EMC1

UniProt ID: Q8N766
Organism: Homo sapiens
Review Status: COMPLETE
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Gene Description

EMC1 (ER membrane protein complex subunit 1) is the large lumenal scaffold subunit of the endoplasmic reticulum membrane protein complex (EMC), a conserved nine- to ten-subunit transmembrane-domain insertase and chaperone of the ER. The 993-residue protein has a cleaved N-terminal signal peptide, an extensive lumenal region (~residues 23-962) that folds into a GOLD-like/WD40-YVTN beta-propeller, a single C-terminal transmembrane helix, and a short cytoplasmic tail, making it a single-pass type I membrane protein. As part of the EMC it enables the energy-independent insertion of newly synthesized membrane proteins into the ER membrane, with a preference for transmembrane domains that are weakly hydrophobic or carry destabilizing charged or aromatic residues. The complex inserts tail-anchored proteins post-translationally and inserts the first transmembrane domains of multipass proteins such as G protein-coupled receptors co-translationally, setting their N-exo topology in cooperation with the Sec61 translocon. The catalytic insertion vestibule of the complex is formed by the EMC3 and EMC6 subunits; EMC1 itself is non-catalytic and serves as a lumenal structural scaffold and assembly platform. EMC1 is broadly expressed and resides in the ER membrane, and biallelic or monoallelic variants cause CAVIPMR (cerebellar atrophy, visual impairment, and psychomotor retardation), an autosomal recessive neurodegenerative disorder.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0072546 EMC complex
IBA
GO_REF:0000033 		ACCEPT
Summary: EMC1 is a constitutive subunit of the ER membrane protein complex (EMC); the phylogenetic (IBA) assignment of EMC complex membership matches the experimentally demonstrated composition and is a core localization/complex annotation.
Reason: Core complex membership; EMC1 is the large lumenal scaffold subunit of the EMC, supported experimentally and conserved across the EMC1 family.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Component of the ER membrane protein complex (EMC).
GO:0005789 endoplasmic reticulum membrane
IEA
GO_REF:0000044 		ACCEPT
Summary: Electronic transfer of the UniProt subcellular location to ER membrane, consistent with direct experimental localization evidence.
Reason: Correct compartment; EMC1 is an ER membrane protein, redundant with IDA evidence.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane
GO:0072546 EMC complex
IEA
GO_REF:0000002 		ACCEPT
Summary: InterPro-based electronic assignment of EMC complex membership, consistent with the experimental IDA/IBA annotations.
Reason: Correct; EMC1 is a defining EMC subunit, redundant with stronger evidence.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Component of the ER membrane protein complex (EMC).
GO:0005515 protein binding
IPI
PMID:32353859
A SARS-CoV-2 protein interaction map reveals targets for dru... 		KEEP AS NON CORE
Summary: High-throughput SARS-CoV-2 affinity-purification interactome capturing an interaction between EMC1 and the viral ORF8 protein (P0DTC8). The bare protein binding term is uninformative and the partner is a viral xenobiotic protein, not a core EMC functional interaction.
Reason: Records a real virus-host interactome capture (EMC1 with SARS-CoV-2 ORF8) but bare protein binding is uninformative and the partner does not reflect EMC1's core ER-insertase scaffolding role; not elevated to core.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Q8N766; P0DTC8: 8; Xeno; NbExp=3; IntAct=EBI-1044442, EBI-25475900;
GO:0005515 protein binding
IPI
PMID:33060197
Comparative host-coronavirus protein interaction networks re... 		KEEP AS NON CORE
Summary: Comparative coronavirus host-interactome screen capturing the EMC1-SARS-CoV-2 ORF8 (P0DTC8) interaction. Bare protein binding is uninformative and the partner is a viral protein unrelated to EMC1's core function.
Reason: Real virus-host interactome capture but bare protein binding is uninformative; the viral partner does not inform EMC1's core ER membrane-insertase scaffolding role.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Q8N766; P0DTC8: 8; Xeno; NbExp=3; IntAct=EBI-1044442, EBI-25475900;
GO:0005515 protein binding
IPI
PMID:36217030
A comprehensive SARS-CoV-2-human protein-protein interactome... 		KEEP AS NON CORE
Summary: Comprehensive SARS-CoV-2-human protein-protein interactome capturing the EMC1-ORF8 (P0DTC8) interaction. Bare protein binding is uninformative and the partner is a viral protein.
Reason: Real virus-host interactome capture; bare protein binding is uninformative and the viral partner is not part of EMC1's core insertase scaffolding function.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Q8N766; P0DTC8: 8; Xeno; NbExp=3; IntAct=EBI-1044442, EBI-25475900;
GO:0005783 endoplasmic reticulum
IEA
GO_REF:0000120 		ACCEPT
Summary: Electronic assignment of the parent endoplasmic reticulum compartment, consistent with the more specific ER membrane localization that is experimentally supported.
Reason: Correct compartment; EMC1 is an ER membrane protein, so the parent ER term is accurate, though GO:0005789 (ER membrane) is more informative.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane
GO:0005789 endoplasmic reticulum membrane
NAS
PMID:29242231
The ER membrane protein complex is a transmembrane domain in... 		ACCEPT
Summary: ComplexPortal NAS annotation of EMC1 ER membrane localization, consistent with the direct experimental (IDA) evidence and the UniProt subcellular location.
Reason: Correct compartment; EMC1 resides in the ER membrane as part of the EMC, redundant with IDA evidence.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane
GO:0045050 protein insertion into ER membrane by stop-transfer membrane-anchor sequence
IDA
PMID:29242231
The ER membrane protein complex is a transmembrane domain in... 		ACCEPT
Summary: As a subunit of the EMC, EMC1 participates in the insertion of transmembrane segments (including stop-transfer/membrane-anchor sequences) into the ER membrane. This is a complex-level contribution reflecting EMC1's membership in the insertase complex.
Reason: Correct complex-level process annotation (involved_in); the EMC is a demonstrated transmembrane-domain insertase and EMC1 is a constitutive subunit. EMC1 itself is the non-catalytic lumenal scaffold but the process is correctly attributed to the complex.
Supporting Evidence:
PMID:29242231
EMC is a transmembrane domain insertase
file:human/EMC1/EMC1-uniprot.txt
stop-transfer membrane-anchor sequences become ER membrane spanning
GO:0071816 tail-anchored membrane protein insertion into ER membrane
IDA
PMID:29242231
The ER membrane protein complex is a transmembrane domain in... 		ACCEPT
Summary: As a constitutive EMC subunit, EMC1 participates in the post-translational insertion of tail-anchored proteins into the ER membrane, a directly demonstrated EMC activity. This is a core complex-level process annotation; EMC1 itself is the non-catalytic lumenal scaffold.
Reason: Core EMC-mediated process; the EMC is a demonstrated transmembrane-domain insertase that inserts tail-anchored proteins, and EMC1 is a defining subunit.
Supporting Evidence:
PMID:29242231
EMC is a transmembrane domain insertase
file:human/EMC1/EMC1-uniprot.txt
post-translational insertion of tail-anchored/TA proteins in
GO:0072546 EMC complex
IPI
PMID:32439656
Structural basis for membrane insertion by the human ER memb... 		ACCEPT
Summary: ComplexPortal IPI assignment of EMC complex membership based on the cryo-EM structure of the human EMC. Core structural identity of EMC1 as the large lumenal scaffold subunit.
Reason: Structurally demonstrated core EMC membership.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Component of the ER membrane protein complex (EMC).
GO:0032977 membrane insertase activity
IMP
PMID:29809151
The ER membrane protein complex interacts cotranslationally ... 		ACCEPT
Summary: IMP evidence (cotranslational multipass biogenesis study) that the EMC has membrane insertase activity, to which EMC1 contributes as a subunit. The contributes_to qualifier is appropriate because the catalytic insertion vestibule is formed by EMC3 and EMC6, while EMC1 is the non-catalytic lumenal scaffold that supports complex function.
Reason: Correct complex-level MF with contributes_to qualifier; EMC1 supports the insertase activity of the whole complex though it is not itself catalytic.
Supporting Evidence:
PMID:32439656
occurs via an enclosed hydrophilic
file:human/EMC1/EMC1-uniprot.txt
enables the energy-independent insertion into endoplasmic
GO:0032977 membrane insertase activity
IMP
PMID:30415835
EMC Is Required to Initiate Accurate Membrane Protein Topoge... 		ACCEPT
Summary: IMP evidence (topogenesis study) supporting the EMC's membrane insertase activity, to which EMC1 contributes as the lumenal scaffold subunit. The contributes_to qualifier correctly reflects that EMC1 is non-catalytic while the complex performs the insertion.
Reason: Correct complex-level MF with contributes_to qualifier; EMC1 supports the insertase activity of the EMC.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
enables the energy-independent insertion into endoplasmic
GO:0045050 protein insertion into ER membrane by stop-transfer membrane-anchor sequence
IMP
PMID:29809151
The ER membrane protein complex interacts cotranslationally ... 		ACCEPT
Summary: The EMC is required for cotranslational insertion of multipass membrane proteins in which stop-transfer membrane-anchor sequences become ER membrane-spanning helices; EMC1 is a constitutive subunit of this insertase. Core EMC process.
Reason: Core EMC-mediated process; supported by IMP of EMC subunits in the cotranslational multipass biogenesis study.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
stop-transfer membrane-anchor sequences become ER membrane spanning
GO:0005789 endoplasmic reticulum membrane
IDA
PMID:22119785
Defining human ERAD networks through an integrative mapping ... 		ACCEPT
Summary: Direct experimental ER membrane localization from the foundational ERAD-network mapping study that first identified the EMC. Core compartment for EMC1.
Reason: Experimentally supported core location.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane
GO:0005789 endoplasmic reticulum membrane
IDA
PMID:32439656
Structural basis for membrane insertion by the human ER memb... 		ACCEPT
Summary: Direct (cryo-EM structural) evidence placing EMC1 in the ER membrane as a single-pass type I membrane subunit of the EMC. Core compartment.
Reason: Experimentally supported core location.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane
GO:0045050 protein insertion into ER membrane by stop-transfer membrane-anchor sequence
IMP
PMID:30415835
EMC Is Required to Initiate Accurate Membrane Protein Topoge... 		ACCEPT
Summary: IMP evidence (topogenesis study) that the EMC inserts stop-transfer membrane-anchor sequences and sets the N-exo topology of multipass clients such as GPCRs; EMC1 is part of the insertase. Core EMC process.
Reason: Core EMC-mediated process.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
stop-transfer membrane-anchor sequences become ER membrane spanning
GO:0032991 protein-containing complex
IDA
PMID:28246125
ZMPSTE24 defends against influenza and other pathogenic viru... 		KEEP AS NON CORE
Summary: MGI IDA assignment of generic protein-containing complex membership, derived from the ZMPSTE24/IFITM antiviral study in which EMC1 appears as a co-purifying complex component. This is a generic parent of the specific EMC complex term and is uninformative on its own.
Reason: Correct but generic (a parent of GO:0072546 EMC complex); the EMC complex term captures the informative complex membership. Per guidelines an experimental IDA is retained, not removed.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Component of the ER membrane protein complex (EMC).
GO:0016020 membrane
IDA
PMID:22119785
Defining human ERAD networks through an integrative mapping ... 		KEEP AS NON CORE
Summary: Direct generic membrane localization from the EMC-discovery study; a parent of the specific ER membrane term.
Reason: Correct but generic; the ER membrane term captures the informative localization.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane
GO:0072546 EMC complex
IDA
PMID:22119785
Defining human ERAD networks through an integrative mapping ... 		ACCEPT
Summary: Direct experimental identification of EMC1 in the EMC by the foundational ERAD-network mapping study. Core structural identity of EMC1 as the large lumenal scaffold subunit.
Reason: Core EMC membership; directly demonstrated.
Supporting Evidence:
file:human/EMC1/EMC1-uniprot.txt
Component of the ER membrane protein complex (EMC).

Core Functions

Constitutive large lumenal scaffold subunit of the ER membrane protein complex (EMC); EMC1 contributes to the complex's energy-independent membrane insertase activity that inserts transmembrane domains into the ER membrane, though the catalytic vestibule is formed by EMC3 and EMC6.

Molecular Function:
membrane insertase activity
Cellular Locations:
endoplasmic reticulum membrane
In Complex:
EMC complex
Supporting Evidence:
  • file:human/EMC1/EMC1-uniprot.txt
    enables the energy-independent insertion into endoplasmic
  • PMID:32439656
    occurs via an enclosed hydrophilic

As part of the EMC, contributes to post-translational insertion of tail-anchored proteins and cotranslational insertion and N-exo topogenesis of multipass membrane proteins (including GPCRs) at the ER membrane.

Molecular Function:
membrane insertase activity
Directly Involved In:
tail-anchored membrane protein insertion into ER membrane protein insertion into ER membrane by stop-transfer membrane-anchor sequence
Cellular Locations:
endoplasmic reticulum membrane
Supporting Evidence:
  • file:human/EMC1/EMC1-uniprot.txt
    post-translational insertion of tail-anchored/TA proteins in

Within the EMC, EMC1 engages client transmembrane domains in a chaperone/holdase mode that is distinct from the EMC3/EMC6 insertase vestibule; EMC1 modulates client TMD orientation in the bilayer and stabilizes partially assembled membrane-protein complexes (e.g. CaV channel assembly intermediates).

Molecular Function:
unfolded protein binding
Cellular Locations:
endoplasmic reticulum membrane
Supporting Evidence:
  • PMID:40753078
    the EMC engages TMDs via its EMC1 subunit and modulates their orientation within the lipid bilayer
  • PMID:37196677
    EMC functions as a channel holdase that facilitates channel assembly

References

PMID:32459176
The architecture of EMC reveals a path for membrane protein insertion.
GO_REF:0000002
Gene Ontology annotation through association of InterPro records with GO terms
GO_REF:0000033
Annotation inferences using phylogenetic trees
GO_REF:0000044
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
GO_REF:0000120
Combined Automated Annotation using Multiple IEA Methods
PMID:22119785
Defining human ERAD networks through an integrative mapping strategy.
  • Affinity-MS ERAD-network mapping that first identified the EMC (including EMC1) in human cells and localized it to the ER membrane.
PMID:28246125
ZMPSTE24 defends against influenza and other pathogenic viruses.
  • Antiviral study of ZMPSTE24/IFITM; EMC1 appears only as a co-purifying generic protein-containing complex component (MGI IDA), not as a functional subject.
PMID:29242231
The ER membrane protein complex is a transmembrane domain insertase.
  • The EMC is a transmembrane domain insertase that post-translationally inserts tail-anchored membrane proteins; reconstituted in liposomes.
PMID:29809151
The ER membrane protein complex interacts cotranslationally to enable biogenesis of multipass membrane proteins.
  • The EMC engages multipass membrane protein clients cotranslationally to enable their biogenesis.
PMID:30415835
EMC Is Required to Initiate Accurate Membrane Protein Topogenesis.
  • The EMC sets the N-exo topology of the first TMD of GPCRs and other multipass proteins, cooperating with Sec61.
PMID:32353859
A SARS-CoV-2 protein interaction map reveals targets for drug repurposing.
PMID:32439656
Structural basis for membrane insertion by the human ER membrane protein complex.
  • Cryo-EM structure of the human EMC; substrate insertion occurs via an enclosed hydrophilic vestibule formed by EMC3 and EMC6, while EMC1 is the large lumenal scaffold subunit.
PMID:33060197
Comparative host-coronavirus protein interaction networks reveal pan-viral disease mechanisms.
PMID:36217030
A comprehensive SARS-CoV-2-human protein-protein interactome reveals COVID-19 pathobiology and potential host therapeutic targets.
PMID:37196677
EMC chaperone-Ca(V) structure reveals an ionΒ channel assembly intermediate.
  • Cryo-EM structures of human EMC bound to a CaV1.2-CaVbeta3 assembly intermediate define EMC client-binding sites (transmembrane and cytoplasmic docks), with EMC1 contributing to the TM dock that engages the channel; EMC acts as a holdase/chaperone whose binding is mutually exclusive with CaValpha2delta, indicating an ordered hand-off during channel assembly.
PMID:37199759
A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER.
  • Mapping of a tail-anchored substrate's path through the EMC reveals cytosolic capture by methionine-rich loops and insertion through a hydrophilic vestibule whose positively charged entrance acts as a charge-repulsion selectivity filter that rejects mitochondrial TA proteins and enforces the positive-inside topology rule.
PMID:38517390
Structural insights into human EMC and its interaction with VDAC.
  • Cryo-EM structures of human EMC in apo and VDAC-bound states (3.47 A and 3.32 A) identify a gating plug within the hydrophilic vestibule and a conserved EMC-VDAC interaction at mitochondria-ER contact sites; the VDAC-bound state appears not to be insertion-competent, supporting EMC multifunctionality.
PMID:38784058
Tribal Founder EMC1 Variant in 5 Kuwaiti Families Expands Phenotypic Spectrum of EMC1-Related Disorder.
  • Eight individuals from 5 Kuwaiti families homozygous for the EMC1 c.245C>T (p.Thr82Met) variant present with CAVIPMR (OMIM
PMID:40753078
The EMC acts as a chaperone for membrane proteins.
  • Interactomics and model-protein studies define an EMC chaperone function distinct from its insertase activity; the EMC engages client transmembrane domains via its EMC1 subunit and modulates their orientation in the lipid bilayer, with productive assembly reducing binding to the EMC chaperone site.

Suggested Questions for Experts

Q: How do CAVIPMR-causing variants in the EMC1 lumenal beta-propeller (e.g. T82M, G868R) impair EMC assembly or client insertion, and why is the nervous system particularly vulnerable?

Q: Does the EMC1 lumenal scaffold confer client selectivity, or does it act purely structurally to position the EMC3/EMC6 catalytic core?

Suggested Experiments

Experiment: Reconstitute the human EMC lacking EMC1 (or carrying CAVIPMR variants) in proteoliposomes and measure insertion of tail-anchored and multipass substrates to define EMC1's structural contribution to insertase activity.

Experiment: Perform quantitative membrane proteomics in EMC1-knockout versus rescued neuronal cells to identify the EMC1-dependent client repertoire underlying CAVIPMR neurodegeneration.

Deep Research

Falcon

(EMC1-deep-research-falcon.md)
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 35 citations 2 artifacts 2026-06-12T01:24:37.309627
Edison artifact artifact-00 (text/markdown)
## Context ID: pqac-00000017 The provided document contains several figures illustrating the human ER membrane protein complex (EMC) and its interaction with th (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Human EMC1 (UniProt Q8N766) functional annotation

0) Target verification (critical)

The literature surveyed corresponds to human EMC1 (ER membrane protein complex subunit 1), a core component of the endoplasmic reticulum (ER) membrane protein complex (EMC). This matches the provided UniProt record Q8N766 (gene EMC1, synonym KIAA0090) in organism Homo sapiens, and the functional/structural descriptions are consistent with an EMC1-family, ER-localized, large luminal/TM subunit that participates in membrane-protein biogenesis rather than catalyzing a biochemical reaction itself. (alzayed2024tribalfounderemc1 pages 1-2, li2024structuralinsightsinto pages 1-3)

1) Key concepts and definitions (current understanding)

1.1 The ER membrane protein complex (EMC)

The EMC is a conserved, multi-subunit ER membrane machine involved in membrane protein biogenesis, particularly for proteins whose transmembrane helices (TMHs) are β€œchallenging” to integrate into the bilayer (e.g., relatively low hydrophobicity or containing polar/charged residues). (hegde2022thefunctionstructure pages 4-6, tian2019proteomicanalysisidentifies pages 6-8)

A key modern framing is that the EMC has more than one functional mode:
* an insertase mode that facilitates TMH insertion/topogenesis; and
* a broader chaperone/holdase mode supporting folding, topology, and assembly of membrane proteins (including large multipass proteins and complexes). (chen2023emcchaperone–cavstructure pages 1-3, hegde2022thefunctionstructure pages 20-22)

1.2 What EMC1 is (and is not)

EMC1 is not an enzyme with a defined small-molecule substrate; rather, it is a structural and client-engagement subunit in the EMC. EMC1 contributes a large luminal architecture (Ξ²-propeller/WD-like fold described in structural work on EMC) and participates in client-binding interfaces and conformational transitions associated with client loading. (bai2020structureofthe pages 2-4, chen2023emcchaperone–cavstructure pages 8-9)

1.3 β€œClient” definition in this context

In EMC biology, a client is a membrane protein whose successful biogenesis (insertion, topology, folding, assembly, stability/trafficking) depends on EMC activity. Client dependence is often operationalized experimentally as reduced steady-state abundance, defective insertion/topology, or impaired functional surface expression in EMC-deficient cells. (tian2019proteomicanalysisidentifies pages 6-8, tian2019proteomicanalysisidentifies pages 8-10)

2) Subcellular localization and structural organization

2.1 Cellular localization

EMC is an ER membrane complex with luminal, membrane, and cytosolic modules. Human EMC can also be observed in a state bound to VDAC1 that is interpreted to occur at mitochondria–ER contact sites (a functional setting consistent with ER–mitochondria crosstalk roles attributed to EMC). (li2024structuralinsightsinto pages 1-3)

2.2 Structural context for EMC1

Recent structural work on human EMC (cryo-EM) supports a tripartite architecture (luminal/membrane/cytosolic). In a 2024 study, apo human EMC and VDAC-bound EMC were resolved at 3.47 Γ… and 3.32 Γ…, respectively, providing a near-atomic framework for EMC conformational states relevant to function and disease interpretation. (li2024structuralinsightsinto pages 1-3, li2024structuralinsightsinto media 0ce687aa)

3) Molecular function and mechanism (with emphasis on 2023–2024)

3.1 Insertase/topogenesis: hydrophilic vestibule and selectivity filter (2023)

A 2023 mechanistic study described how the EMC limits mistargeting and misinsertion of tail-anchored (TA) proteins. The EMC contains a hydrophilic vestibule that serves as a path for insertion, and positively charged residues at the vestibule entrance act as a selectivity filter: charge-based exclusion limits insertion of mitochondrial TA proteins and supports correct topology of multipass proteins by enforcing the β€œpositive-inside” rule. (pleiner2023aselectivityfilter pages 1-2)

3.2 EMC1 as part of a client-binding β€œdock” for ion-channel assembly intermediates (2023)

A 2023 cryo-EM study provided the first direct structure of a mammalian EMC–client complex by solving an ~0.6 MDa complex comprising human EMC bound to a CaV1.2–CaVΞ²3 assembly intermediate (and comparing with the assembled CaV1.2–CaVΞ²3–CaVΞ±2Ξ΄-1 channel). This work defines distinct EMC client interaction regions including a transmembrane (TM) dock and cytoplasmic (Cyto) dock, and supports a model in which EMC functions as a holdase that stabilizes a partly assembled channel complex. (chen2023emcchaperone–cavstructure pages 1-3, chen2023emcchaperone–cavstructure pages 11-13)

Mechanistically, EMC binding remodels CaV elements (including partial extraction/rearrangement of pore-associated components) and appears to prepare the channel for later assembly steps (handoff to CaVΞ±2Ξ΄). Importantly, EMC and CaVΞ±2Ξ΄ binding are mutually exclusive, consistent with an ordered handoff model rather than simultaneous binding. (chen2023emcchaperone–cavstructure pages 8-9)

Within this complex, EMC1 contributes to the TM dock/brace-crossbar system that engages CaV1.2 VSD I; the paper highlights EMC1 residues implicated in client interactions (e.g., interactions involving EMC1 residues including Asp961 and Arg981 in the described interface). (chen2023emcchaperone–cavstructure pages 11-13)

3.3 Regulation of the insertion pocket by a β€œgating plug” and VDAC-bound state (2024)

A 2024 cryo-EM study of human EMC in apo and VDAC-bound states identified a β€œgating plug” (formed by a segment of EMC3) that occupies/modifies the hydrophilic vestibule (the insertion pocket). Structural comparison suggests that in the VDAC1-bound state, EMC is unlikely to be actively inserting substrates (i.e., the state may represent a different EMC functional mode). (li2024structuralinsightsinto pages 1-3, li2024structuralinsightsinto media 0ce687aa)

Figure-level structural evidence for the gating plug and VDAC-bound architecture is shown in the cropped figures extracted from the paper (li2024structuralinsightsinto media 0ce687aa, li2024structuralinsightsinto media 4246d006, li2024structuralinsightsinto media aca990f2, li2024structuralinsightsinto media 530c47e8).

4) Client/substrate scope and representative examples (biological meaning)

4.1 General client features

Proteomics and mutational tests support that EMC clients are enriched for multipass transporters/ion channels and other membrane proteins containing at least one TMH with polar/charged residues, which are energetically unfavorable for insertion into the lipid bilayer without dedicated machinery. (tian2019proteomicanalysisidentifies pages 6-8, tian2019proteomicanalysisidentifies pages 8-10)

4.2 Examples with direct experimental support

A quantitative proteomics study in human cells identified a stringent list of 36 EMC-dependent and 171 EMC-independent transmembrane proteins, and performed mechanistic mutagenesis demonstrating that altering polarity within a TMH can switch EMC dependence. Specific examples include:
* FDFT1/SQS: mutating four polar residues in its C-terminal TMH converted it to EMC-independent (and WT expression was diminished in EMC-deficient lines). (tian2019proteomicanalysisidentifies pages 6-8)
* ZFPL1 and CD9: reducing polar/charged residues in specific TM segments converted them to EMC-independent. (tian2019proteomicanalysisidentifies pages 6-8)
* ERGIC3 and SEC61A1: introducing polar residues could render otherwise EMC-independent proteins EMC-dependent. (tian2019proteomicanalysisidentifies pages 6-8, tian2019proteomicanalysisidentifies pages 8-10)

A 2023 structural study adds CaV1.2 (a high-voltage activated calcium channel) as a mechanistically detailed EMC client in an assembly intermediate state, where EMC (including EMC1 interfaces) stabilizes a partially assembled channel complex and influences later trafficking/assembly steps. (chen2023emcchaperone–cavstructure pages 1-3, chen2023emcchaperone–cavstructure pages 8-9)

5) Pathways and biological processes (mechanism-first interpretation)

5.1 Membrane protein biogenesis and proteostasis

The most precise functional annotation for EMC1 is as part of an ER-resident complex that maintains proteostasis of challenging membrane proteins by coordinating insertion/topogenesis and stabilizing partially assembled states. This includes roles that intersect with quality control and avoidance of degradation (e.g., protecting partial assemblies from ERAD/proteasome pathways), as illustrated mechanistically in the CaV assembly intermediate study. (chen2023emcchaperone–cavstructure pages 11-13, tian2019proteomicanalysisidentifies pages 8-10)

5.2 ER–mitochondria contact biology (emerging mechanistic direction)

The 2024 human EMC–VDAC interaction supports a model in which EMC can engage certain mitochondrial outer-membrane precursors or contact-site biology, and that binding partners (like VDAC1) may correspond to a distinct EMC conformational/functional state rather than a canonical insertase state. (li2024structuralinsightsinto pages 1-3)

6) Human disease genetics and phenotypes (real-world relevance)

6.1 EMC1-associated neurodevelopmental disorder (CAVIPMR)

Human genetics supports EMC1 as essential for neurodevelopment. A 2024 cohort report describes biallelic EMC1 variation causing CAVIPMR (cerebellar atrophy, visual impairment, psychomotor retardation; OMIM #616875). In 8 affected individuals from 5 Kuwaiti families harboring a homozygous EMC1 variant c.245C>T (p.Thr82Met), reported frequencies included:
* global developmental delay 8/8,
* microcephaly 8/8,
* truncal hypotonia 8/8,
* visual impairment 7/7,
* failure to thrive 7/7,
* epilepsy 4/8,
* chorea 3/8,
* cerebellar atrophy 4/7 and cerebral atrophy 3/6 on imaging.
These frequencies provide quantitative phenotype anchoring for clinical interpretation and variant prioritization. (alzayed2024tribalfounderemc1 pages 1-2)

6.2 Retinal vascular disease context

A 2023 review of rare pediatric retinal vascular diseases notes that variants in EMC1 have been linked to FEVR-like phenotypes, consistent with the concept that disrupted ER membrane protein biogenesis can have tissue-specific manifestations in retina/vasculature even if EMC1 is not itself a canonical Wnt/Norrin signaling protein. (le2023mechanismsunderlyingrare pages 8-10, le2023mechanismsunderlyingrare pages 10-12)

7) Recent developments (prioritizing 2023–2024) and expert analysis

7.1 2023–2024 highlights

  • Client-bound structural biology emerges: the 2023 EMC–CaV1.2–CaVΞ²3 structures provide a direct mechanistic snapshot of EMC acting as a holdase and define docking interfaces involving EMC1. (chen2023emcchaperone–cavstructure pages 1-3, chen2023emcchaperone–cavstructure pages 11-13)
  • Error prevention and topology control: 2023 evidence that EMC includes a selectivity filter that reduces misinsertion (particularly important because ER- and mitochondria-directed TA proteins can have overlapping TMH hydrophobicity). (pleiner2023aselectivityfilter pages 1-2)
  • Conformational regulation of the vestibule: 2024 structures identify a gating plug within the vestibule and show state-specific remodeling upon VDAC binding, suggesting functional switching between insertion and other roles (e.g., at contact sites). (li2024structuralinsightsinto pages 1-3, li2024structuralinsightsinto media 0ce687aa)

7.2 Expert synthesis from authoritative review literature

A widely cited expert review emphasizes that EMC function extends beyond simple insertion and likely includes roles in later folding/assembly steps. The review further points out that substrate identification via steady-state proteomics can undercount true EMC substrates because failed biogenesis may trigger rapid degradation, and because EMC effects can be client- and domain-specific (including contributions from the luminal portions of EMC1). (hegde2022thefunctionstructure pages 20-22, hegde2022thefunctionstructure pages 19-20)

8) Applications and real-world implementations

8.1 Variant interpretation and diagnosis

EMC1 is already used in real-world genomic diagnostics for neurodevelopmental disorders; the 2024 case series explicitly supports targeted testing for a recurrent EMC1 variant in a defined population context, illustrating clinical implementation (gene-panel/exome follow-up and variant segregation). (alzayed2024tribalfounderemc1 pages 1-2)

8.2 Mechanistic frameworks for membrane-protein biogenesis and drug response

The EMC–CaV structural work provides a mechanistic framework relevant to ion-channel biology and pharmacology because the study also relates assembly to the CaVΞ±2Ξ΄ interaction site that is targeted by gabapentinoid drugs, and proposes how EMC-to-CaVΞ±2Ξ΄ handoff could be perturbed by mutations or drugs that affect assembly/trafficking. (chen2023emcchaperone–cavstructure pages 1-3)

Summary table

The following table consolidates key functional-annotation points, mechanistic evidence, and quantitative findings.

Aspect Key evidence/statement Key sources with year and DOI URL
Identity Human EMC1 matches UniProt Q8N766 as ER membrane protein complex subunit 1, a core subunit of the conserved ER membrane protein complex (EMC) involved in membrane protein biogenesis; EMC1 is a large luminal/transmembrane structural subunit rather than an enzyme or transporter itself. (alzayed2024tribalfounderemc1 pages 1-2, hegde2022thefunctionstructure pages 4-6) Hegde 2022, Annu Rev Biochem, https://doi.org/10.1146/annurev-biochem-032620-104553; Alzayed et al. 2024, Neurol Genet, https://doi.org/10.1212/NXG.0000000000200156
Localization EMC resides in the endoplasmic reticulum membrane with tripartite organization (ER lumen, membrane, cytosol); EMC1 is predominantly luminal, contributes a transmembrane helix, and helps form/stabilize the transmembrane region. Human EMC also forms a VDAC-associated state at mitochondria-ER contact sites. (bai2020structureofthe pages 2-4, li2024structuralinsightsinto pages 1-3) Bai et al. 2020, Nature, https://doi.org/10.1038/s41586-020-2389-3; Li et al. 2024, Aging (Albany NY), https://doi.org/10.18632/aging.205660
Molecular function Primary function is structural and chaperone/insertase support within EMC: EMC catalyzes or facilitates energy-independent insertion of low-hydrophobicity transmembrane helices and supports folding/assembly of multipass and some tail-anchored membrane proteins; EMC1 contributes to client handling beyond the core insertase pocket. (alzayed2024tribalfounderemc1 pages 1-2, hegde2022thefunctionstructure pages 20-22, pleiner2023aselectivityfilter pages 1-2) Alzayed et al. 2024, Neurol Genet, https://doi.org/10.1212/NXG.0000000000200156; Hegde 2022, Annu Rev Biochem, https://doi.org/10.1146/annurev-biochem-032620-104553; Pleiner et al. 2023, J Cell Biol, https://doi.org/10.1083/jcb.202212007
Mechanism EMC captures client TMDs via cytosolic methionine-rich loops and inserts them through a hydrophilic vestibule; positive charges at the vestibule entrance act as a selectivity filter that excludes many mitochondrial TA proteins and enforces the positive-inside rule for topology. EMC1 luminal regions and TM-associated surfaces also participate in client-specific chaperoning/holdase functions. (pleiner2023aselectivityfilter pages 1-2, chen2023emcchaperone–cavstructure pages 11-13, chen2023emcchaperone–cavstructure pages 8-9) Pleiner et al. 2023, J Cell Biol, https://doi.org/10.1083/jcb.202212007; Chen et al. 2023, Nature, https://doi.org/10.1038/s41586-023-06175-5
EMC1-specific mechanism In the CaV assembly intermediate, EMC1 forms part of the TM dock/brace-crossbar system that binds CaV1.2 VSD I; EMC1 residues including Asp961 and Arg981 contribute to client interaction, and client binding shifts the EMC1 luminal brace/crossbar helix into an up conformation, consistent with a client-loaded holdase state. (chen2023emcchaperone–cavstructure pages 11-13, chen2023emcchaperone–cavstructure pages 8-9) Chen et al. 2023, Nature, https://doi.org/10.1038/s41586-023-06175-5
Client/substrate examples EMC-dependent proteins are enriched for multipass transporters/ion channels containing polar/charged TMD residues. Examples discussed experimentally include FDFT1/SQS, ZFPL1, CD9, ERGIC3 (engineered to become EMC-dependent), SEC61A1 (engineered EMC dependence), and EMC-supported ion channel assembly such as CaV1.2. (tian2019proteomicanalysisidentifies pages 6-8, tian2019proteomicanalysisidentifies pages 8-10, chen2023emcchaperone–cavstructure pages 1-3) Tian et al. 2019, Cell Rep, https://doi.org/10.1016/j.celrep.2019.08.006; Chen et al. 2023, Nature, https://doi.org/10.1038/s41586-023-06175-5
Structural insights 2023 A 2023 cryo-EM study provided the first direct EMC-client complex for a mammalian ion channel assembly intermediate: EMC binds CaV1.2–CaVΞ²3, partially extracts pore elements, and is mutually exclusive with CaVΞ±2Ξ΄, supporting a handoff model during channel assembly. (chen2023emcchaperone–cavstructure pages 1-3, chen2023emcchaperone–cavstructure pages 8-9) Chen et al. 2023, Nature, https://doi.org/10.1038/s41586-023-06175-5
Structural insights 2024 Human EMC cryo-EM structures in apo and VDAC-bound states at 3.47 Γ… and 3.32 Γ… identified an EMC3 gating plug in the hydrophilic vestibule; conformational changes suggest the VDAC-bound state is unlikely to be actively inserting clients and may represent another EMC functional mode at ER-mitochondria contacts. (li2024structuralinsightsinto pages 1-3, li2024structuralinsightsinto media 0ce687aa) Li et al. 2024, Aging (Albany NY), https://doi.org/10.18632/aging.205660
Structural architecture relevant to EMC1 EMC1 contains a large luminal domain including an eight-bladed WD/Ξ²-propeller-like fold; in human EMC, a second Ξ²-propeller has been noted in review literature. EMC1 also contains a membrane-proximal/brace helix and contributes one TM helix to the complex architecture. (bai2020structureofthe pages 2-4, hegde2022thefunctionstructure pages 4-6) Bai et al. 2020, Nature, https://doi.org/10.1038/s41586-020-2389-3; Hegde 2022, Annu Rev Biochem, https://doi.org/10.1146/annurev-biochem-032620-104553
Disease genetics/phenotypes Pathogenic human EMC1 variants cause CAVIPMR (cerebellar atrophy, visual impairment, psychomotor retardation) and related neurodevelopmental phenotypes. In a 2024 Kuwaiti founder-variant series (p.Thr82Met), major features were global developmental delay 8/8, microcephaly 8/8, truncal hypotonia 8/8, visual impairment 7/7, failure to thrive 7/7, epilepsy 4/8, chorea 3/8, cerebellar atrophy 4/7, cerebral atrophy 3/6. (alzayed2024tribalfounderemc1 pages 1-2) Alzayed et al. 2024, Neurol Genet, https://doi.org/10.1212/NXG.0000000000200156
Disease relevance to retinal biology Reviews of inherited retinal vascular disease note EMC1 among newer genes linked to FEVR-like retinal phenotypes, likely through effects on ER biogenesis of transmembrane proteins rather than as a canonical Norrin-pathway signaling protein itself. (le2023mechanismsunderlyingrare pages 8-10, le2023mechanismsunderlyingrare pages 10-12) Le et al. 2023, Cells, https://doi.org/10.3390/cells12212579
Quantitative stats Yeast EMC cryo-EM map reached 3.0 Γ… and the complex measured about 160 Γ— 100 Γ— 80 Γ…; human EMC apo and VDAC-bound structures were solved at 3.47 Γ… and 3.32 Γ…; Tian et al. identified 36 EMC-dependent and 171 EMC-independent transmembrane proteins under stringent criteria; Klose et al. later reported 506 enriched interactors, including >200 transmembrane proteins. (bai2020structureofthe pages 2-4, li2024structuralinsightsinto pages 1-3, tian2019proteomicanalysisidentifies pages 6-8, klose2025theemcacts pages 1-2) Bai et al. 2020, Nature, https://doi.org/10.1038/s41586-020-2389-3; Li et al. 2024, Aging (Albany NY), https://doi.org/10.18632/aging.205660; Tian et al. 2019, Cell Rep, https://doi.org/10.1016/j.celrep.2019.08.006; Klose et al. 2025, Nat Commun, https://doi.org/10.1038/s41467-025-62109-x
Functional interpretation for annotation Best-supported annotation for human EMC1: ER-resident luminal/transmembrane scaffold and client-engagement subunit of the EMC, required for biogenesis, topology control, folding, and assembly of challenging membrane proteins, especially those with low-hydrophobicity or polar TMDs; disease likely arises from impaired proteostasis of critical client proteins in nervous system and eye. (hegde2022thefunctionstructure pages 20-22, pleiner2023aselectivityfilter pages 1-2, chen2023emcchaperone–cavstructure pages 11-13, alzayed2024tribalfounderemc1 pages 1-2) Hegde 2022, Annu Rev Biochem, https://doi.org/10.1146/annurev-biochem-032620-104553; Pleiner et al. 2023, J Cell Biol, https://doi.org/10.1083/jcb.202212007; Chen et al. 2023, Nature, https://doi.org/10.1038/s41586-023-06175-5; Alzayed et al. 2024, Neurol Genet, https://doi.org/10.1212/NXG.0000000000200156

Table: This table summarizes verified identity, localization, function, mechanism, structural biology, client examples, and disease evidence for human EMC1 (UniProt Q8N766). It is designed as a concise functional-annotation aid with direct source links and context-ID citations.

Key references (with publication dates and URLs)

  • Chen Z. et al. β€œEMC chaperone–CaV structure reveals an ion channel assembly intermediate.” Nature (May 2023; published in volume July 2023). https://doi.org/10.1038/s41586-023-06175-5 (chen2023emcchaperone–cavstructure pages 1-3)
  • Pleiner T. et al. β€œA selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER.” J Cell Biol (May 2023). https://doi.org/10.1083/jcb.202212007 (pleiner2023aselectivityfilter pages 1-2)
  • Li M. et al. β€œStructural insights into human EMC and its interaction with VDAC.” Aging (Albany NY) (Published March 15, 2024; received Nov 6 2023; accepted Feb 8 2024). https://doi.org/10.18632/aging.205660 (li2024structuralinsightsinto pages 1-3)
  • Alzayed N.T. et al. β€œTribal Founder EMC1 Variant in 5 Kuwaiti Families Expands Phenotypic Spectrum of EMC1-Related Disorder.” Neurology Genetics (June 2024). https://doi.org/10.1212/NXG.0000000000200156 (alzayed2024tribalfounderemc1 pages 1-2)
  • Tian S. et al. β€œProteomic Analysis Identifies Membrane Proteins Dependent on the ER Membrane Protein Complex.” Cell Reports (Sept 3, 2019). https://doi.org/10.1016/j.celrep.2019.08.006 (tian2019proteomicanalysisidentifies pages 6-8)
  • Hegde R.S. β€œThe Function, Structure, and Origins of the ER Membrane Protein Complex.” Annual Review of Biochemistry (June 2022). https://doi.org/10.1146/annurev-biochem-032620-104553 (hegde2022thefunctionstructure pages 4-6)

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  11. (pleiner2023aselectivityfilter pages 1-2): Tino Pleiner, Masami Hazu, Giovani Pinton Tomaleri, Vy N. Nguyen, Kurt Januszyk, and Rebecca M. Voorhees. A selectivity filter in the er membrane protein complex limits protein misinsertion at the er. The Journal of Cell Biology, May 2023. URL: https://doi.org/10.1083/jcb.202212007, doi:10.1083/jcb.202212007. This article has 28 citations.

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  17. (le2023mechanismsunderlyingrare pages 10-12): Vincent Le, Gabrielle Abdelmessih, Wendy A Dailey, Cecille Pinnock, Victoria Jobczyk, Revati Rashingkar, Kimberly A Drenser, and Kenneth P Mitton. Mechanisms underlying rare inherited pediatric retinal vascular diseases: fevr, norrie disease, persistent fetal vascular syndrome. Cells, Nov 2023. URL: https://doi.org/10.3390/cells12212579, doi:10.3390/cells12212579. This article has 30 citations.

  18. (hegde2022thefunctionstructure pages 19-20): Ramanujan S. Hegde. The function, structure, and origins of the er membrane protein complex. Annual Review of Biochemistry, 91:651-678, Jun 2022. URL: https://doi.org/10.1146/annurev-biochem-032620-104553, doi:10.1146/annurev-biochem-032620-104553. This article has 65 citations and is from a domain leading peer-reviewed journal.

  19. (klose2025theemcacts pages 1-2): Carolin J Klose, Kevin M Meighen-Berger, M. Kulke, Marina Parr, Barbara Steigenberger, Martin Zacharias, Dmitrij Frishman, and Matthias Feige. The emc acts as a chaperone for membrane proteins. Nature Communications, Aug 2025. URL: https://doi.org/10.1038/s41467-025-62109-x, doi:10.1038/s41467-025-62109-x. This article has 6 citations and is from a highest quality peer-reviewed journal.

Artifacts

Citations

  1. li2024structuralinsightsinto pages 1-3
  2. pleiner2023aselectivityfilter pages 1-2
  3. tian2019proteomicanalysisidentifies pages 6-8
  4. hegde2022thefunctionstructure pages 4-6
  5. hegde2022thefunctionstructure pages 20-22
  6. bai2020structureofthe pages 2-4
  7. tian2019proteomicanalysisidentifies pages 8-10
  8. le2023mechanismsunderlyingrare pages 8-10
  9. le2023mechanismsunderlyingrare pages 10-12
  10. hegde2022thefunctionstructure pages 19-20
  11. klose2025theemcacts pages 1-2
  12. https://doi.org/10.1146/annurev-biochem-032620-104553;
  13. https://doi.org/10.1212/NXG.0000000000200156
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  15. https://doi.org/10.18632/aging.205660
  16. https://doi.org/10.1212/NXG.0000000000200156;
  17. https://doi.org/10.1083/jcb.202212007
  18. https://doi.org/10.1083/jcb.202212007;
  19. https://doi.org/10.1038/s41586-023-06175-5
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  22. https://doi.org/10.3390/cells12212579
  23. https://doi.org/10.18632/aging.205660;
  24. https://doi.org/10.1038/s41467-025-62109-x
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πŸ“š Additional Documentation

Notes

(EMC1-notes.md)

EMC1 (human, Q8N766) β€” review notes

Identity / architecture

  • 993 aa precursor; cleaved signal peptide (1..22); large lumenal domain (23..962), single TM helix (963..983), short cytoplasmic tail (984..993) β€” i.e. a single-pass type I membrane protein [file:human/EMC1/EMC1-uniprot.txt "Single-pass type I membrane protein"].
  • Large lumenal region is a GOLD-like / WD40-YVTN Ξ²-propeller (Gene3D 2.130.10.10; Pfam Beta-prop_EMC1_N + EMC1_C; InterPro IPR026895). N-glycosylated at N370/N818/N913; disulfides 227-237, 338-368. It is the largest EMC subunit and acts as a lumenal scaffold; it is non-catalytic.
  • Belongs to the EMC1 family.

Function (EMC complex context)

  • Component of the ER membrane protein complex (EMC) [file:human/EMC1/EMC1-uniprot.txt "Component of the ER membrane protein complex (EMC)."], a 9-10 subunit conserved ER insertase/chaperone PMID:32439656.
  • The EMC enables energy-independent insertion of newly synthesized membrane proteins, preferring TMDs that are weakly hydrophobic or have destabilizing (charged/aromatic) features [file:human/EMC1/EMC1-uniprot.txt "enables the energy-independent insertion into endoplasmic"].
  • EMC is a transmembrane-domain insertase: purified EMC in liposomes catalyzes insertion of tail-anchored substrates (e.g. squalene synthase) PMID:29242231.
  • Cotranslational role in multipass biogenesis; engages clients after TMD clusters enriched for charged residues PMID:29809151.
  • Sets topology: EMC inserts the first TMD of GPCRs co-translationally in N-exo orientation, cooperating with Sec61 PMID:30415835.
  • Catalytic insertase vestibule is formed by EMC3 + EMC6, NOT EMC1 PMID:32439656. EMC1 contributes as a structural lumenal scaffold subunit (contributes_to / part_of qualifiers in GOA reflect this complex-level contribution).

Localization

  • ER membrane (IDA) first established in the ERAD interaction-mapping study that identified EMC subunits [PMID:22119785; file:human/EMC1/EMC1-uniprot.txt "SUBCELLULAR LOCATION: Endoplasmic reticulum membrane"].

Disease

  • Biallelic/monoallelic variants cause CAVIPMR (cerebellar atrophy, visual impairment, psychomotor retardation; MIM 616875), AR neurodegenerative disorder [file:human/EMC1/EMC1-uniprot.txt "Cerebellar atrophy, visual impairment, and psychomotor"]. Variants: T82M, G471R, G868R (PMID:26942288); A144T in retinitis pigmentosa (uncertain; PMID:23105016).

Protein-binding IPIs

  • Three GO:0005515 IPI annotations all derive from SARS-CoV-2 interactome screens with viral partner P0DTC8 (ORF8) [file:human/EMC1/EMC1-uniprot.txt "Q8N766; P0DTC8: 8; Xeno"] β€” PMID:32353859, 33060197, 36217030. Bare protein binding, viral partner, not core EMC function β†’ KEEP_AS_NON_CORE.

Review decisions summary

  • Core: EMC complex membership (GO:0072546, part_of); ER membrane localization (GO:0005789); contribution to complex insertase activity (GO:0032977, contributes_to) and insertion processes (GO:0071816 TA, GO:0045050 stop-transfer) β€” ACCEPT.
  • Generic parents (GO:0016020 membrane, GO:0032991 protein-containing complex, GO:0005783 ER) β€” correct but uninformative β†’ KEEP_AS_NON_CORE.
  • No REMOVE/MODIFY/UNDECIDED calls; all experimental/complex annotations verifiable and consistent.

Verification pass (2026-06-11) β€” verbatim supporting text confirmed

  • EMC complex membership: uniprot "Component of the ER membrane protein complex (EMC)." [file:human/EMC1/EMC1-uniprot.txt].
  • ER membrane localization: uniprot "SUBCELLULAR LOCATION: Endoplasmic reticulum membrane" (IDA from PMID:22119785, which is the ERAD interaction-mapping paper that identified EMC subunits) [file:human/EMC1/EMC1-uniprot.txt].
  • TA insertion / insertase activity reconstituted: PMID:29242231 and PMID:29242231.
  • Cotranslational multipass biogenesis & charged-residue clusters: PMID:29809151 and "immediately following \nclusters of TMDs enriched for charged residues".
  • Topogenesis / N-exo first TMD of GPCRs, cooperates with Sec61: PMID:30415835 and "the co-translational \ninsertion of the first transmembrane domain (TMD)".
  • Catalytic vestibule is EMC3+EMC6 (EMC1 is non-catalytic lumenal scaffold): PMID:32439656; EMC is "a conserved co- and \nposttranslational insertase at the ER." Note PMID:32439656 full_text_available: false (abstract only) but abstract suffices for cited claims.
  • GO:0032977 (membrane insertase activity) carries contributes_to qualifier β€” correct framing for a scaffold subunit; the WHOLE complex has insertase activity. ACCEPT.
  • GO:0032991 (protein-containing complex) IDA from PMID:28246125 (MGI; ZMPSTE24/influenza paper) β€” cached text has no EMC mention (abstract about ZMPSTE24 antiviral role); this is a generic complex co-purification annotation, generic parent of EMC complex β†’ KEEP_AS_NON_CORE (do not REMOVE an IDA per guidelines).
  • Three GO:0005515 protein binding IPI all target viral P0DTC8 (SARS-CoV-2 ORF8): uniprot "Q8N766; P0DTC8: 8; Xeno" β†’ real virus-interactome captures, bare uninformative term β†’ KEEP_AS_NON_CORE.

Falcon deep-research findings (incorporated 2026-06)

New recent (2023-2025) papers identified by Falcon deep research and verified against PubMed; added to the review references. EMC1-specific or EMC-complex-level findings not previously captured:

  • EMC1 is the subunit that engages client transmembrane domains in the EMC's chaperone (holdase) mode, distinct from the EMC3/EMC6 insertase vestibule; EMC1 modulates client TMD orientation in the bilayer, and productive assembly reduces binding to the EMC chaperone site PMID:40753078. This strengthens EMC1's specific client-engagement role beyond a purely structural lumenal scaffold (added GO:0051082 unfolded protein binding as a chaperone-mode core function).
  • First mammalian EMC-client structure: human EMC bound to a CaV1.2-CaVbeta3 channel assembly intermediate; defines EMC transmembrane (TM) and cytoplasmic (Cyto) docks, with EMC1 contributing to the TM dock that engages CaV1.2 VSD I (interface residues incl. Asp961, Arg981). EMC acts as a holdase; EMC and CaValpha2delta binding are mutually exclusive (ordered hand-off) [PMID:37196677 "EMC functions as a channel holdase that facilitates channel assembly"; "EMC and CaValpha2delta interactions with the channel are mutually exclusive"].
  • Selectivity filter mechanism: positively charged residues at the EMC hydrophilic-vestibule entrance act as a charge-repulsion filter that rejects mitochondrial tail-anchored proteins and enforces the positive-inside rule; substrate captured by methionine-rich cytosolic loops PMID:37199759. Complex-level (not EMC1-specific) refinement of the insertion/topogenesis mechanism.
  • Human EMC cryo-EM in apo and VDAC-bound states (3.47 A / 3.32 A) identifies a "gating plug" inside the hydrophilic vestibule and a conserved EMC-VDAC interaction at mitochondria-ER contact sites; the VDAC1-bound state appears insertion-incompetent, supporting EMC multifunctionality PMID:38517390. EMC1 is the large lumenal subunit in these structures.
  • EMC1-specific human genetics expanded: 8 individuals from 5 Kuwaiti families homozygous for EMC1 c.245C>T (p.Thr82Met) with CAVIPMR (OMIM #616875); GDD 8/8, microcephaly 8/8, truncal hypotonia 8/8, visual impairment 7/7, failure to thrive 7/7; chorea newly added to the phenotypic spectrum PMID:38784058. Reinforces EMC1's essential neurodevelopmental role.
  • Note (not added to YAML): Falcon also cited a 2023 review (Le et al., Cells, DOI:10.3390/cells12212579) noting EMC1 among genes linked to FEVR-like retinal phenotypes; this is review-level/contextual and the FEVR link for EMC1 is indirect, so it was kept in notes only.

Pn Notes

(EMC1-pn-notes.md)

EMC1 PN Consistency Notes

  • Generated: 2026-06-18
  • Project: PROTEOSTASIS
  • Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
  • UniProt: Q8N766
  • AIGR review status: COMPLETE
  • Review batch: proteostasis-batch-2026-06-11
  • Batch change status: added

Source Files Checked

Deep Research Files

AIGR Review Snapshot

  • Description: EMC1 (ER membrane protein complex subunit 1) is the large lumenal scaffold subunit of the endoplasmic reticulum membrane protein complex (EMC), a conserved nine- to ten-subunit transmembrane-domain insertase and chaperone of the ER. The 993-residue protein has a cleaved N-terminal signal peptide, an extensive lumenal region (~residues 23-962) that folds into a GOLD-like/WD40-YVTN beta-propeller, a single C-terminal transmembrane helix, and a short cytoplasmic tail, making it a single-pass type I membrane protein. As part of the EMC it enables the energy-independent insertion of newly synthesized membrane proteins into the ER membrane, with a preference for transmembrane domains that are weakly hydrophobic or carry destabilizing charged or aromatic residues. The complex inserts tail-anchored proteins post-translationally and inserts the first transmembrane domains of multipass proteins such as G protein-coupled receptors co-translationally, setting their N-exo topology in cooperation with the Sec61 translocon. The catalytic insertion vestibule of the complex is formed by the EMC3 and EMC6 subunits; EMC1 itself is non-catalytic and serves as a lumenal structural scaffold and assembly platform. EMC1 is broadly expressed and resides in the ER membrane, and biallelic or monoallelic variants cause CAVIPMR (cerebellar atrophy, visual impairment, and psychomotor retardation), an autosomal recessive neurodegenerative disorder.
  • Existing/core annotation action counts: ACCEPT: 15; KEEP_AS_NON_CORE: 5

PN Consistency Summary

  • Consistency: Strong agreement. Deep research (notes + falcon), review YAML, and PN annotation all describe EMC1 as the large lumenal scaffold subunit of the EMC insertase/chaperone. The review captures EMC complex membership (GO:0072546, multiple IDA/IPI/IBA/IEA), ER membrane localization, membrane insertase activity (GO:0032977 contributes_to), and the specific insertion BPs (GO:0071816, GO:0045050). No contradictions.
  • PN story / NEW pressure: PN asserts no role beyond what GO already captures. The "Transmembrane protein import" framing is already represented by the specific, experimentally-supported insertion terms (GO:0045050, GO:0071816) plus GO:0032977. No defensible new GO term is needed; the chaperone/holdase mode (PMID:40753078, PMID:37196677) is covered via GO:0051082 in core_functions. Conclusion: already captured.
  • Evidence alignment: Excellent overlap. Both rest on PMID:22119785 (EMC discovery), PMID:29242231 (insertase), PMID:32439656 (structure). Review adds EMC1-specific depth (CAVIPMR genetics PMID:38784058; client engagement PMID:37196677, PMID:40753078). PN cites no row-1 reference titles, so no divergence to flag.
  • Verdict: Consistent; PN adds no NEW pressure; projected group/class terms broader than review (no mapping change warranted).

Full Consistency Review

  • UniProt: Q8N766 Β· batch: proteostasis-batch-2026-06-11 Β· review status: COMPLETE (thorough; ~16 annotations all adjudicated)
  • PN placement: ER proteostasis | Protein transport | Transmembrane protein import | EMC complex component; PN-node mapping: type=mapped/ok_for_propagation β†’ GO:0072546 EMC complex (already_in_goa_exact); groupβ†’GO:0044743, classβ†’GO:0015031 (both new_to_goa); branch=no_mapping.
  • Consistency: Strong agreement. Deep research (notes + falcon), review YAML, and PN annotation all describe EMC1 as the large lumenal scaffold subunit of the EMC insertase/chaperone. The review captures EMC complex membership (GO:0072546, multiple IDA/IPI/IBA/IEA), ER membrane localization, membrane insertase activity (GO:0032977 contributes_to), and the specific insertion BPs (GO:0071816, GO:0045050). No contradictions.
  • PN story / NEW pressure: PN asserts no role beyond what GO already captures. The "Transmembrane protein import" framing is already represented by the specific, experimentally-supported insertion terms (GO:0045050, GO:0071816) plus GO:0032977. No defensible new GO term is needed; the chaperone/holdase mode (PMID:40753078, PMID:37196677) is covered via GO:0051082 in core_functions. Conclusion: already captured.
  • Mapping strategy: EMC1 does not change the node. typeβ†’GO:0072546 is correct and exact. The projected group/class terms (GO:0044743 protein transmembrane import into intracellular organelle; GO:0015031 protein transport) are BROADER than the review's specific insertion terms β€” same broader-ancestor pattern rejected for TOMM20/HSPA8/RAB7A. They are defensible as ancestor propagation but add no specificity over existing GOA.
  • Evidence alignment: Excellent overlap. Both rest on PMID:22119785 (EMC discovery), PMID:29242231 (insertase), PMID:32439656 (structure). Review adds EMC1-specific depth (CAVIPMR genetics PMID:38784058; client engagement PMID:37196677, PMID:40753078). PN cites no row-1 reference titles, so no divergence to flag.
  • Verdict: Consistent; PN adds no NEW pressure; projected group/class terms broader than review (no mapping change warranted).

PN Dossier Context

  • review_batch: proteostasis-batch-2026-06-11
  • review_yaml: genes/human/EMC1/EMC1-ai-review.yaml
  • PN workbook rows: 1

PN row 1: ER proteostasis | Protein transport | Transmembrane protein import | EMC complex component

  • UniProt: Q8N766
  • In branches: ER
  • PN-node mapping records (path + ancestors):
    • [type] ER proteostasis|Protein transport|Transmembrane protein import|EMC complex component
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0072546 EMC complex]
      rationale: This PN type denotes ER membrane protein complex components. The GO EMC complex cellular-component term is the direct target.
    • [group] ER proteostasis|Protein transport|Transmembrane protein import
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0044743 protein transmembrane import into intracellular organelle]
      rationale: This PN group covers ER transmembrane-protein insertion/import systems such as EMC- and PAT-related pathways. The local GO cache does not expose an ER-specific matching term, so the broader intracellular-organelle transmembrane-import process is the best supported propagation target.
    • [class] ER proteostasis|Protein transport
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0015031 protein transport]
      rationale: The PN ER Protein transport class groups ER-targeting and ER-insertion pathways. GO protein transport is the appropriate propagation target, while the source class remains ER-specific and broader than any single GO transport subtype.
    • [branch] ER proteostasis
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a top-level PN branch. This is a systems/taxonomy umbrella, not a direct GO assertion; narrower child curations carry any propagating GO mappings.

Projected GO annotations (3)

  • GO:0015031 protein transport | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=ER proteostasis|Protein transport
  • GO:0044743 protein transmembrane import into intracellular organelle | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=ER proteostasis|Protein transport|Transmembrane protein import
  • GO:0072546 EMC complex | scope=ok_for_propagation_to_go | goa_status=already_in_goa_exact | from=ER proteostasis|Protein transport|Transmembrane protein import|EMC complex component

Note

This file is generated from the current PROTEOSTASIS phase-1 dossier and local gene-review artifacts. Edit the source review, PN mapping, or dossier rather than this generated note when correcting the underlying curation.

πŸ“„ View Raw YAML

 
id: Q8N766
gene_symbol: EMC1
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: EMC1 (ER membrane protein complex subunit 1) is the large lumenal scaffold subunit of the endoplasmic reticulum membrane protein complex (EMC), a conserved nine- to ten-subunit transmembrane-domain insertase and chaperone of the ER. The 993-residue protein has a cleaved N-terminal signal peptide, an extensive lumenal region (~residues 23-962) that folds into a GOLD-like/WD40-YVTN beta-propeller, a single C-terminal transmembrane helix, and a short cytoplasmic tail, making it a single-pass type I membrane protein. As part of the EMC it enables the energy-independent insertion of newly synthesized membrane proteins into the ER membrane, with a preference for transmembrane domains that are weakly hydrophobic or carry destabilizing charged or aromatic residues. The complex inserts tail-anchored proteins post-translationally and inserts the first transmembrane domains of multipass proteins such as G protein-coupled receptors co-translationally, setting their N-exo topology in cooperation with the Sec61 translocon. The catalytic insertion vestibule of the complex is formed by the EMC3 and EMC6 subunits; EMC1 itself is non-catalytic and serves as a lumenal structural scaffold and assembly platform. EMC1 is broadly expressed and resides in the ER membrane, and biallelic or monoallelic variants cause CAVIPMR (cerebellar atrophy, visual impairment, and psychomotor retardation), an autosomal recessive neurodegenerative disorder.
alternative_products:
- name: '1'
  id: Q8N766-1
- name: '2'
  id: Q8N766-2
  sequence_note: VSP_020328
- name: '3'
  id: Q8N766-3
  sequence_note: VSP_020329
- name: '4'
  id: Q8N766-4
  sequence_note: VSP_020327
existing_annotations:
- term:
    id: GO:0072546
    label: EMC complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: EMC1 is a constitutive subunit of the ER membrane protein complex (EMC); the phylogenetic (IBA) assignment of EMC complex membership matches the experimentally demonstrated composition and is a core localization/complex annotation.
    action: ACCEPT
    reason: Core complex membership; EMC1 is the large lumenal scaffold subunit of the EMC, supported experimentally and conserved across the EMC1 family.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: Component of the ER membrane protein complex (EMC).
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Electronic transfer of the UniProt subcellular location to ER membrane, consistent with direct experimental localization evidence.
    action: ACCEPT
    reason: Correct compartment; EMC1 is an ER membrane protein, redundant with IDA evidence.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Endoplasmic reticulum membrane'
- term:
    id: GO:0072546
    label: EMC complex
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: part_of
  review:
    summary: InterPro-based electronic assignment of EMC complex membership, consistent with the experimental IDA/IBA annotations.
    action: ACCEPT
    reason: Correct; EMC1 is a defining EMC subunit, redundant with stronger evidence.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: Component of the ER membrane protein complex (EMC).
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32353859
  qualifier: enables
  review:
    summary: High-throughput SARS-CoV-2 affinity-purification interactome capturing an interaction between EMC1 and the viral ORF8 protein (P0DTC8). The bare protein binding term is uninformative and the partner is a viral xenobiotic protein, not a core EMC functional interaction.
    action: KEEP_AS_NON_CORE
    reason: Records a real virus-host interactome capture (EMC1 with SARS-CoV-2 ORF8) but bare protein binding is uninformative and the partner does not reflect EMC1's core ER-insertase scaffolding role; not elevated to core.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'Q8N766; P0DTC8: 8; Xeno; NbExp=3; IntAct=EBI-1044442, EBI-25475900;'
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33060197
  qualifier: enables
  review:
    summary: Comparative coronavirus host-interactome screen capturing the EMC1-SARS-CoV-2 ORF8 (P0DTC8) interaction. Bare protein binding is uninformative and the partner is a viral protein unrelated to EMC1's core function.
    action: KEEP_AS_NON_CORE
    reason: Real virus-host interactome capture but bare protein binding is uninformative; the viral partner does not inform EMC1's core ER membrane-insertase scaffolding role.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'Q8N766; P0DTC8: 8; Xeno; NbExp=3; IntAct=EBI-1044442, EBI-25475900;'
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:36217030
  qualifier: enables
  review:
    summary: Comprehensive SARS-CoV-2-human protein-protein interactome capturing the EMC1-ORF8 (P0DTC8) interaction. Bare protein binding is uninformative and the partner is a viral protein.
    action: KEEP_AS_NON_CORE
    reason: Real virus-host interactome capture; bare protein binding is uninformative and the viral partner is not part of EMC1's core insertase scaffolding function.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'Q8N766; P0DTC8: 8; Xeno; NbExp=3; IntAct=EBI-1044442, EBI-25475900;'
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: Electronic assignment of the parent endoplasmic reticulum compartment, consistent with the more specific ER membrane localization that is experimentally supported.
    action: ACCEPT
    reason: Correct compartment; EMC1 is an ER membrane protein, so the parent ER term is accurate, though GO:0005789 (ER membrane) is more informative.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Endoplasmic reticulum membrane'
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: NAS
  original_reference_id: PMID:29242231
  qualifier: located_in
  review:
    summary: ComplexPortal NAS annotation of EMC1 ER membrane localization, consistent with the direct experimental (IDA) evidence and the UniProt subcellular location.
    action: ACCEPT
    reason: Correct compartment; EMC1 resides in the ER membrane as part of the EMC, redundant with IDA evidence.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Endoplasmic reticulum membrane'
- term:
    id: GO:0045050
    label: protein insertion into ER membrane by stop-transfer membrane-anchor sequence
  evidence_type: IDA
  original_reference_id: PMID:29242231
  qualifier: involved_in
  review:
    summary: As a subunit of the EMC, EMC1 participates in the insertion of transmembrane segments (including stop-transfer/membrane-anchor sequences) into the ER membrane. This is a complex-level contribution reflecting EMC1's membership in the insertase complex.
    action: ACCEPT
    reason: Correct complex-level process annotation (involved_in); the EMC is a demonstrated transmembrane-domain insertase and EMC1 is a constitutive subunit. EMC1 itself is the non-catalytic lumenal scaffold but the process is correctly attributed to the complex.
    supported_by:
    - reference_id: PMID:29242231
      supporting_text: EMC is a transmembrane domain insertase
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: stop-transfer membrane-anchor sequences become ER membrane spanning
- term:
    id: GO:0071816
    label: tail-anchored membrane protein insertion into ER membrane
  evidence_type: IDA
  original_reference_id: PMID:29242231
  qualifier: involved_in
  review:
    summary: As a constitutive EMC subunit, EMC1 participates in the post-translational insertion of tail-anchored proteins into the ER membrane, a directly demonstrated EMC activity. This is a core complex-level process annotation; EMC1 itself is the non-catalytic lumenal scaffold.
    action: ACCEPT
    reason: Core EMC-mediated process; the EMC is a demonstrated transmembrane-domain insertase that inserts tail-anchored proteins, and EMC1 is a defining subunit.
    supported_by:
    - reference_id: PMID:29242231
      supporting_text: EMC is a transmembrane domain insertase
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: post-translational insertion of tail-anchored/TA proteins in
- term:
    id: GO:0072546
    label: EMC complex
  evidence_type: IPI
  original_reference_id: PMID:32439656
  qualifier: part_of
  review:
    summary: ComplexPortal IPI assignment of EMC complex membership based on the cryo-EM structure of the human EMC. Core structural identity of EMC1 as the large lumenal scaffold subunit.
    action: ACCEPT
    reason: Structurally demonstrated core EMC membership.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: Component of the ER membrane protein complex (EMC).
- term:
    id: GO:0032977
    label: membrane insertase activity
  evidence_type: IMP
  original_reference_id: PMID:29809151
  qualifier: contributes_to
  review:
    summary: IMP evidence (cotranslational multipass biogenesis study) that the EMC has membrane insertase activity, to which EMC1 contributes as a subunit. The contributes_to qualifier is appropriate because the catalytic insertion vestibule is formed by EMC3 and EMC6, while EMC1 is the non-catalytic lumenal scaffold that supports complex function.
    action: ACCEPT
    reason: Correct complex-level MF with contributes_to qualifier; EMC1 supports the insertase activity of the whole complex though it is not itself catalytic.
    supported_by:
    - reference_id: PMID:32439656
      supporting_text: occurs via an enclosed hydrophilic
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: enables the energy-independent insertion into endoplasmic
- term:
    id: GO:0032977
    label: membrane insertase activity
  evidence_type: IMP
  original_reference_id: PMID:30415835
  qualifier: contributes_to
  review:
    summary: IMP evidence (topogenesis study) supporting the EMC's membrane insertase activity, to which EMC1 contributes as the lumenal scaffold subunit. The contributes_to qualifier correctly reflects that EMC1 is non-catalytic while the complex performs the insertion.
    action: ACCEPT
    reason: Correct complex-level MF with contributes_to qualifier; EMC1 supports the insertase activity of the EMC.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: enables the energy-independent insertion into endoplasmic
- term:
    id: GO:0045050
    label: protein insertion into ER membrane by stop-transfer membrane-anchor sequence
  evidence_type: IMP
  original_reference_id: PMID:29809151
  qualifier: involved_in
  review:
    summary: The EMC is required for cotranslational insertion of multipass membrane proteins in which stop-transfer membrane-anchor sequences become ER membrane-spanning helices; EMC1 is a constitutive subunit of this insertase. Core EMC process.
    action: ACCEPT
    reason: Core EMC-mediated process; supported by IMP of EMC subunits in the cotranslational multipass biogenesis study.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: stop-transfer membrane-anchor sequences become ER membrane spanning
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: IDA
  original_reference_id: PMID:22119785
  qualifier: located_in
  review:
    summary: Direct experimental ER membrane localization from the foundational ERAD-network mapping study that first identified the EMC. Core compartment for EMC1.
    action: ACCEPT
    reason: Experimentally supported core location.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Endoplasmic reticulum membrane'
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: IDA
  original_reference_id: PMID:32439656
  qualifier: located_in
  review:
    summary: Direct (cryo-EM structural) evidence placing EMC1 in the ER membrane as a single-pass type I membrane subunit of the EMC. Core compartment.
    action: ACCEPT
    reason: Experimentally supported core location.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Endoplasmic reticulum membrane'
- term:
    id: GO:0045050
    label: protein insertion into ER membrane by stop-transfer membrane-anchor sequence
  evidence_type: IMP
  original_reference_id: PMID:30415835
  qualifier: involved_in
  review:
    summary: IMP evidence (topogenesis study) that the EMC inserts stop-transfer membrane-anchor sequences and sets the N-exo topology of multipass clients such as GPCRs; EMC1 is part of the insertase. Core EMC process.
    action: ACCEPT
    reason: Core EMC-mediated process.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: stop-transfer membrane-anchor sequences become ER membrane spanning
- term:
    id: GO:0032991
    label: protein-containing complex
  evidence_type: IDA
  original_reference_id: PMID:28246125
  qualifier: part_of
  review:
    summary: MGI IDA assignment of generic protein-containing complex membership, derived from the ZMPSTE24/IFITM antiviral study in which EMC1 appears as a co-purifying complex component. This is a generic parent of the specific EMC complex term and is uninformative on its own.
    action: KEEP_AS_NON_CORE
    reason: Correct but generic (a parent of GO:0072546 EMC complex); the EMC complex term captures the informative complex membership. Per guidelines an experimental IDA is retained, not removed.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: Component of the ER membrane protein complex (EMC).
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IDA
  original_reference_id: PMID:22119785
  qualifier: located_in
  review:
    summary: Direct generic membrane localization from the EMC-discovery study; a parent of the specific ER membrane term.
    action: KEEP_AS_NON_CORE
    reason: Correct but generic; the ER membrane term captures the informative localization.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Endoplasmic reticulum membrane'
- term:
    id: GO:0072546
    label: EMC complex
  evidence_type: IDA
  original_reference_id: PMID:22119785
  qualifier: part_of
  review:
    summary: Direct experimental identification of EMC1 in the EMC by the foundational ERAD-network mapping study. Core structural identity of EMC1 as the large lumenal scaffold subunit.
    action: ACCEPT
    reason: Core EMC membership; directly demonstrated.
    supported_by:
    - reference_id: file:human/EMC1/EMC1-uniprot.txt
      supporting_text: Component of the ER membrane protein complex (EMC).
core_functions:
- description: Constitutive large lumenal scaffold subunit of the ER membrane protein complex (EMC); EMC1 contributes to the complex's energy-independent membrane insertase activity that inserts transmembrane domains into the ER membrane, though the catalytic vestibule is formed by EMC3 and EMC6.
  molecular_function:
    id: GO:0032977
    label: membrane insertase activity
  in_complex:
    id: GO:0072546
    label: EMC complex
  locations:
  - id: GO:0005789
    label: endoplasmic reticulum membrane
  supported_by:
  - reference_id: file:human/EMC1/EMC1-uniprot.txt
    supporting_text: enables the energy-independent insertion into endoplasmic
  - reference_id: PMID:32439656
    supporting_text: occurs via an enclosed hydrophilic
- description: As part of the EMC, contributes to post-translational insertion of tail-anchored proteins and cotranslational insertion and N-exo topogenesis of multipass membrane proteins (including GPCRs) at the ER membrane.
  molecular_function:
    id: GO:0032977
    label: membrane insertase activity
  locations:
  - id: GO:0005789
    label: endoplasmic reticulum membrane
  supported_by:
  - reference_id: file:human/EMC1/EMC1-uniprot.txt
    supporting_text: post-translational insertion of tail-anchored/TA proteins in
  directly_involved_in:
  - id: GO:0071816
    label: tail-anchored membrane protein insertion into ER membrane
  - id: GO:0045050
    label: protein insertion into ER membrane by stop-transfer membrane-anchor sequence
- description: Within the EMC, EMC1 engages client transmembrane domains in a chaperone/holdase mode that is distinct from the EMC3/EMC6 insertase vestibule; EMC1 modulates client TMD orientation in the bilayer and stabilizes partially assembled membrane-protein complexes (e.g. CaV channel assembly intermediates).
  molecular_function:
    id: GO:0051082
    label: unfolded protein binding
  locations:
  - id: GO:0005789
    label: endoplasmic reticulum membrane
  supported_by:
  - reference_id: PMID:40753078
    supporting_text: the EMC engages TMDs via its EMC1 subunit and modulates their orientation within the lipid bilayer
  - reference_id: PMID:37196677
    supporting_text: EMC functions as a channel holdase that facilitates channel assembly
proposed_new_terms: []
suggested_questions:
- question: How do CAVIPMR-causing variants in the EMC1 lumenal beta-propeller (e.g. T82M, G868R) impair EMC assembly or client insertion, and why is the nervous system particularly vulnerable?
- question: Does the EMC1 lumenal scaffold confer client selectivity, or does it act purely structurally to position the EMC3/EMC6 catalytic core?
suggested_experiments:
- description: Reconstitute the human EMC lacking EMC1 (or carrying CAVIPMR variants) in proteoliposomes and measure insertion of tail-anchored and multipass substrates to define EMC1's structural contribution to insertase activity.
- description: Perform quantitative membrane proteomics in EMC1-knockout versus rescued neuronal cells to identify the EMC1-dependent client repertoire underlying CAVIPMR neurodegeneration.
references:
- id: PMID:32459176
  title: The architecture of EMC reveals a path for membrane protein insertion.
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: 'O''Donnell et al. 2020 (eLife). Cryo-EM architecture of the human EMC,
      establishing the overall complex organization and subunit topology relevant to
      EMC1 as a constitutive EMC subunit.'
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:22119785
  title: Defining human ERAD networks through an integrative mapping strategy.
  findings:
  - statement: Affinity-MS ERAD-network mapping that first identified the EMC (including EMC1) in human cells and localized it to the ER membrane.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Foundational identification of the human EMC; source of EMC complex membership and ER membrane localization for EMC1.
- id: PMID:28246125
  title: ZMPSTE24 defends against influenza and other pathogenic viruses.
  findings:
  - statement: Antiviral study of ZMPSTE24/IFITM; EMC1 appears only as a co-purifying generic protein-containing complex component (MGI IDA), not as a functional subject.
    reference_section_type: RESULTS
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Paper is about ZMPSTE24 antiviral defense; the EMC1 GO:0032991 annotation is an incidental generic complex co-purification, a parent of the EMC complex term.
- id: PMID:29242231
  title: The ER membrane protein complex is a transmembrane domain insertase.
  findings:
  - statement: The EMC is a transmembrane domain insertase that post-translationally inserts tail-anchored membrane proteins; reconstituted in liposomes.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Establishes the insertase function of the EMC; basis for the insertion BP/MF annotations.
- id: PMID:29809151
  title: The ER membrane protein complex interacts cotranslationally to enable biogenesis
    of multipass membrane proteins.
  findings:
  - statement: The EMC engages multipass membrane protein clients cotranslationally to enable their biogenesis.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cotranslational multipass biogenesis role of the EMC.
- id: PMID:30415835
  title: EMC Is Required to Initiate Accurate Membrane Protein Topogenesis.
  findings:
  - statement: The EMC sets the N-exo topology of the first TMD of GPCRs and other multipass proteins, cooperating with Sec61.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Topogenesis/orientation role of the EMC; GPCR clients.
- id: PMID:32353859
  title: A SARS-CoV-2 protein interaction map reveals targets for drug repurposing.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: High-throughput virus-host interactome; source of an IPI protein-binding annotation (viral ORF8/P0DTC8).
- id: PMID:32439656
  title: Structural basis for membrane insertion by the human ER membrane protein
    complex.
  findings:
  - statement: Cryo-EM structure of the human EMC; substrate insertion occurs via an enclosed hydrophilic vestibule formed by EMC3 and EMC6, while EMC1 is the large lumenal scaffold subunit.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Structural basis for the EMC; confirms EMC1 is the non-catalytic lumenal scaffold. Abstract-only in cache.
- id: PMID:33060197
  title: Comparative host-coronavirus protein interaction networks reveal pan-viral
    disease mechanisms.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Comparative coronavirus interactome; source of an IPI protein-binding annotation (viral ORF8/P0DTC8).
- id: PMID:36217030
  title: A comprehensive SARS-CoV-2-human protein-protein interactome reveals COVID-19
    pathobiology and potential host therapeutic targets.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Comprehensive SARS-CoV-2-human interactome; source of an IPI protein-binding annotation (viral ORF8/P0DTC8).
- id: PMID:37196677
  title: "EMC chaperone-Ca(V) structure reveals an ionΒ channel assembly intermediate."
  findings:
  - statement: Cryo-EM structures of human EMC bound to a CaV1.2-CaVbeta3 assembly intermediate define EMC client-binding sites (transmembrane and cytoplasmic docks), with EMC1 contributing to the TM dock that engages the channel; EMC acts as a holdase/chaperone whose binding is mutually exclusive with CaValpha2delta, indicating an ordered hand-off during channel assembly.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: PubMed-verified (Nature 2023, 619:410-419). First mammalian EMC-client structure; directly implicates the EMC1 lumenal/TM region in client docking and establishes the EMC holdase/chaperone mode beyond simple insertion. Supports EMC1's client-engagement scaffold role.
- id: PMID:37199759
  title: A selectivity filter in the ER membrane protein complex limits protein misinsertion
    at the ER.
  findings:
  - statement: Mapping of a tail-anchored substrate's path through the EMC reveals cytosolic capture by methionine-rich loops and insertion through a hydrophilic vestibule whose positively charged entrance acts as a charge-repulsion selectivity filter that rejects mitochondrial TA proteins and enforces the positive-inside topology rule.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: PubMed-verified (J Cell Biol 2023, 222:e202212007). Refines the EMC insertion/topogenesis mechanism (selectivity filter) underlying the EMC1-containing complex; complex-level rather than EMC1-specific.
- id: PMID:38517390
  title: Structural insights into human EMC and its interaction with VDAC.
  findings:
  - statement: Cryo-EM structures of human EMC in apo and VDAC-bound states (3.47 A and 3.32 A) identify a gating plug within the hydrophilic vestibule and a conserved EMC-VDAC interaction at mitochondria-ER contact sites; the VDAC-bound state appears not to be insertion-competent, supporting EMC multifunctionality.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: PubMed-verified (Aging (Albany NY) 2024, 16:5501-5525). Human EMC structures (EMC1 is the large lumenal subunit) and a new ER-mitochondria contact-site interaction with VDAC; complex-level structural context for EMC1.
- id: PMID:38784058
  title: Tribal Founder EMC1 Variant in 5 Kuwaiti Families Expands Phenotypic Spectrum
    of EMC1-Related Disorder.
  findings:
  - statement: Eight individuals from 5 Kuwaiti families homozygous for the EMC1 c.245C>T (p.Thr82Met) variant present with CAVIPMR (OMIM #616875); shared features include global developmental delay (8/8), microcephaly (8/8), truncal hypotonia (8/8), visual impairment (7/7), and failure to thrive (7/7), with chorea newly added to the phenotypic spectrum.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: PubMed-verified (Neurol Genet 2024, 10:e200156). EMC1-specific human genetics; expands the CAVIPMR phenotype and confirms p.Thr82Met pathogenicity, directly supporting EMC1's essential neurodevelopmental role.
- id: PMID:40753078
  title: The EMC acts as a chaperone for membrane proteins.
  findings:
  - statement: Interactomics and model-protein studies define an EMC chaperone function distinct from its insertase activity; the EMC engages client transmembrane domains via its EMC1 subunit and modulates their orientation in the lipid bilayer, with productive assembly reducing binding to the EMC chaperone site.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: PubMed-verified (Nat Commun 2025, 16:7097). Directly implicates EMC1 as the subunit engaging client TMDs in the EMC chaperone mode, strengthening EMC1's specific client-engagement role beyond a purely structural lumenal scaffold.