gated sodium channels Nav1.1/1.6, DAP12, GABA-A receptor α1, and PMP22 mutants; RER1 itself is regulated by ubiquitin-mediated proteasomal degradation executed by synoviolin (Syvn) and NEDD4/NEDD4-2, and its transcription is repressed by glucocorticoid receptor binding to its promoter, with downstream consequences for γ-secretase trafficking, Notch signaling, Aβ production, immune receptor complex assembly, and phagocytosis."},"narrative":{"mechanistic_narrative":"RER1 is a four-transmembrane-domain sorting receptor of the early secretory pathway that retrieves escaped or unassembled membrane proteins from the cis-Golgi/ERGIC back to the ER, originally defined in yeast by its retrieval of the ER protein Sec12p that escapes static retention [PMID:8589449]; the human ortholog adopts the same W-topology with cytosolic N- and C-termini, localizes to the Golgi/ER-Golgi interface, and functionally complements yeast rer1Δ [PMID:9309388]. RER1 recognizes transmembrane-domain-based retention/retrieval signals directly, as established by its binding to unassembled γ-secretase subunit Pen2 through Pen2's first transmembrane domain and a conserved asparagine residue [PMID:17668005]; through this quality-control activity it governs assembly and surface delivery of multiple multi-subunit membrane complexes, retaining unassembled γ-secretase to limit cell-surface enzyme and Aβ production [PMID:23043097], nicotinic acetylcholine receptor α-subunits to control neuromuscular junction formation [PMID:21187406], voltage-gated sodium channels Nav1.1/Nav1.6 for Purkinje cell excitability [PMID:28117367], and DAP12 to enable TREM2-DAP12 complex assembly, signaling, and macrophage phagocytosis [PMID:39008111]. In the developing cortex RER1 sustains surface γ-secretase activity, Notch signaling, and neural stem cell maintenance, with its loss diverting γ-secretase components to lysosomal degradation [PMID:30260951]. RER1 abundance is controlled by ubiquitin-mediated degradation through the E3 ligases synoviolin/SYVN1 [PMID:23129766] and NEDD4-2, the latter binding an RER1 STPY motif and whose loss elevates RER1 and increases ER retention of GABA-A receptor α1 [PMID:35832397], and by transcriptional repression via glucocorticoid receptor binding to the RER1 promoter, which raises PSEN1 maturation and γ-secretase activity at ER-mitochondria membranes [PMID:37494768]. RER1 also engages disease-associated cargoes including CMT-mutant PMP22, which it traps in parallel with calnexin-dependent ER retention [PMID:25385046].","teleology":[{"year":1995,"claim":"Established that a dedicated retrieval receptor returns escaped ER residents from the Golgi, answering how proteins lacking robust static retention are kept in the ER.","evidence":"Immunofluorescence, fractionation, and rer1 null analysis in S. cerevisiae showing Rer1p retrieves escaped Sec12p","pmids":["8589449"],"confidence":"High","gaps":["Molecular signal recognized by Rer1p not defined","No mammalian ortholog characterized yet"]},{"year":1997,"claim":"Showed the retrieval function is conserved in humans, defining RER1 topology and cross-species functional equivalence.","evidence":"Cloning, immunoelectron microscopy, and complementation of yeast rer1Δ by human RER1","pmids":["9309388"],"confidence":"High","gaps":["Endogenous mammalian cargoes unknown","Recognition mechanism unresolved"]},{"year":2007,"claim":"Defined the molecular basis of recognition by demonstrating direct binding of RER1 to a transmembrane-domain retention signal, establishing it as a quality-control receptor for unassembled subunits.","evidence":"Co-IP, TMD mutagenesis (asparagine), and gain/loss-of-function with Pen2 in mammalian cells","pmids":["17668005"],"confidence":"High","gaps":["Structural detail of TMD recognition absent","Generality across other substrates not yet tested"]},{"year":2010,"claim":"Extended RER1 quality control to a physiological multi-subunit receptor, linking subunit retention to organ-level assembly and function.","evidence":"siRNA in C2C12, surface biotinylation, and in vivo knockdown/knockout mice with NMJ morphometry","pmids":["21187406"],"confidence":"High","gaps":["Whether RER1 directly binds the α-subunit TMD not shown","Retrieval versus retention not distinguished"]},{"year":2012,"claim":"Connected RER1 retention activity to γ-secretase trafficking and amyloidogenesis, defining a disease-relevant output of the receptor.","evidence":"Co-IP, reciprocal overexpression/knockdown, surface biotinylation, and Aβ ELISA","pmids":["23043097"],"confidence":"High","gaps":["Which assembly intermediates RER1 acts on not resolved","In vivo relevance not addressed in this study"]},{"year":2012,"claim":"Identified the first regulator of RER1 abundance, showing an ER E3 ligase ubiquitinates RER1 and thereby tunes downstream γ-secretase assembly.","evidence":"Co-IP, ubiquitination assay, Syvn knockout fibroblasts with nicastrin readouts","pmids":["23129766"],"confidence":"High","gaps":["Proteasomal versus lysosomal route not fully separated","Signals triggering RER1 turnover unknown"]},{"year":2014,"claim":"Showed RER1 cooperates with chaperone-based ER retention to trap disease-mutant membrane proteins, dissecting two parallel quality-control layers.","evidence":"Co-IP and single/double siRNA of Rer1 and calnexin with PMP22 mutants","pmids":["25385046"],"confidence":"High","gaps":["Therapeutic consequence of releasing trapped PMP22 not tested","Direct TMD interaction not mapped"]},{"year":2017,"claim":"Implicated RER1 in degradation of α-synuclein and linked it to a second E3 ligase, broadening its role in proteostasis.","evidence":"Overexpression with C-terminal domain mutant, inhibitor studies, NEDD4 Co-IP, and Lewy body co-localization","pmids":["28877262"],"confidence":"Medium","gaps":["NEDD4 interaction rests on a single pulldown","Mechanistic placement of RER1 in degradation pathway partial"]},{"year":2017,"claim":"Established substrate-selective control of ion channel surface density in vivo, showing RER1 shapes neuronal excitability.","evidence":"Conditional and whole-brain Rer1 knockout mice with electrophysiology and channel-protein Westerns","pmids":["28117367"],"confidence":"High","gaps":["Direct RER1-Nav binding not demonstrated","Basis of selectivity for Nav1.1/1.6 over other channels unexplained"]},{"year":2018,"claim":"Placed RER1 in a developmental signaling cascade, demonstrating that its control of surface γ-secretase feeds Notch signaling and stem cell maintenance.","evidence":"Cortex-specific knockout mice with γ-secretase activity, Notch reporter, and lysosomal trafficking assays","pmids":["30260951"],"confidence":"High","gaps":["Which γ-secretase components are diverted to lysosomes not fully resolved","Direct versus indirect Notch effect not separated"]},{"year":2022,"claim":"Defined a second ubiquitin pathway controlling RER1 via a mapped STPY motif and validated a new cargo, linking RER1 turnover to receptor ER retention.","evidence":"Nedd4-2+/- mice, Co-IP, STPY mutagenesis, IP-MS interactome, and Endo-H assay for GABA-A α1","pmids":["35832397"],"confidence":"High","gaps":["Relative contributions of SYVN1 versus NEDD4-2 not compared","Functional consequence of GABA-A α1 retention not measured"]},{"year":2023,"claim":"Identified transcriptional regulation of RER1 by glucocorticoid signaling, connecting stress hormones to γ-secretase activity and mitochondrial amyloid pathology.","evidence":"ChIP of GR on RER1 promoter, gain/loss-of-function in cells and mice, MAM fractionation, and respiration/memory assays","pmids":["37494768"],"confidence":"High","gaps":["How RER1 loss localizes PSEN1 maturation to MAM not mechanistically detailed","GR co-regulators at the promoter unidentified"]},{"year":2024,"claim":"Extended RER1 quality control to innate immune receptor assembly, showing its retention of unassembled DAP12 is required for phagocytic function.","evidence":"Co-IP, endogenous CRISPR knockout in THP-1 cells, surface, signaling, and phagocytosis assays","pmids":["39008111"],"confidence":"High","gaps":["TMD signal in DAP12 recognized by RER1 not mapped","Whether TREM2 itself is a cargo not tested"]},{"year":2024,"claim":"Linked RER1 to organismal proteostasis and cell competition, positioning it as a Myc-induced cytoprotective factor against ER stress.","evidence":"Drosophila clonal analysis, p-eIF2α staining, and Rer1-Myc genetic epistasis in wing epithelium","pmids":["38408084"],"confidence":"Medium","gaps":["Link to proteostasis is indirect","Specific cargoes underlying proteotoxic stress not identified"]},{"year":2025,"claim":"Proposed RER1 controls localization of a sterol-metabolizing enzyme relevant to hearing, expanding its cargo repertoire toward lipid homeostasis.","evidence":"Co-IP of HSD17B7 with RER1, mutant comparison, and cholesterol/localization assays in cells and zebrafish (preprint)","pmids":["bio_10.1101_2025.07.15.665034"],"confidence":"Low","gaps":["Single Co-IP in a non-peer-reviewed preprint","Direct interaction not independently confirmed","Mechanism of cholesterol mislocalization unresolved"]},{"year":null,"claim":"How RER1 structurally discriminates among diverse transmembrane retention signals and how cargo selection is regulated across cell types remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural model of RER1-cargo TMD recognition","Rules governing substrate selectivity across tissues unknown","Coordination between transcriptional and post-translational regulation of RER1 not integrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0038024","term_label":"cargo receptor activity","supporting_discovery_ids":[0,2,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,4,12]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[1,2,5]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,2,4]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[5,10]}],"complexes":[],"partners":["PSEN1","PSENEN","NCSTN","SYVN1","NEDD4L","PMP22","TYROBP","NEDD4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O15258","full_name":"Protein RER1","aliases":[],"length_aa":196,"mass_kda":23.0,"function":"Involved in the retrieval of endoplasmic reticulum membrane proteins from the early Golgi compartment","subcellular_location":"Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/O15258/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RER1","classification":"Not Classified","n_dependent_lines":161,"n_total_lines":1208,"dependency_fraction":0.13327814569536423},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000157916","cell_line_id":"CID000968","localizations":[{"compartment":"golgi","grade":3},{"compartment":"vesicles","grade":3}],"interactors":[{"gene":"NDUFA3","stoichiometry":10.0},{"gene":"PGRMC1","stoichiometry":10.0},{"gene":"GORASP2","stoichiometry":4.0},{"gene":"LMAN2","stoichiometry":4.0},{"gene":"HSP90B1","stoichiometry":4.0},{"gene":"COPB2","stoichiometry":0.2},{"gene":"YIF1B","stoichiometry":0.2},{"gene":"ACADM","stoichiometry":0.2},{"gene":"SCFD1","stoichiometry":0.2},{"gene":"TRAP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000968","total_profiled":1310},"omim":[{"mim_id":"620048","title":"RETENTION IN ENDOPLASMIC RETICULUM SORTING RECEPTOR 1; RER1","url":"https://www.omim.org/entry/620048"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RER1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O15258","domains":[{"cath_id":"-","chopping":"48-93_110-171","consensus_level":"high","plddt":88.9668,"start":48,"end":171}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O15258","model_url":"https://alphafold.ebi.ac.uk/files/AF-O15258-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O15258-F1-predicted_aligned_error_v6.png","plddt_mean":78.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RER1","jax_strain_url":"https://www.jax.org/strain/search?query=RER1"},"sequence":{"accession":"O15258","fasta_url":"https://rest.uniprot.org/uniprotkb/O15258.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O15258/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O15258"}},"corpus_meta":[{"pmid":"8589449","id":"PMC_8589449","title":"Membrane protein retrieval from the Golgi apparatus to the endoplasmic reticulum (ER): characterization of the RER1 gene product as a component involved in ER localization of Sec12p.","date":"1995","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/8589449","citation_count":94,"is_preprint":false},{"pmid":"17668005","id":"PMC_17668005","title":"Endoplasmic reticulum retention of the gamma-secretase complex component Pen2 by Rer1.","date":"2007","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/17668005","citation_count":72,"is_preprint":false},{"pmid":"21187406","id":"PMC_21187406","title":"Sorting receptor Rer1 controls surface expression of muscle acetylcholine receptors by ER retention of unassembled alpha-subunits.","date":"2010","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/21187406","citation_count":45,"is_preprint":false},{"pmid":"9309388","id":"PMC_9309388","title":"Human Rer1 is localized to the Golgi apparatus and complements the deletion of the homologous Rer1 protein of Saccharomyces cerevisiae.","date":"1997","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/9309388","citation_count":40,"is_preprint":false},{"pmid":"25385046","id":"PMC_25385046","title":"Rer1 and calnexin regulate endoplasmic reticulum retention of a peripheral myelin protein 22 mutant that causes type 1A Charcot-Marie-Tooth disease.","date":"2014","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/25385046","citation_count":38,"is_preprint":false},{"pmid":"30630537","id":"PMC_30630537","title":"RER1 enhances carcinogenesis and stemness of pancreatic cancer under hypoxic environment.","date":"2019","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/30630537","citation_count":35,"is_preprint":false},{"pmid":"23043097","id":"PMC_23043097","title":"Retention in endoplasmic reticulum 1 (RER1) modulates amyloid-β (Aβ) production by altering trafficking of γ-secretase and amyloid precursor protein (APP).","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23043097","citation_count":30,"is_preprint":false},{"pmid":"28877262","id":"PMC_28877262","title":"The ER retention protein RER1 promotes alpha-synuclein degradation via the proteasome.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28877262","citation_count":22,"is_preprint":false},{"pmid":"32873699","id":"PMC_32873699","title":"Bring it back, bring it back, don't take it away from me - the sorting receptor RER1.","date":"2020","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/32873699","citation_count":18,"is_preprint":false},{"pmid":"23129766","id":"PMC_23129766","title":"The ubiquitin ligase synoviolin up-regulates amyloid β production by targeting a negative regulator of γ-secretase, Rer1, for degradation.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23129766","citation_count":16,"is_preprint":false},{"pmid":"28117367","id":"PMC_28117367","title":"The sorting receptor Rer1 controls Purkinje cell function via voltage gated sodium channels.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28117367","citation_count":13,"is_preprint":false},{"pmid":"30260951","id":"PMC_30260951","title":"Rer1-mediated quality control system is required for neural stem cell maintenance during cerebral cortex development.","date":"2018","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30260951","citation_count":13,"is_preprint":false},{"pmid":"37494768","id":"PMC_37494768","title":"Glucocorticoid enhances presenilin1-dependent Aβ production at ER's mitochondrial-associated membrane by downregulating Rer1 in neuronal cells.","date":"2023","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/37494768","citation_count":12,"is_preprint":false},{"pmid":"39008111","id":"PMC_39008111","title":"DAP12 interacts with RER1 and is retained in the secretory pathway before assembly with TREM2.","date":"2024","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/39008111","citation_count":11,"is_preprint":false},{"pmid":"38408084","id":"PMC_38408084","title":"Maintenance of proteostasis by Drosophila Rer1 is essential for competitive cell survival and Myc-driven overgrowth.","date":"2024","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38408084","citation_count":4,"is_preprint":false},{"pmid":"35832397","id":"PMC_35832397","title":"Nedd4-2 Haploinsufficiency in Mice Impairs the Ubiquitination of Rer1 and Increases the Susceptibility to Endoplasmic Reticulum Stress and Seizures.","date":"2022","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/35832397","citation_count":3,"is_preprint":false},{"pmid":"40802025","id":"PMC_40802025","title":"RER1 regulates lipid metabolism in monocytes and macrophages.","date":"2025","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/40802025","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.07.15.665034","title":"HSD17B7 is required for the function of sensory hair cells by regulating cholesterol synthesis","date":"2025-07-18","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.15.665034","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11111,"output_tokens":4490,"usd":0.050341,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12434,"output_tokens":4483,"usd":0.087123,"stage2_stop_reason":"end_turn"},"total_usd":0.137464,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"Rer1p is a four-transmembrane-domain hydrophobic protein localized to the early Golgi apparatus (co-localizing with Ypt1p by immunofluorescence and co-fractionating with Och1p), where it functions to retrieve Sec12p that has escaped the ER static retention system back from the Golgi to the ER.\",\n      \"method\": \"Immunofluorescence microscopy with HA-tagged Rer1p, subcellular fractionation, double staining with Golgi marker Ypt1p, sec7 mutant accumulation assay, rer1 null mutant analysis\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (immunofluorescence, fractionation, genetic mutants), foundational characterization paper with clear functional readout\",\n      \"pmids\": [\"8589449\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Human Rer1 is a 196-amino-acid, 23 kDa protein with four predicted transmembrane domains (W-topology, both N- and C-termini cytosolic) that localizes to the Golgi apparatus and ER-Golgi interface, and functionally complements deletion of yeast RER1, reducing mislocalization of the Sec12 reporter protein.\",\n      \"method\": \"Reverse PCR cloning, myc-tag immunofluorescence, immunoelectron microscopy of cryosections, brefeldin A treatment, complementation assay in S. cerevisiae rer1Δ\",\n      \"journal\": \"European journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization by immunoelectron microscopy plus functional complementation across species, multiple orthogonal methods\",\n      \"pmids\": [\"9309388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mammalian Rer1 directly binds unassembled Pen2 (a γ-secretase subunit) via the first transmembrane domain of Pen2, with a conserved asparagine in that domain required for binding; this interaction retains/retrieves unassembled Pen2 in the ER, and Rer1 is the first identified interaction partner of mammalian transmembrane-based retention/retrieval signals.\",\n      \"method\": \"Co-immunoprecipitation, Rer1 downregulation (increased Pen2 surface localization), Rer1 overexpression (stabilizes unassembled Pen2), TMD mutagenesis (asparagine mutation abolishes binding)\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding with mutagenesis identifying the critical residue, gain- and loss-of-function experiments with defined readout, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"17668005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Rer1 localizes to the early secretory pathway in myoblasts and skeletal muscle, retains unassembled nicotinic acetylcholine receptor (nAChR) α-subunits in the ER, and its knockdown causes unassembled α-subunits to escape to the plasma membrane and lysosomes where they are degraded, reducing fully assembled surface receptor and producing smaller neuromuscular junctions in vivo.\",\n      \"method\": \"siRNA knockdown in C2C12 cells, surface biotinylation, immunofluorescence, in vivo Rer1 knockdown and heterozygous knockout mice, NMJ morphometry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function in cell culture and in vivo mouse models with defined cellular and morphological phenotypes, multiple orthogonal methods\",\n      \"pmids\": [\"21187406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RER1 associates with γ-secretase in early secretory compartments and retains it there; RER1 overexpression decreases γ-secretase and APP at the cell surface and reduces Aβ secretion, while RER1 knockdown increases surface γ-secretase, increases mature APP, and increases Aβ secretion.\",\n      \"method\": \"Co-immunoprecipitation, RER1 overexpression and siRNA knockdown, surface biotinylation, Aβ ELISA, APP maturation analysis by Western blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal gain- and loss-of-function with multiple orthogonal readouts (Co-IP, surface biotinylation, secretion assay)\",\n      \"pmids\": [\"23043097\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The E3 ubiquitin ligase synoviolin (Syvn) interacts with Rer1 in the ER, ubiquitinates Rer1, and targets it for proteasomal or lysosomal degradation; Syvn knockout fibroblasts accumulate higher Rer1 levels, leading to decreased mature nicastrin (NCT) at the plasma membrane and reduced γ-secretase complex levels.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative Syvn overexpression, Syvn-RNAi, Syvn knockout mouse fibroblasts, ubiquitination assay, Western blot for Rer1 and NCT localization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — identified writer enzyme (Syvn), ubiquitination demonstrated biochemically, validated in knockout cells with multiple readouts\",\n      \"pmids\": [\"23129766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Rer1 acts as a Golgi-localized sorting receptor that interacts with both wild-type and mutant PMP22 (including CMT disease-associated L16P and G150D); loss of Rer1 partly releases PMP22(L16P) from the ER, and simultaneous knockdown of Rer1 and the ER chaperone calnexin produces more pronounced release, indicating that CMT PMP22(L16P) is trapped by both calnexin-dependent ER retention and Rer1-mediated Golgi retrieval.\",\n      \"method\": \"siRNA knockdown of Rer1 and calnexin (single and double), co-immunoprecipitation of Rer1 with wild-type and mutant PMP22, ER/Golgi localization assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP of interaction plus epistatic double-knockdown experiment dissecting two parallel retention mechanisms\",\n      \"pmids\": [\"25385046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"RER1 overexpression decreases levels of wild-type and disease-mutant (A30P, A53T, E46K) α-synuclein via the ubiquitin-proteasome system, an effect dependent on the C-terminal ER retention/retrieval domain of RER1 (RER1Δ25 mutant has attenuated effect); RER1 co-localizes with α-synuclein-positive Lewy bodies in human brain and appears to interact with the ubiquitin ligase NEDD4.\",\n      \"method\": \"RER1 and RER1Δ25 overexpression in HEK293 and H4 cells, proteasomal and autophagy inhibitors, co-immunoprecipitation with NEDD4, immunofluorescence co-localization in human brain tissue\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — overexpression with domain mutant and inhibitor studies, Co-IP with NEDD4 is single pulldown, mechanistic pathway placement is partial\",\n      \"pmids\": [\"28877262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PC-specific deletion of Rer1 in mice causes age-dependent Purkinje cell degeneration, severe deficits in spontaneous action potential generation, and decreased surface density of voltage-gated sodium channels (Nav); whole-brain Rer1 deletion strongly down-regulates Nav1.6 and Nav1.1 protein levels without affecting Cav2.1, Kv3.3, or Kv7.2, indicating Rer1 controls assembly and transport of Nav1.1 and Nav1.6.\",\n      \"method\": \"Conditional (PC-specific) and whole-brain Rer1 knockout mice, electrophysiological recordings (spontaneous firing, resurgent currents), Western blot for channel proteins, behavioral tests (beam walk, ladder climbing, gait)\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockout with electrophysiological and biochemical readouts, substrate selectivity established by comparing multiple channel proteins\",\n      \"pmids\": [\"28117367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Rer1 is required in the developing mouse cerebral cortex for sufficient cell-surface expression and activity of the γ-secretase complex; Rer1 depletion causes a subpopulation of γ-secretase complexes and components to be mis-trafficked to and degraded in lysosomes, reducing surface γ-secretase, lowering Notch signaling, decreasing neural stem cell numbers, and causing cortical malformation.\",\n      \"method\": \"Cortex-specific Rer1 knockout mice, γ-secretase activity assays, Notch signaling reporter assays, lysosomal trafficking assays, immunohistochemistry for neural stem cell markers\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo conditional knockout with mechanistic pathway placement (Rer1 → γ-secretase surface levels → Notch signaling → neural stem cell maintenance), multiple orthogonal readouts\",\n      \"pmids\": [\"30260951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"NEDD4-2 (an E3 ubiquitin ligase) interacts with RER1 via its STPY motif (residues 36-39 of RER1), ubiquitinates RER1, and targets it for proteasomal degradation; Nedd4-2 haploinsufficiency impairs RER1 ubiquitination, elevates RER1 levels in mouse brain, and increases ER retention of the GABA-A receptor α1 subunit, which is validated as an Rer1 cargo.\",\n      \"method\": \"Nedd4-2+/- mice, co-immunoprecipitation, NEDD4-2 knockdown/overexpression, RER1 STPY motif mutagenesis, immunoprecipitation-mass spectrometry interactome screen, Endo-H digestion to assess ER retention of GABA-A α1\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — identified writer (NEDD4-2), mapped binding motif by mutagenesis, validated cargo interaction by Endo-H, multiple orthogonal methods in cells and mice\",\n      \"pmids\": [\"35832397\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Glucocorticoid (cortisol) transcriptionally represses RER1 by directing the glucocorticoid receptor (GR) to bind directly to the RER1 promoter; reduced Rer1 allows presenilin 1 (PSEN1) to mature and enter the endocytic/secretory pathway, increasing γ-secretase activity at the ER-mitochondria associated membrane (MAM) and enhancing Aβ production; RER1 overexpression reverses mitochondrial Aβ accumulation and restores mitochondrial respiratory function.\",\n      \"method\": \"ChIP (GR binding to RER1 promoter), RER1 overexpression and knockdown in SH-SY5Y cells and ICR mice, PSEN1 localization assay (MAM fractionation), γ-secretase activity assay, mitochondrial respiration measurement, spatial memory testing in corticosterone-treated mice\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP identifies transcriptional repressor, gain- and loss-of-function with mechanistic pathway placement, validated in both cell and in vivo mouse models\",\n      \"pmids\": [\"37494768\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Unassembled DAP12 interacts with RER1 and is retained in early secretory compartments (ER and ERGIC), preventing its transport to the plasma membrane; deletion of endogenous RER1 decreases functional TREM2-DAP12 complex expression, impairs membrane-proximal signaling, and almost completely inhibits phagocytic activity in THP-1 macrophage-like cells.\",\n      \"method\": \"Co-immunoprecipitation of DAP12 and RER1, endogenous RER1 CRISPR knockout in THP-1 cells, surface expression assays, phagocytosis assay, signaling assays\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding demonstrated by Co-IP, endogenous knockout with multiple functional readouts (complex assembly, signaling, phagocytosis)\",\n      \"pmids\": [\"39008111\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of Rer1 in Drosophila wing epithelium leads to proteotoxic stress and PERK-mediated phosphorylation of eIF2α; rer1 mutant cells are recognized as 'losers' and eliminated by cell competition; Myc overexpression upregulates Rer1 levels, and increased Rer1 provides cytoprotection by alleviating proteotoxic stress to support Myc-driven overgrowth.\",\n      \"method\": \"Drosophila clonal analysis (rer1 mutant clones), immunostaining for p-eIF2α (PERK pathway marker), genetic epistasis between Rer1 and Myc, cell competition assay in wing epithelium\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function with PERK pathway readout and epistasis in Drosophila, single lab, mechanistic link to proteostasis is indirect\",\n      \"pmids\": [\"38408084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The HSD17B7 p.E182* mutation disrupts interaction between HSD17B7 and the ER retention receptor RER1, leading to aberrant subcellular localization of HSD17B7 and altered cholesterol distribution, thereby impairing hair cell function.\",\n      \"method\": \"Co-immunoprecipitation of HSD17B7 and RER1, mutant vs. wild-type comparison, subcellular localization assay, cholesterol distribution assay in HEI-OC1 cells and zebrafish\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP in preprint, indirect evidence that RER1 interaction controls HSD17B7 localization, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.07.15.665034\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"RER1 is a four-transmembrane-domain sorting receptor localized to the cis-Golgi and ERGIC that retrieves escaped or unassembled membrane proteins back to the ER by directly binding transmembrane domain-based retention signals; its substrates include unassembled subunits of γ-secretase (Pen2, nicastrin, PSEN1), nicotinic acetylcholine receptor α-subunits, voltage-gated sodium channels Nav1.1/1.6, DAP12, GABA-A receptor α1, and PMP22 mutants; RER1 itself is regulated by ubiquitin-mediated proteasomal degradation executed by synoviolin (Syvn) and NEDD4/NEDD4-2, and its transcription is repressed by glucocorticoid receptor binding to its promoter, with downstream consequences for γ-secretase trafficking, Notch signaling, Aβ production, immune receptor complex assembly, and phagocytosis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RER1 is a four-transmembrane-domain sorting receptor of the early secretory pathway that retrieves escaped or unassembled membrane proteins from the cis-Golgi/ERGIC back to the ER, originally defined in yeast by its retrieval of the ER protein Sec12p that escapes static retention [#0]; the human ortholog adopts the same W-topology with cytosolic N- and C-termini, localizes to the Golgi/ER-Golgi interface, and functionally complements yeast rer1\\u0394 [#1]. RER1 recognizes transmembrane-domain-based retention/retrieval signals directly, as established by its binding to unassembled \\u03b3-secretase subunit Pen2 through Pen2's first transmembrane domain and a conserved asparagine residue [#2]; through this quality-control activity it governs assembly and surface delivery of multiple multi-subunit membrane complexes, retaining unassembled \\u03b3-secretase to limit cell-surface enzyme and A\\u03b2 production [#4], nicotinic acetylcholine receptor \\u03b1-subunits to control neuromuscular junction formation [#3], voltage-gated sodium channels Nav1.1/Nav1.6 for Purkinje cell excitability [#8], and DAP12 to enable TREM2-DAP12 complex assembly, signaling, and macrophage phagocytosis [#12]. In the developing cortex RER1 sustains surface \\u03b3-secretase activity, Notch signaling, and neural stem cell maintenance, with its loss diverting \\u03b3-secretase components to lysosomal degradation [#9]. RER1 abundance is controlled by ubiquitin-mediated degradation through the E3 ligases synoviolin/SYVN1 [#5] and NEDD4-2, the latter binding an RER1 STPY motif and whose loss elevates RER1 and increases ER retention of GABA-A receptor \\u03b11 [#10], and by transcriptional repression via glucocorticoid receptor binding to the RER1 promoter, which raises PSEN1 maturation and \\u03b3-secretase activity at ER-mitochondria membranes [#11]. RER1 also engages disease-associated cargoes including CMT-mutant PMP22, which it traps in parallel with calnexin-dependent ER retention [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established that a dedicated retrieval receptor returns escaped ER residents from the Golgi, answering how proteins lacking robust static retention are kept in the ER.\",\n      \"evidence\": \"Immunofluorescence, fractionation, and rer1 null analysis in S. cerevisiae showing Rer1p retrieves escaped Sec12p\",\n      \"pmids\": [\"8589449\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular signal recognized by Rer1p not defined\", \"No mammalian ortholog characterized yet\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Showed the retrieval function is conserved in humans, defining RER1 topology and cross-species functional equivalence.\",\n      \"evidence\": \"Cloning, immunoelectron microscopy, and complementation of yeast rer1\\u0394 by human RER1\",\n      \"pmids\": [\"9309388\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous mammalian cargoes unknown\", \"Recognition mechanism unresolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined the molecular basis of recognition by demonstrating direct binding of RER1 to a transmembrane-domain retention signal, establishing it as a quality-control receptor for unassembled subunits.\",\n      \"evidence\": \"Co-IP, TMD mutagenesis (asparagine), and gain/loss-of-function with Pen2 in mammalian cells\",\n      \"pmids\": [\"17668005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural detail of TMD recognition absent\", \"Generality across other substrates not yet tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Extended RER1 quality control to a physiological multi-subunit receptor, linking subunit retention to organ-level assembly and function.\",\n      \"evidence\": \"siRNA in C2C12, surface biotinylation, and in vivo knockdown/knockout mice with NMJ morphometry\",\n      \"pmids\": [\"21187406\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RER1 directly binds the \\u03b1-subunit TMD not shown\", \"Retrieval versus retention not distinguished\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Connected RER1 retention activity to \\u03b3-secretase trafficking and amyloidogenesis, defining a disease-relevant output of the receptor.\",\n      \"evidence\": \"Co-IP, reciprocal overexpression/knockdown, surface biotinylation, and A\\u03b2 ELISA\",\n      \"pmids\": [\"23043097\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which assembly intermediates RER1 acts on not resolved\", \"In vivo relevance not addressed in this study\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified the first regulator of RER1 abundance, showing an ER E3 ligase ubiquitinates RER1 and thereby tunes downstream \\u03b3-secretase assembly.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, Syvn knockout fibroblasts with nicastrin readouts\",\n      \"pmids\": [\"23129766\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Proteasomal versus lysosomal route not fully separated\", \"Signals triggering RER1 turnover unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showed RER1 cooperates with chaperone-based ER retention to trap disease-mutant membrane proteins, dissecting two parallel quality-control layers.\",\n      \"evidence\": \"Co-IP and single/double siRNA of Rer1 and calnexin with PMP22 mutants\",\n      \"pmids\": [\"25385046\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Therapeutic consequence of releasing trapped PMP22 not tested\", \"Direct TMD interaction not mapped\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Implicated RER1 in degradation of \\u03b1-synuclein and linked it to a second E3 ligase, broadening its role in proteostasis.\",\n      \"evidence\": \"Overexpression with C-terminal domain mutant, inhibitor studies, NEDD4 Co-IP, and Lewy body co-localization\",\n      \"pmids\": [\"28877262\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"NEDD4 interaction rests on a single pulldown\", \"Mechanistic placement of RER1 in degradation pathway partial\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established substrate-selective control of ion channel surface density in vivo, showing RER1 shapes neuronal excitability.\",\n      \"evidence\": \"Conditional and whole-brain Rer1 knockout mice with electrophysiology and channel-protein Westerns\",\n      \"pmids\": [\"28117367\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct RER1-Nav binding not demonstrated\", \"Basis of selectivity for Nav1.1/1.6 over other channels unexplained\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Placed RER1 in a developmental signaling cascade, demonstrating that its control of surface \\u03b3-secretase feeds Notch signaling and stem cell maintenance.\",\n      \"evidence\": \"Cortex-specific knockout mice with \\u03b3-secretase activity, Notch reporter, and lysosomal trafficking assays\",\n      \"pmids\": [\"30260951\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which \\u03b3-secretase components are diverted to lysosomes not fully resolved\", \"Direct versus indirect Notch effect not separated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined a second ubiquitin pathway controlling RER1 via a mapped STPY motif and validated a new cargo, linking RER1 turnover to receptor ER retention.\",\n      \"evidence\": \"Nedd4-2+/- mice, Co-IP, STPY mutagenesis, IP-MS interactome, and Endo-H assay for GABA-A \\u03b11\",\n      \"pmids\": [\"35832397\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of SYVN1 versus NEDD4-2 not compared\", \"Functional consequence of GABA-A \\u03b11 retention not measured\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified transcriptional regulation of RER1 by glucocorticoid signaling, connecting stress hormones to \\u03b3-secretase activity and mitochondrial amyloid pathology.\",\n      \"evidence\": \"ChIP of GR on RER1 promoter, gain/loss-of-function in cells and mice, MAM fractionation, and respiration/memory assays\",\n      \"pmids\": [\"37494768\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RER1 loss localizes PSEN1 maturation to MAM not mechanistically detailed\", \"GR co-regulators at the promoter unidentified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended RER1 quality control to innate immune receptor assembly, showing its retention of unassembled DAP12 is required for phagocytic function.\",\n      \"evidence\": \"Co-IP, endogenous CRISPR knockout in THP-1 cells, surface, signaling, and phagocytosis assays\",\n      \"pmids\": [\"39008111\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"TMD signal in DAP12 recognized by RER1 not mapped\", \"Whether TREM2 itself is a cargo not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Linked RER1 to organismal proteostasis and cell competition, positioning it as a Myc-induced cytoprotective factor against ER stress.\",\n      \"evidence\": \"Drosophila clonal analysis, p-eIF2\\u03b1 staining, and Rer1-Myc genetic epistasis in wing epithelium\",\n      \"pmids\": [\"38408084\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Link to proteostasis is indirect\", \"Specific cargoes underlying proteotoxic stress not identified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Proposed RER1 controls localization of a sterol-metabolizing enzyme relevant to hearing, expanding its cargo repertoire toward lipid homeostasis.\",\n      \"evidence\": \"Co-IP of HSD17B7 with RER1, mutant comparison, and cholesterol/localization assays in cells and zebrafish (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.07.15.665034\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP in a non-peer-reviewed preprint\", \"Direct interaction not independently confirmed\", \"Mechanism of cholesterol mislocalization unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RER1 structurally discriminates among diverse transmembrane retention signals and how cargo selection is regulated across cell types remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural model of RER1-cargo TMD recognition\", \"Rules governing substrate selectivity across tissues unknown\", \"Coordination between transcriptional and post-translational regulation of RER1 not integrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0038024\", \"supporting_discovery_ids\": [0, 2, 6]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 4, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [1, 2, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 2, 4]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [5, 10]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PSEN1\", \"PSENEN\", \"NCSTN\", \"SYVN1\", \"NEDD4L\", \"PMP22\", \"TYROBP\", \"NEDD4\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}