id: Q5BKT4
gene_symbol: ALG10
product_type: PROTEIN
status: INITIALIZED
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  ALG10 (ALG10A) is an endoplasmic reticulum membrane, multi-pass
  alpha-1,2-glucosyltransferase (EC 2.4.1.256) that catalyzes the final,
  glucose-capping step of dolichol-linked oligosaccharide (LLO) assembly. Acting on
  the lumenal face of the ER, it transfers glucose from dolichyl-phosphate-glucose
  (Dol-P-Glc, not UDP-Glc) onto the Glc2Man9GlcNAc2-PP-dolichol intermediate, adding
  the third and terminal alpha-1,2-linked glucose to produce the mature, fully
  assembled Glc3Man9GlcNAc2-PP-dolichol precursor. This mature glycan is the substrate
  transferred en bloc by the oligosaccharyltransferase (OST) complex onto asparagine
  residues of nascent polypeptides during protein N-linked glycosylation; the terminal
  glucose added by ALG10 is the key recognition signal for efficient OST transfer, and
  its subsequent glucosidase trimming feeds the calnexin/calreticulin glycoprotein
  quality-control cycle. ALG10 belongs to the ALG10 glucosyltransferase family
  (CAZy GT59).
existing_annotations:
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: >-
      Phylogenetically-inferred ER localization. ALG10 is a multi-pass ER membrane
      enzyme whose catalytic (LLO glucosylation) activity occurs at the ER; this is
      consistent with UniProt. Correct but less specific than the ER membrane term.
    action: ACCEPT
    reason: >-
      UniProt records ALG10 as an endoplasmic reticulum membrane protein, and LLO
      assembly is an ER-localized process. IBA localization to the ER is well supported
      by the family and by the multi-pass membrane topology.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "operates in the biosynthetic pathway of"
- term:
    id: GO:0006487
    label: protein N-linked glycosylation
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: >-
      Core biological process. ALG10 completes assembly of the LLO precursor that OST
      transfers to asparagine residues of nascent proteins, so it is directly required
      for protein N-linked glycosylation.
    action: ACCEPT
    reason: >-
      The IBA inference (drawn from broadly conserved ALG10 orthologs) matches UniProt's
      description of ALG10's role in producing the glycan precursor used in protein
      asparagine (N)-glycosylation. This is a core function of the gene.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "adds the third and last glucose residue from dolichyl phosphate glucose"
- term:
    id: GO:0106073
    label: dolichyl pyrophosphate Glc2Man9GlcNAc2 alpha-1,2-glucosyltransferase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Core molecular function. This is the Dol-P-Glc-dependent alpha-1,2-glucosyltransferase
      activity (EC 2.4.1.256, RHEA:29543) that adds the third/terminal glucose to
      Glc2Man9GlcNAc2-PP-dolichol, yielding Glc3Man9GlcNAc2-PP-dolichol.
    action: ACCEPT
    reason: >-
      This is the defining catalytic activity of ALG10, supported by UniProt (EC
      2.4.1.256, RHEA:29543) and the phylogenetic inference across ALG10 orthologs. It
      is the correct, specific molecular function term.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "Glc(2)Man(9)GlcNAc(2)-PP-Dol to produce Glc(3)Man(9)GlcNAc(2)-PP-Dol."
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      ER membrane localization from UniProt subcellular-location mapping. ALG10 is a
      multi-pass ER membrane protein (10 predicted transmembrane helices).
    action: ACCEPT
    reason: >-
      UniProt SUBCELLULAR LOCATION records ALG10 as an endoplasmic reticulum membrane,
      multi-pass membrane protein, consistent with its role as an integral ER membrane
      glucosyltransferase. This is the appropriate, specific cellular component.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "Endoplasmic reticulum membrane"
- term:
    id: GO:0006488
    label: dolichol-linked oligosaccharide biosynthetic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: >-
      Core biological process. ALG10 performs the terminal glucosylation step of
      dolichol-linked oligosaccharide biosynthesis, producing the mature
      Glc3Man9GlcNAc2-PP-dolichol.
    action: ACCEPT
    reason: >-
      InterPro2GO mapping (IPR016900, Alg10) to LLO biosynthesis is accurate and, in
      fact, is the most specific pathway term for ALG10's role; supported by UniProt's
      description of the dolichol-linked oligosaccharide assembly pathway.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "operates in the biosynthetic pathway of"
- term:
    id: GO:0106073
    label: dolichyl pyrophosphate Glc2Man9GlcNAc2 alpha-1,2-glucosyltransferase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: >-
      Same core molecular function as the IBA annotation, here derived electronically
      from EC 2.4.1.256 / RHEA:29543 / InterPro IPR016900.
    action: ACCEPT
    reason: >-
      Correct and consistent with the IBA and ISS annotations of the same term; the
      EC/RHEA/InterPro basis matches UniProt's catalytic-activity record.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "Glc(2)Man(9)GlcNAc(2)-PP-Dol to produce Glc(3)Man(9)GlcNAc(2)-PP-Dol."
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: >-
      Bare "protein binding" from the HuRI high-throughput binary (yeast two-hybrid)
      interactome screen (interaction with CD79A, UniProtKB:P11912). This is an
      uninformative molecular function term that does not describe ALG10's actual
      activity.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "protein binding" (GO:0005515) conveys no specific functional information and this
      interaction comes from a systematic proteome-wide screen rather than a targeted
      study of ALG10 function. Per curation policy the experimental annotation is not
      removed, but it is flagged as an over-annotation relative to ALG10's core
      glucosyltransferase function.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: >-
      Bare "protein binding" from the HuRI binary interactome screen (interaction with
      FBLN1, UniProtKB:P23142-4). Uninformative MF term from a systematic screen.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      As above: high-throughput binary interaction, not a specific function; retained as
      experimental but flagged over-annotated. Does not inform ALG10's core molecular
      function.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: >-
      Bare "protein binding" from the HuRI binary interactome screen (interaction with
      SHISAL1, UniProtKB:Q3SXP7). Uninformative MF term from a systematic screen.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput binary interaction; uninformative "protein binding" not describing
      ALG10's actual activity. Retained as experimental but flagged over-annotated.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: >-
      Bare "protein binding" from the HuRI binary interactome screen (interaction with
      SERP2, UniProtKB:Q8N6R1). Uninformative MF term from a systematic screen.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput binary interaction; uninformative "protein binding". Retained as
      experimental but flagged over-annotated relative to the core glucosyltransferase
      function.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: >-
      Bare "protein binding" from the HuRI binary interactome screen (interaction with
      HERPUD2, UniProtKB:Q9BSE4). Uninformative MF term from a systematic screen.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput binary interaction; uninformative "protein binding". Retained as
      experimental but flagged over-annotated.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: >-
      Bare "protein binding" from the HuRI binary interactome screen (interaction with
      ERGIC3, UniProtKB:Q9Y282). Uninformative MF term from a systematic screen.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput binary interaction; uninformative "protein binding". Retained as
      experimental but flagged over-annotated relative to ALG10's core function.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: located_in
  review:
    summary: >-
      ER membrane localization transferred by sequence similarity from the ortholog
      (UniProtKB:Q5I7T1). Consistent with UniProt and with the multi-pass membrane
      topology.
    action: ACCEPT
    reason: >-
      Agrees with the IEA SubCell ER membrane annotation and UniProt subcellular
      location; the appropriate, specific cellular component for this integral ER
      membrane enzyme.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "Endoplasmic reticulum membrane"
- term:
    id: GO:0106073
    label: dolichyl pyrophosphate Glc2Man9GlcNAc2 alpha-1,2-glucosyltransferase activity
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: >-
      Core molecular function transferred by sequence similarity from the ortholog
      (UniProtKB:Q5I7T1); same activity as the IBA/IEA annotations.
    action: ACCEPT
    reason: >-
      Consistent with the IBA and IEA annotations of GO:0106073 and with UniProt's
      catalytic-activity record (EC 2.4.1.256, RHEA:29543). Correct and specific.
    supported_by:
    - reference_id: file:human/ALG10/ALG10-uniprot.txt
      supporting_text: "Glc(2)Man(9)GlcNAc(2)-PP-Dol to produce Glc(3)Man(9)GlcNAc(2)-PP-Dol."
core_functions:
- description: >-
    ALG10 is the ER-lumenal, Dol-P-Glc-dependent alpha-1,2-glucosyltransferase
    (EC 2.4.1.256) that catalyzes the terminal glucose-capping step of dolichol-linked
    oligosaccharide assembly, transferring glucose from dolichyl-phosphate-glucose onto
    Glc2Man9GlcNAc2-PP-dolichol to produce the mature Glc3Man9GlcNAc2-PP-dolichol
    precursor. The terminal glucose it adds is the recognition signal for efficient
    oligosaccharyltransferase-mediated transfer of the glycan to nascent proteins,
    making ALG10 directly required for protein N-linked glycosylation. It acts as an
    integral, multi-pass endoplasmic reticulum membrane enzyme.
  molecular_function:
    id: GO:0106073
    label: dolichyl pyrophosphate Glc2Man9GlcNAc2 alpha-1,2-glucosyltransferase activity
  directly_involved_in:
  - id: GO:0006488
    label: dolichol-linked oligosaccharide biosynthetic process
  - id: GO:0006487
    label: protein N-linked glycosylation
  locations:
  - id: GO:0005789
    label: endoplasmic reticulum membrane
  supported_by:
  - reference_id: file:human/ALG10/ALG10-uniprot.txt
    supporting_text: "adds the third and last glucose residue from dolichyl phosphate glucose"
  - reference_id: file:human/ALG10/ALG10-uniprot.txt
    supporting_text: "Glc(2)Man(9)GlcNAc(2)-PP-Dol to produce Glc(3)Man(9)GlcNAc(2)-PP-Dol."
  - reference_id: file:human/ALG10/ALG10-uniprot.txt
    supporting_text: "Endoplasmic reticulum membrane"
proposed_new_terms: []
suggested_questions:
- question: >-
    Does human ALG10A functionally differ from its paralog ALG10B in the terminal
    glucosylation step, and are they redundant in vivo?
- question: >-
    Is the reported modulation of the Kv1.1 (KCNA1) potassium channel a moonlighting
    function of ALG10, or an indirect consequence of altered N-glycosylation?
suggested_experiments:
- description: >-
    In vitro glucosyltransferase assay using purified ALG10, Dol-P-Glc donor and
    Glc2Man9GlcNAc2-PP-dolichol acceptor to confirm formation of
    Glc3Man9GlcNAc2-PP-dolichol and measure kinetics.
- description: >-
    CRISPR knockout of ALG10 in human cells followed by LLO profiling
    (fluorophore-assisted carbohydrate electrophoresis / mass spectrometry) to confirm
    accumulation of the Glc2Man9GlcNAc2 intermediate and hypoglycosylation of reporter
    glycoproteins.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs
    by curator judgment of sequence similarity
  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:32296183
  title: A reference map of the human binary protein interactome.
  findings:
  - statement: >-
      ALG10 protein-binding annotations derive from the HuRI proteome-wide, systematic
      binary (yeast two-hybrid) interactome screen, not from a targeted study of ALG10
      function.
    supporting_text: "a reference map of the human protein interactome, generated systematically and comprehensively"
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      PubMed-verified HuRI interactome paper. Correctly cited for the six IPI protein
      binding annotations, but as a high-throughput binary screen it does not establish
      a specific molecular function for ALG10; these annotations are flagged as
      over-annotated.
- id: file:human/ALG10/ALG10-uniprot.txt
  title: UniProtKB Q5BKT4 ALG10 (AG10A_HUMAN) record
  findings:
  - statement: >-
      UniProt describes ALG10 as an ER membrane Dol-P-Glc-dependent
      alpha-1,2-glucosyltransferase (EC 2.4.1.256) that adds the third and terminal
      glucose to Glc2Man9GlcNAc2-PP-dolichol, producing mature Glc3Man9GlcNAc2-PP-dolichol
      for protein N-glycosylation.
    supporting_text: "adds the third and last glucose residue from dolichyl phosphate glucose"
  - statement: >-
      ALG10 is an endoplasmic reticulum membrane, multi-pass membrane protein belonging
      to the ALG10 glucosyltransferase family.
    supporting_text: "Belongs to the ALG10 glucosyltransferase family."
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Primary source for ALG10 function, catalytic activity, pathway and localization
      used throughout this review.