id: P02489
gene_symbol: CRYAA
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  Alpha-crystallin A chain (CRYAA/HSPB4) is a member of the small heat shock protein
  (sHSP) family
  that serves dual roles as a major structural component of the ocular lens and as
  a molecular
  chaperone with holdase activity. CRYAA forms large oligomeric complexes (approximately
  540 kDa)
  that suppress nonspecific aggregation of destabilized proteins under stress conditions
  including
  heat, UV irradiation, and chemical modification (PMID:8943244). Critically, CRYAA
  acts as a
  holdase rather than a foldase -- it prevents aggregation of partially unfolded proteins
  but does
  NOT actively refold them (as documented by the NOT annotation to GO:0042026 protein
  refolding,
  ISS from bovine ortholog). CRYAA hetero-oligomerizes with CRYAB (HSPB5) and contributes
  to lens
  transparency and refractive index. Post-translational modifications including phosphorylation
  at
  T148 (mediated by mTORC2) regulate chaperone capacity. Mutations in CRYAA (e.g.,
  R116H, R116C)
  cause autosomal dominant congenital cataracts through loss of chaperone activity
  and increased
  protein aggregation (PMID:18407550). CRYAA also has anti-apoptotic activity, binding
  and
  sequestering pro-apoptotic Bax and Bcl-X(S) proteins (PMID:14752512).
existing_annotations:
- term:
    id: GO:0043066
    label: negative regulation of apoptotic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for negative regulation of apoptotic process. CRYAA has well-documented
      anti-apoptotic activity. PMID:14752512 demonstrated that alphaA- and alphaB-crystallins
      bind to pro-apoptotic Bax and Bcl-X(S) proteins via GST pulldown and coimmunoprecipitation,
      preventing their translocation from cytosol to mitochondria during staurosporine-induced
      apoptosis. The R116C cataract mutant shows much weaker affinity to Bax and Bcl-X(S)
      (PMID:14752512). PMID:14512969 showed that the R49C mutant failed to protect
      lens epithelial
      cells from staurosporine-induced apoptosis. The IBA annotation is phylogenetically
      appropriate
      for sHSP family members with anti-apoptotic activity. This is a secondary/non-core
      function
      for CRYAA beyond its primary structural and chaperone roles.
    action: KEEP_AS_NON_CORE
    reason: >-
      Anti-apoptotic activity is well-supported by direct experimental evidence from
      PMID:14752512
      and PMID:14512969, and the IBA annotation is phylogenetically sound. However,
      this is a
      secondary function compared to the core structural and chaperone holdase roles
      in the lens.
    supported_by:
    - reference_id: PMID:14752512
      supporting_text: >-
        alphaA- and alphaB-crystallins prevent staurosporine-induced apoptosis through
        interactions with members of the Bcl-2 family
    - reference_id: PMID:14752512
      supporting_text: >-
        alpha-crystallins bind to Bax and Bcl-X(S) both in vitro and in vivo
    - reference_id: PMID:14512969
      supporting_text: >-
        unlike wild-type CRYAA, the R49C mutant protein was abnormally localized to
        the nucleus
        and failed to protect from staurosporine-induced apoptotic cell death
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for cytoplasm localization. CRYAA is abundantly expressed in
      the cytoplasm
      of lens fiber cells. Multiple IDA-level studies confirm cytoplasmic localization
      including
      PMID:19464326, PMID:14752512, PMID:29259299, PMID:19503744, PMID:26004348, and
      PMID:30340470. UniProt also lists cytoplasm as a confirmed subcellular location.
      The IBA
      annotation is consistent with direct experimental evidence and is phylogenetically
      appropriate.
    action: ACCEPT
    reason: >-
      Cytoplasmic localization is the primary location of CRYAA, confirmed by multiple
      independent
      IDA studies using fluorescence microscopy in lens epithelial cells and other
      cell types. The
      IBA annotation is well supported.
    supported_by:
    - reference_id: PMID:29259299
      supporting_text: >-
        Wild-type alphaA-crystallin was also equally distributed in the cytoplasm
    - reference_id: PMID:14752512
      supporting_text: >-
        alpha-crystallins prevent the translocation of Bax and Bcl-X(S) from cytosol
        into
        mitochondria during staurosporine-induced apoptosis
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for nucleus localization. UniProt notes that CRYAA (HSPB4)
      translocates to the nucleus during heat shock and resides in SC35 splicing
      speckles. This is a stress-induced secondary localization rather than the
      primary constitutive location. The
      IBA annotation is phylogenetically appropriate for sHSP family members that
      show nuclear
      translocation under stress.
    action: KEEP_AS_NON_CORE
    reason: >-
      Nuclear localization is real but conditional (stress-induced). UniProt records
      CRYAA translocation to SC35 splicing speckles during heat shock. This is not
      the primary constitutive
      localization of CRYAA, which is cytoplasmic. Keeping as non-core reflects that
      this is a
      secondary, stress-dependent localization.
    supported_by:
    - reference_id: UniProtKB:P02489
      supporting_text: >-
        Nucleus. Note=Translocates to the nucleus during heat shock and resides
        in sub-nuclear structures known as SC35 speckles or nuclear splicing
        speckles.
- term:
    id: GO:0009408
    label: response to heat
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for response to heat. CRYAA is a member of the small heat shock
      protein
      (sHSP) family and its chaperone-like activity was explicitly demonstrated using
      heat-induced
      aggregation assays (PMID:8943244). The protein suppresses heat-induced aggregation
      of aldose
      reductase and other lens proteins. CRYAA also translocates to nuclear SC35 speckles
      during
      heat shock (PMID:19464326). The IBA annotation is phylogenetically appropriate
      for the sHSP
      family whose hallmark is response to heat stress.
    action: ACCEPT
    reason: >-
      Response to heat is a core function of sHSP family members. CRYAA suppresses
      heat-induced
      protein aggregation (PMID:8943244) and shows heat-shock-dependent nuclear translocation
      (PMID:19464326). The IBA annotation is well justified for the sHSP family.
    supported_by:
    - reference_id: PMID:8943244
      supporting_text: >-
        both WT and W9F subunits completely suppressed the heat-induced aggregation
        of aldose
        reductase
    - reference_id: file:human/CRYAA/CRYAA-deep-research-falcon.md
      supporting_text: >-
        As a chaperone, HSPB4 binds partially unfolded proteins to prevent
        misfolding and aggregation, thereby maintaining lens proteostasis and
        cell survival
- term:
    id: GO:0042026
    label: protein refolding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for protein refolding. This is problematic for CRYAA. While some
      sHSP family
      members can assist in protein refolding (e.g., HSPB1/Hsp27 cooperates with Hsp70
      to refold
      substrates), CRYAA specifically acts as a holdase that prevents aggregation
      but does NOT
      refold proteins. This is documented by the NOT annotation to GO:0042026 (ISS
      from bovine
      ortholog, GO_REF:0000024). The IBA propagation from the broader sHSP family
      is overly
      broad for CRYAA, which lacks foldase activity. PMID:19464326 showed that HSPB1
      and HSPB5
      kept heat-unfolded substrates folding-competent, but HSPB7 did not support refolding,
      highlighting functional divergence within the family. CRYAA has holdase but
      not foldase
      activity.
    action: REMOVE
    reason: >-
      CRYAA is a holdase, not a foldase. It prevents aggregation of denatured proteins
      but does
      not refold them. The NOT annotation to GO:0042026 (ISS, GO_REF:0000024) explicitly
      documents this. The IBA propagation from the broader sHSP family is incorrect
      for CRYAA
      because not all sHSP members have refolding activity. There is functional divergence
      within the family (PMID:19464326).
    supported_by:
    - reference_id: PMID:8943244
      supporting_text: >-
        alpha-crystallin subunits associate to form large oligomeric aggregates that
        express
        chaperone-like activity, as defined by the ability to suppress nonspecific
        aggregation
        of proteins destabilized by treatment with a variety of denaturants
    - reference_id: PMID:19464326
      supporting_text: >-
        Unlike HSPB1 and HSPB5, that chaperoned heat unfolded substrates and kept
        them folding
        competent, HSPB7 did not support refolding
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      GO:0051082 "unfolded protein binding" is being obsoleted (go-ontology#30962).
      CRYAA/HSPB4 does
      interact with partially unfolded/destabilized proteins, but the term "unfolded
      protein binding"
      is problematic because it implies a simple binding function rather than the
      active chaperone
      holdase activity that CRYAA performs. CRYAA suppresses nonspecific aggregation
      of destabilized
      proteins (PMID:8943244) but does NOT refold them -- it is a holdase, not a foldase.
      The IBA
      annotation is phylogenetically propagated from sHSP family members across Drosophila,
      zebrafish,
      and mammals, which is appropriate for the family-level chaperone function. However,
      the term
      itself needs replacement. GO:0140309 "unfolded protein carrier activity" is
      the appropriate MF term for ATP-independent binding to unfolded proteins to
      prevent their aggregation without active refolding. As a biological process
      annotation, GO:0050821 "protein stabilization"
      (defined as
      "Any process involved in maintaining the structure and integrity of a protein
      and preventing it
      from degradation or aggregation") is also relevant and is already annotated
      for CRYAA via
      PMID:12235146.
    action: MODIFY
    reason: >-
      GO:0051082 is being obsoleted. CRYAA has well-documented chaperone-like holdase
      activity:
      it suppresses aggregation of heat-denatured aldose reductase and singlet-oxygen-damaged
      gamma-crystallin (PMID:8943244). However, it does NOT refold proteins (NOT annotation
      to
      GO:0042026 protein refolding, ISS). The appropriate MF replacement is
      GO:0140309 "unfolded protein carrier activity." GO:0050821 "protein
      stabilization" is appropriate as a BP term.
    proposed_replacement_terms:
    - id: GO:0140309
      label: unfolded protein carrier activity
    additional_reference_ids:
    - PMID:8943244
    - PMID:18407550
    supported_by:
    - reference_id: PMID:8943244
      supporting_text: >-
        alpha-crystallin subunits associate to form large oligomeric aggregates that
        express
        chaperone-like activity, as defined by the ability to suppress nonspecific
        aggregation of
        proteins destabilized by treatment with a variety of denaturants including
        heat, UV
        irradiation, and chemical modification
    - reference_id: PMID:8943244
      supporting_text: >-
        both WT and W9F subunits completely suppressed the heat-induced aggregation
        of aldose
        reductase
- term:
    id: GO:0002088
    label: lens development in camera-type eye
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      IBA annotation for lens development in camera-type eye. CRYAA is the most abundantly
      expressed protein in the ocular lens and is essential for normal lens development
      and
      transparency. UniProt states it is expressed in the eye lens (PubMed:12356833,
      PubMed:23255486).
      Knockout studies in zebrafish show abnormal differentiation of lens fiber cells
      when
      alpha-crystallins are absent (cited in PMID:29259299). Numerous CRYAA mutations
      cause
      congenital cataracts (PMID:9467006, PMID:14512969, PMID:18407550), demonstrating
      the essential
      role in lens development. The IBA annotation is appropriate for crystallin family
      members
      involved in lens development.
    action: ACCEPT
    reason: >-
      CRYAA is a core lens protein essential for normal lens development. Mutations
      consistently
      cause congenital cataracts (PMID:9467006, PMID:14512969, PMID:18407550). The
      IBA annotation
      appropriately captures this conserved developmental role.
    supported_by:
    - reference_id: PMID:14512969
      supporting_text: >-
        The alphaA-crystallin (CRYAA) gene (CRYAA) encodes a member of the small-heat-shock
        protein (sHSP) family of molecular chaperones and is primarily and abundantly
        expressed
        in the ocular lens
    - reference_id: PMID:9467006
      supporting_text: >-
        we found that a missense mutation, R116C, is associated with ADCC in this
        family
- term:
    id: GO:0005198
    label: structural molecule activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  review:
    summary: >-
      IEA annotation for structural molecule activity. CRYAA is a major structural
      protein of the
      eye lens contributing to transparency and refractive index (UniProt FUNCTION
      section). While
      correct, the more specific child term GO:0005212 "structural constituent of
      eye lens" is
      also annotated and is more informative. This broader IEA term is acceptable
      as a parent term
      but less informative than the specific one.
    action: MODIFY
    reason: >-
      While structural molecule activity is correct for CRYAA as a major structural
      lens protein,
      the more specific child term GO:0005212 "structural constituent of eye lens"
      is already
      annotated and is more informative. Modifying to the specific term for consistency
      with
      the IDA annotation review of the same GO term.
    proposed_replacement_terms:
    - id: GO:0005212
      label: structural constituent of eye lens
- term:
    id: GO:0005212
    label: structural constituent of eye lens
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      IEA annotation for structural constituent of eye lens. This is one of the most
      appropriate
      terms for CRYAA. As alphaA-crystallin, it is the most abundant soluble protein
      in the lens,
      contributing to transparency and refractive index (UniProt FUNCTION: "Contributes
      to the
      transparency and refractive index of the lens"). The IEA mapping is accurate
      and captures
      a core function.
    action: ACCEPT
    reason: >-
      CRYAA is the defining structural constituent of the eye lens. This is a core
      function
      annotation. UniProt documents that CRYAA contributes to transparency and refractive
      index
      of the lens, confirmed by the fact that mutations cause cataracts (PMID:9467006,
      PMID:18407550).
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: >-
      IEA annotation for nucleus based on UniProt subcellular location mapping. UniProt
      lists
      nucleus as a confirmed subcellular location, noting that CRYAA translocates
      to the nucleus
      during heat shock and resides in SC35 speckles (PMID:19464326). The IEA mapping
      is correct
      and consistent with the IBA and IDA annotations for the same term. However,
      nuclear
      localization is stress-induced and secondary, not constitutive.
    action: KEEP_AS_NON_CORE
    reason: >-
      The IEA mapping from UniProt subcellular location is accurate. Nuclear localization
      is
      supported by PMID:19464326 showing heat-shock-induced translocation to SC35
      speckles.
      However, this is a stress-dependent secondary localization, not the primary
      constitutive
      location of CRYAA. Marked as KEEP_AS_NON_CORE for consistency with the IBA and
      IDA
      annotations for the same GO term.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      IEA annotation for cytoplasm. Cytoplasmic localization is the primary constitutive
      location
      of CRYAA, confirmed by multiple IDA-level studies (PMID:19464326, PMID:29259299,
      PMID:19503744, PMID:14752512, etc.) and UniProt subcellular location annotation.
      The IEA
      mapping is correct.
    action: ACCEPT
    reason: >-
      Cytoplasm is the primary constitutive localization of CRYAA, well supported
      by multiple
      independent studies. The IEA is consistent with IBA and IDA annotations.
- term:
    id: GO:0007601
    label: visual perception
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >-
      IEA annotation for visual perception based on UniProt keyword mapping. CRYAA
      is essential
      for lens transparency, and mutations cause cataracts that impair vision (PMID:9467006,
      PMID:14512969). However, CRYAA does not directly participate in the visual perception
      signaling pathway (phototransduction). Rather, it maintains the structural integrity
      of
      the lens through which light passes. This term is somewhat over-annotated as
      it implies
      a role in visual signaling rather than lens maintenance.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      While CRYAA is essential for lens transparency and mutations cause cataracts
      that impair
      vision, the term "visual perception" implies involvement in the phototransduction/visual
      signaling pathway. CRYAA contributes to vision indirectly by maintaining lens
      structure,
      not by participating in the perception process itself. GO:0002088 "lens development
      in
      camera-type eye" and GO:0005212 "structural constituent of eye lens" better
      capture the
      actual role.
- term:
    id: GO:0046872
    label: metal ion binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >-
      IEA annotation for metal ion binding from UniProt keyword mapping. UniProt documents
      that
      CRYAA binds zinc ions, with the zinc-binding motif created from residues of
      3 different
      molecules (His-100, Glu-102 from one molecule; His-107 and His-154 from additional
      molecules) to create tetrahedral coordination geometry (PMID:22890888). Inter-subunit
      bridging via zinc ions enhances oligomer stability. This is a legitimate but
      generic
      annotation; a more specific term like "zinc ion binding" (GO:0008270) would
      be more
      informative.
    action: MODIFY
    reason: >-
      Metal ion binding is too generic. The specific metal bound is zinc, which is
      important for
      oligomer stability (PMID:22890888 via UniProt). GO:0008270 "zinc ion binding"
      would be
      more informative.
    proposed_replacement_terms:
    - id: GO:0008270
      label: zinc ion binding
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:11700327
  review:
    summary: >-
      IPI annotation for protein binding from PMID:11700327. This study used a mammalian
      two-hybrid
      system to detect interactions between alphaA-crystallin and other lens crystallins
      (alphaB-,
      betaB2-, and gammaC-crystallin) and Hsp27 in HeLa cells. The interactions between
      alpha-
      crystallins and beta/gamma-crystallins were about one-third the intensity of
      alphaA-alphaB
      interactions. While the interactions are real and functionally relevant (crystallin-crystallin
      interactions maintain lens transparency), "protein binding" is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" is too vague. The actual interactions detected are crystallin-crystallin
      interactions, not direct evidence for a specific molecular-function replacement.
      CRYAA holdase activity is supported by aggregation-suppression assays elsewhere;
      this two-hybrid interaction record should not be used to infer a chaperone term.
    supported_by:
    - reference_id: PMID:11700327
      supporting_text: >-
        there were interactions between alphaA- (or alphaB-) and betaB2- or gammaC-crystallins
        but with an intensity of one-third that of alphaA-alphaB interactions
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:12601044
  review:
    summary: >-
      IPI annotation for protein binding from PMID:12601044. This study used the mammalian
      two-hybrid system to show that cataract-causing R116C alphaA-crystallin mutant
      has altered
      protein-protein interactions with crystallins. The wild-type CRYAA interactions
      with betaB2-
      and gammaC-crystallin decreased in the R116C mutant, while interactions with
      alphaB-crystallin
      and Hsp27 increased. "Protein binding" is uninformative for the functional context.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" is too generic. The crystallin-crystallin interactions documented
      are
      functionally relevant to lens protein organization, but altered two-hybrid
      interactions in a cataract mutant are not direct evidence for a chaperone
      molecular-function replacement. Keep the mechanistic context without treating
      generic protein binding as a core function.
    supported_by:
    - reference_id: PMID:12601044
      supporting_text: >-
        for the R116C alphaA-crystallin, the interactions with betaB2- and gammaC-crystallin
        decreased and those with alphaB-crystallin and heat-shock protein (Hsp)27
        increased
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19651604
  review:
    summary: >-
      IPI annotation for protein binding from PMID:19651604. This study analyzed quaternary
      structures of alpha-crystallins and showed that alphaA-crystallin forms defined
      oligomers
      of 24 subunits as well as smaller oligomers and large clusters. The protein-protein
      interactions documented here are oligomerization (homo- and hetero-oligomerization
      with
      CRYAB), which is intrinsic to the structural and chaperone function. "Protein
      binding"
      is uninformative.
    action: MODIFY
    reason: >-
      "Protein binding" is too vague. The interactions are homo-oligomerization and
      hetero-
      oligomerization relevant to CRYAA structural and chaperone function. GO:0042802
      "identical
      protein binding" is already annotated from this reference, which is more specific.
    proposed_replacement_terms:
    - id: GO:0042802
      label: identical protein binding
    supported_by:
    - reference_id: PMID:19651604
      supporting_text: >-
        alphaA-Crystallin forms, in addition to complexes of 24 subunits, also smaller
        oligomers
        and large clusters consisting of individual oligomers
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22085609
  review:
    summary: >-
      IPI annotation for protein binding from PMID:22085609, which studied the F71L
      mutant of
      alphaA-crystallin. This study examined structural and functional properties
      of the cataract-
      causing mutant. The interactions documented are likely crystallin oligomerization
      relevant
      to the chaperone function. "Protein binding" is uninformative.
    action: MODIFY
    reason: >-
      "Protein binding" is too generic. The interactions documented in this paper
      are crystallin
      self-interactions (oligomerization) relevant to chaperone function. GO:0042802
      "identical
      protein binding" is already annotated from this reference.
    proposed_replacement_terms:
    - id: GO:0042802
      label: identical protein binding
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22153508
  review:
    summary: >-
      IPI annotation for protein binding from PMID:22153508, which studied the polyhedral
      architecture of alphaB-crystallin. While primarily focused on CRYAB, interactions
      with
      CRYAA may have been detected in this study. "Protein binding" is uninformative
      and should
      be replaced with more specific terms for the alpha-crystallin hetero-oligomerization.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" is too vague. The context is alpha-crystallin oligomerization.
      A more
      specific term describing hetero-oligomerization or structural complex formation
      would be
      more informative, but GO:0042802 should not be used here because this row is
      not specific to CRYAA self-interaction.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:23188086
  review:
    summary: >-
      IPI annotation for protein binding from PMID:23188086. This study investigated
      binding
      determinants of alphaB-crystallin, specifically recognition of the IxI motif.
      The IxI
      motif is important for sHSP oligomerization and substrate interaction. Interactions
      with
      CRYAA would be in the context of hetero-oligomerization. "Protein binding" is
      uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" is too vague. The context is sHSP subunit interactions via
      the IxI
      motif, relevant to hetero-oligomerization with CRYAB rather than identical
      CRYAA self-binding.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25416956
  review:
    summary: >-
      IPI annotation for protein binding from PMID:25416956 (proteome-scale interactome
      map).
      This is a high-throughput study. "Protein binding" from high-throughput interactome
      studies is uninformative and lacks the context of specific functional interactions.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" from high-throughput interactome mapping is too generic. CRYAA
      is known
      to form homo- and hetero-oligomers, but this broad interactome row is not
      specific enough to justify replacing the annotation with identical protein
      binding.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25910212
  review:
    summary: >-
      IPI annotation for protein binding from PMID:25910212 (macromolecular interaction
      perturbations in human genetic disorders). This is a high-throughput study examining
      how
      disease-associated mutations perturb protein interactions. "Protein binding"
      from such
      studies is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" from a high-throughput interaction perturbation study does
      not tell us
      anything specific about CRYAA function. The actual molecular functions (chaperone
      holdase,
      structural lens protein, oligomerization) are better captured by other annotations.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:29892012
  review:
    summary: >-
      IPI annotation for protein binding from PMID:29892012 (interactome perturbation
      framework
      for developmental disorders). This is a high-throughput study. "Protein binding"
      is
      uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" from a high-throughput interactome perturbation study is too
      generic
      to be informative about CRYAA function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:31515488
  review:
    summary: >-
      IPI annotation for protein binding from PMID:31515488 (disruption of protein
      interactions
      by genetic variants). This is a high-throughput study examining interaction
      perturbations.
      "Protein binding" is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" from high-throughput variant effect mapping is too generic.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  review:
    summary: >-
      IPI annotation for protein binding from PMID:32296183 (reference map of human
      binary
      protein interactome). This is a high-throughput interactome mapping study. "Protein
      binding" is uninformative. GO:0042802 is already annotated from this same reference.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" is too vague. Although GO:0042802 "identical protein binding"
      is annotated separately from this reference, this broad interactome protein-binding
      row should not itself be converted to a self-interaction assertion.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  review:
    summary: >-
      IPI annotation for protein binding from PMID:32814053 (interactome mapping of
      neurodegenerative disease proteins). This is a high-throughput study. "Protein
      binding"
      is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" from a high-throughput neurodegenerative disease interactome
      study is
      too generic. The finding that CRYAA interacts with disease-associated proteins
      could be
      relevant to its chaperone holdase function but "protein binding" does not capture
      this.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  review:
    summary: >-
      IPI annotation for protein binding from PMID:33961781 (dual proteome-scale networks
      for
      cell-specific interactome). This is a high-throughput study. "Protein binding"
      is
      uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" from a high-throughput proteome-scale interactome study is
      too generic.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:12601044
  review:
    summary: >-
      IPI annotation for identical protein binding from PMID:12601044. This study
      demonstrated
      alphaA-crystallin self-interaction using a mammalian two-hybrid system, showing
      that the
      R116C cataract mutant had altered self-interaction. Self-interaction (homo-oligomerization)
      is a core property of CRYAA -- it forms homodimers and homotetramers as building
      blocks
      of larger homo-oligomers (UniProt). This annotation appropriately captures the
      self-interaction property.
    action: ACCEPT
    reason: >-
      CRYAA homo-oligomerization is a core structural property essential for both
      its lens
      structural role and chaperone function. The R116C cataract mutation alters this
      self-
      interaction (PMID:12601044), confirming functional importance.
    supported_by:
    - reference_id: PMID:12601044
      supporting_text: >-
        for the R116C alphaA-crystallin, the interactions with betaB2- and gammaC-crystallin
        decreased and those with alphaB-crystallin and heat-shock protein (Hsp)27
        increased
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:19651604
  review:
    summary: >-
      IPI annotation for identical protein binding from PMID:19651604. This study
      demonstrated
      that alphaA-crystallin forms defined oligomers of 24 subunits as well as smaller
      oligomers
      and large clusters using biophysical methods and electron microscopy. The self-interaction
      (homo-oligomerization) is directly demonstrated.
    action: ACCEPT
    reason: >-
      CRYAA homo-oligomerization is directly demonstrated by biophysical analysis
      showing
      24-subunit oligomers (PMID:19651604). This is a core property of the protein.
    supported_by:
    - reference_id: PMID:19651604
      supporting_text: >-
        alphaA-Crystallin forms, in addition to complexes of 24 subunits, also smaller
        oligomers
        and large clusters consisting of individual oligomers
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:22085609
  review:
    summary: >-
      IPI annotation for identical protein binding from PMID:22085609. The F71L cataract-causing
      mutant study examined structural and functional properties including oligomerization.
      Self-interaction of CRYAA is documented.
    action: ACCEPT
    reason: >-
      Self-interaction (homo-oligomerization) is a core property of CRYAA confirmed
      by multiple
      studies. The F71L mutant study provides additional evidence.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:25416956
  review:
    summary: >-
      IPI annotation for identical protein binding from PMID:25416956 (proteome-scale
      interactome
      map). CRYAA-CRYAA self-interaction is documented in this high-throughput study.
      UniProt
      lists 12 experiments supporting CRYAA self-interaction (IntAct). While from
      a high-
      throughput study, the self-interaction is well validated by targeted studies.
    action: ACCEPT
    reason: >-
      CRYAA homo-oligomerization is well documented. The high-throughput detection
      confirms
      targeted studies. UniProt lists 12 experiments for CRYAA-CRYAA interaction.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  review:
    summary: >-
      IPI annotation for identical protein binding from PMID:32296183 (reference map
      of human
      binary protein interactome). CRYAA self-interaction detected in this systematic
      study.
      Consistent with extensive prior evidence for homo-oligomerization.
    action: ACCEPT
    reason: >-
      CRYAA homo-oligomerization is a well-established core property, and this high-throughput
      study provides consistent confirmatory evidence.
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: >-
      IDA annotation for nucleoplasm based on curation of immunofluorescence data
      (GO_REF:0000052). PMID:19464326 showed that CRYAA (HSPB4) translocates to the
      nucleus
      during heat shock and resides in SC35 speckles, which are nuclear sub-structures
      within
      the nucleoplasm. The nucleoplasm localization is consistent with this stress-dependent
      translocation.
    action: KEEP_AS_NON_CORE
    reason: >-
      Nucleoplasm localization is supported by evidence of heat-shock-induced translocation
      to
      SC35 speckles (PMID:19464326). However, this is a stress-dependent secondary
      localization,
      not the primary constitutive location.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: >-
      IDA annotation for cytosol based on curation of immunofluorescence data (GO_REF:0000052).
      CRYAA is a soluble cytoplasmic protein that exists free in the cytosol as oligomeric
      complexes. Multiple studies show uniform cytoplasmic distribution (PMID:29259299,
      PMID:19503744). Cytosol is a more specific sub-compartment of cytoplasm and
      is consistent
      with the known biology.
    action: ACCEPT
    reason: >-
      Cytosol is the primary constitutive location of CRYAA, where it exists as soluble
      oligomeric
      complexes. Consistent with multiple IDA studies showing cytoplasmic distribution.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:29259299
  review:
    summary: >-
      IDA annotation for cytoplasm from PMID:29259299. This study used fluorescence
      microscopy
      of GFP-tagged wild-type alphaA-crystallin in human lens epithelial cells and
      showed that
      wild-type CRYAA was equally distributed in the cytoplasm. The mutant (p.116_118del)
      accumulated at the nuclear peripheral membrane.
    action: ACCEPT
    reason: >-
      Direct fluorescence microscopy evidence showing wild-type CRYAA is uniformly
      distributed
      in the cytoplasm of human lens epithelial cells (PMID:29259299).
    supported_by:
    - reference_id: PMID:29259299
      supporting_text: >-
        Wild-type alphaA-crystallin was also equally distributed in the cytoplasm
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:26004348
  review:
    summary: >-
      IDA annotation for cytoplasm from PMID:26004348. This study on congenital cataract
      families
      included subcellular localization analysis. UniProt lists this as a supporting
      reference
      for cytoplasmic localization.
    action: ACCEPT
    reason: >-
      Cytoplasmic localization supported by localization data from PMID:26004348,
      consistent with
      the primary constitutive location of CRYAA.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:19503744
  review:
    summary: >-
      IDA annotation for cytoplasm from PMID:19503744. This study on the R12C alphaA-crystallin
      mutation characterized subcellular localization. UniProt lists this as supporting
      evidence
      for cytoplasmic localization.
    action: ACCEPT
    reason: >-
      Cytoplasmic localization is documented as the primary location in this study
      of the R12C
      mutant, consistent with multiple other studies.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:30340470
  review:
    summary: >-
      IDA annotation for cytoplasm from PMID:30340470. This study on a novel CRYAA
      mutation
      (congenital cataract and microphthalmia) included subcellular localization analysis.
      UniProt lists this as supporting evidence for cytoplasmic localization.
    action: ACCEPT
    reason: >-
      Cytoplasmic localization confirmed by this cataract mutation study, consistent
      with
      the known primary location of CRYAA.
- term:
    id: GO:0005198
    label: structural molecule activity
  evidence_type: IDA
  original_reference_id: PMID:16303126
  review:
    summary: >-
      IDA annotation for structural molecule activity from PMID:16303126. This study
      showed that
      alpha-crystallins (alphaA- and alphaB-) suppress aggregation of the cataract-causing
      T5P
      gammaC-crystallin mutant both in vitro and in transfected cells. The study demonstrated
      a dual role: increasing solubility and reducing aggregate size. However, "structural
      molecule
      activity" is not the best descriptor for this chaperone function. The paper
      is really about
      chaperone holdase activity, not structural function per se. The more specific
      term
      GO:0005212 "structural constituent of eye lens" better captures the structural
      role.
    action: MODIFY
    reason: >-
      The evidence in PMID:16303126 is about chaperone holdase activity (suppressing
      aggregation
      of T5P gammaC-crystallin), not structural molecule activity per se. GO:0140309
      "unfolded protein carrier activity" better captures the molecular function demonstrated. For
      the true
      structural role, GO:0005212 is already annotated.
    proposed_replacement_terms:
    - id: GO:0140309
      label: unfolded protein carrier activity
    supported_by:
    - reference_id: PMID:16303126
      supporting_text: >-
        the major lenticular protein chaperones, alpha A- and alpha B-crystallin,
        increased
        the solubility of the T5P gamma C-crystallin both in vitro and in transfected
        cells
    - reference_id: PMID:16303126
      supporting_text: >-
        the size of the T5P gamma C-crystallin aggregates were also significantly
        reduced in
        the presence of the lenticular chaperones
- term:
    id: GO:0032991
    label: protein-containing complex
  evidence_type: IDA
  original_reference_id: PMID:16303126
  review:
    summary: >-
      IDA annotation for protein-containing complex from PMID:16303126. CRYAA forms
      large
      oligomeric complexes of approximately 540 kDa (PMID:8943244). UniProt documents
      that
      CRYAA forms heteropolymers (3 CRYAA : 1 CRYAB), homodimers, homotetramers, and
      larger
      homo-oligomers. It is also part of a complex with BFSP1 and BFSP2 for lens intermediate
      filament formation. The protein-containing complex annotation is correct but
      very generic.
    action: ACCEPT
    reason: >-
      CRYAA forms large homo- and hetero-oligomeric complexes as a core feature of
      its biology.
      The annotation is correct, though generic. The oligomeric complex is essential
      for both
      structural and chaperone functions.
    supported_by:
    - reference_id: PMID:8943244
      supporting_text: >-
        aggregates of approximately 540 kDa were formed from a tryptophan-free alphaA
        mutant
        (W9F)
    - reference_id: PMID:16303126
      supporting_text: >-
        the major lenticular protein chaperones, alpha A- and alpha B-crystallin,
        increased the
        solubility of the T5P gamma C-crystallin both in vitro and in transfected
        cells
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:16303126
  review:
    summary: >-
      IPI annotation for identical protein binding from PMID:16303126. This study
      used both
      in vitro sedimentation assays and cell transfection to demonstrate that alpha-crystallins
      form complexes. CRYAA homo-oligomerization is well established and essential
      for function.
    action: ACCEPT
    reason: >-
      CRYAA homo-oligomerization is a core property demonstrated in this study and
      many others.
      The self-interaction is essential for forming the large oligomeric complexes
      required for
      both structural and chaperone functions.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:12235146
  review:
    summary: >-
      IPI annotation for protein binding from PMID:12235146. This study investigated
      the role of
      C-terminal extensions of alphaA- and alphaB-crystallins by domain swapping,
      demonstrating
      that the C-terminal extension plays a crucial role in structure and chaperone
      activity.
      The protein-protein interactions are alphaA-alphaB hetero-oligomerization. "Protein
      binding"
      is too generic.
    action: MODIFY
    reason: >-
      "Protein binding" is uninformative. The interactions documented are alpha-crystallin
      subunit interactions (hetero-oligomerization) relevant to chaperone function.
      GO:0140309 "unfolded protein carrier activity" better captures the molecular
      function demonstrated by the chaperone activity assays used.
    proposed_replacement_terms:
    - id: GO:0140309
      label: unfolded protein carrier activity
    supported_by:
    - reference_id: PMID:12235146
      supporting_text: >-
        Our study demonstrates that the unstructured C-terminal extensions play a
        crucial role
        in the structure and chaperone activity, in addition to generally believed
        electrostatic
        "solubilizer" function
- term:
    id: GO:0050821
    label: protein stabilization
  evidence_type: IMP
  original_reference_id: PMID:12235146
  review:
    summary: >-
      IMP annotation for protein stabilization from PMID:12235146. This study showed
      that
      domain-swapped chimeras of alphaA and alphaB crystallins have dramatically altered
      chaperone-like activity -- the chimeric alphaB with CRYAA C-terminal extension
      showed
      enhanced chaperone activity while the chimeric alphaA with CRYAB C-terminal
      extension
      almost lost activity. This demonstrates that CRYAA contributes to protein stabilization
      (preventing aggregation of destabilized proteins). GO:0050821 "protein stabilization"
      is
      defined as "any process involved in maintaining the structure and integrity
      of a protein
      and preventing it from degradation or aggregation." This is an excellent fit
      for CRYAA
      holdase activity.
    action: ACCEPT
    reason: >-
      GO:0050821 "protein stabilization" accurately describes the core holdase function
      of CRYAA
      -- preventing aggregation and maintaining protein integrity. The evidence from
      PMID:12235146
      demonstrates that the C-terminal extension of CRYAA is crucial for this function.
      This is
      one of the most appropriate BP terms for the CRYAA holdase chaperone activity.
    supported_by:
    - reference_id: PMID:12235146
      supporting_text: >-
        the chimeric alphaB with the C-terminal extension of alphaA-crystallin, alphaBAc,
        exhibits dramatically enhanced chaperone-like activity
    - reference_id: PMID:12235146
      supporting_text: >-
        the unstructured C-terminal extensions play a crucial role in the structure
        and
        chaperone activity
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:19464326
  review:
    summary: >-
      IDA annotation for nucleus from PMID:19464326. The cached abstract excerpt
      available here is about HSPB7, so explicit text support is taken from the
      UniProt CRYAA subcellular-location statement, which records heat-shock-induced
      nuclear translocation to SC35 splicing speckles. While not the primary
      constitutive localization, the stress-induced nuclear translocation is
      experimentally documented in the UniProt record.
    action: KEEP_AS_NON_CORE
    reason: >-
      Nuclear localization is stress-induced (heat shock) rather than constitutive.
      CRYAA resides in SC35 speckles under stress conditions. This is a secondary
      localization.
    supported_by:
    - reference_id: UniProtKB:P02489
      supporting_text: >-
        Nucleus. Note=Translocates to the nucleus during heat shock and resides
        in sub-nuclear structures known as SC35 speckles or nuclear splicing
        speckles.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:19464326
  review:
    summary: >-
      IDA annotation for cytoplasm from PMID:19464326. This study used confocal microscopy
      to
      characterize subcellular localization of HSPB family members and showed CRYAA
      (HSPB4)
      in the cytoplasm under basal conditions.
    action: ACCEPT
    reason: >-
      Cytoplasmic localization is directly demonstrated by confocal microscopy in
      PMID:19464326,
      consistent with the primary constitutive location of CRYAA.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:14752512
  review:
    summary: >-
      IPI annotation for protein binding from PMID:14752512. This study demonstrated
      by GST
      pulldown and coimmunoprecipitation that alphaA-crystallin binds to pro-apoptotic
      Bax and
      Bcl-X(S) proteins both in vitro and in vivo, preventing their translocation
      to mitochondria
      during staurosporine-induced apoptosis. The R116C cataract mutant showed much
      weaker
      affinity. "Protein binding" is uninformative for this specific anti-apoptotic
      binding
      activity.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "Protein binding" is too generic. The specific interaction is binding to pro-apoptotic
      Bax and Bcl-X(S) to sequester them and prevent apoptosis. This is better captured
      by
      the negative regulation of apoptotic process annotation (GO:0043066) already
      present.
      No single MF term perfectly captures anti-apoptotic binding, but the IPI evidence
      supports the GO:0043066 BP annotation.
    supported_by:
    - reference_id: PMID:14752512
      supporting_text: >-
        Using GST pulldown assays and coimmunoprecipitations, we demonstrated that
        alpha-crystallins bind to Bax and Bcl-X(S) both in vitro and in vivo
    - reference_id: PMID:14752512
      supporting_text: >-
        Through the interaction, alpha-crystallins prevent the translocation of Bax
        and
        Bcl-X(S) from cytosol into mitochondria during staurosporine-induced apoptosis
- term:
    id: GO:0042026
    label: protein refolding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  negated: true
  review:
    summary: >-
      NOT annotation for protein refolding (ISS from bovine ortholog via GO_REF:0000024).
      This
      is a critical annotation that explicitly states CRYAA does NOT perform protein
      refolding.
      CRYAA is a holdase chaperone that prevents aggregation of denatured proteins
      but does not
      actively refold them. This is consistent with all experimental evidence: PMID:8943244
      describes the chaperone-like activity as "the ability to suppress nonspecific
      aggregation"
      with no mention of refolding capability. The negated GOA assertion is
      therefore consistent with CRYAA being a holdase without foldase activity.
      This NOT annotation should be retained because it records the biologically
      important distinction between CRYAA holdase activity and active protein
      refolding.
    action: KEEP_AS_NON_CORE
    reason: >-
      The negated annotation correctly states that CRYAA does not perform active
      protein refolding. Retaining this NOT assertion is useful because it prevents
      propagation of a foldase interpretation and supports the replacement of
      unfolded protein binding with GO:0140309 "unfolded protein carrier activity."
    supported_by:
    - reference_id: PMID:8943244
      supporting_text: >-
        alpha-crystallin subunits associate to form large oligomeric aggregates that
        express
        chaperone-like activity, as defined by the ability to suppress nonspecific
        aggregation
        of proteins destabilized by treatment with a variety of denaturants
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IPI
  original_reference_id: PMID:8943244
  review:
    summary: >-
      GO:0051082 "unfolded protein binding" is being obsoleted (go-ontology#30962).
      This IPI annotation
      is based on PMID:8943244, which demonstrated that recombinant human alphaA-crystallin
      (CRYAA)
      suppresses heat-induced aggregation of aldose reductase (UniProtKB:P07320, the
      WITH/FROM
      interactor) and singlet-oxygen-induced aggregation of gamma-crystallin in stoichiometric
      amounts.
      The paper explicitly defines this as "chaperone-like activity" meaning the ability
      to suppress
      nonspecific aggregation of destabilized proteins. The C-terminal truncation
      mutant (R157STOP)
      showed markedly reduced chaperone-like activity despite preserved secondary
      structure, confirming
      that the C-terminal region is essential for the holdase function. The experimental
      evidence
      clearly supports that CRYAA binds partially denatured proteins and prevents
      their aggregation,
      which is holdase (not foldase) activity. The term GO:0140309 "unfolded protein
      holdase activity" is the appropriate MF replacement because CRYAA prevents
      aggregation without active refolding.
    action: MODIFY
    reason: >-
      GO:0051082 is being obsoleted. The experimental evidence from PMID:8943244 clearly
      demonstrates
      holdase chaperone activity -- CRYAA suppresses aggregation of heat-denatured
      aldose reductase
      and singlet-oxygen-damaged gamma-crystallin. This is not "unfolded protein binding"
      in a passive
      sense; it is active suppression of aggregation. The IPI evidence (with aldose
      reductase
      UniProtKB:P07320 as interactor) is strong. GO:0140309 "unfolded protein
      holdase activity" is the correct current MF term since CRYAA does NOT refold
      proteins. GO:0050821 "protein stabilization" is also relevant as a BP term.
    proposed_replacement_terms:
    - id: GO:0140309
      label: unfolded protein carrier activity
    additional_reference_ids:
    - PMID:18407550
    supported_by:
    - reference_id: PMID:8943244
      supporting_text: >-
        alpha-crystallin subunits associate to form large oligomeric aggregates that
        express
        chaperone-like activity, as defined by the ability to suppress nonspecific
        aggregation of
        proteins destabilized by treatment with a variety of denaturants including
        heat, UV
        irradiation, and chemical modification
    - reference_id: PMID:8943244
      supporting_text: >-
        When added in stoichiometric amounts, both WT and W9F subunits completely
        suppressed the
        heat-induced aggregation of aldose reductase
    - reference_id: PMID:8943244
      supporting_text: >-
        subunits encoded by a truncation mutant in which the C-terminal 17 residues
        were deleted
        (R157STOP), despite having spectroscopic properties similar to WT, formed
        much larger
        aggregates with a marked reduction in chaperone-like activity
- term:
    id: GO:0007601
    label: visual perception
  evidence_type: IMP
  original_reference_id: PMID:9467006
  review:
    summary: >-
      IMP annotation for visual perception from PMID:9467006. This study identified
      the R116C
      missense mutation in CRYAA as causing autosomal dominant congenital cataract
      (ADCC) in
      a family. The logic is that mutation in CRYAA causes cataract, which impairs
      visual
      perception. However, CRYAA does not directly participate in phototransduction
      or visual
      signaling. It maintains lens transparency, which is a prerequisite for vision
      but not
      part of the perception pathway itself. The IMP evidence connects CRYAA to visual
      impairment
      through lens opacity, not through a direct role in visual perception.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      While CRYAA mutations cause cataracts that impair vision (PMID:9467006), CRYAA
      does not
      participate in the visual perception signaling pathway. It maintains lens structural
      integrity. GO:0002088 "lens development in camera-type eye" and GO:0005212 "structural
      constituent of eye lens" better capture the role. Marking as over-annotated
      because the
      connection to visual perception is indirect.
    supported_by:
    - reference_id: PMID:9467006
      supporting_text: >-
        we found that a missense mutation, R116C, is associated with ADCC in this
        family
- term:
    id: GO:0043066
    label: negative regulation of apoptotic process
  evidence_type: IMP
  original_reference_id: PMID:14512969
  review:
    summary: >-
      IMP annotation for negative regulation of apoptotic process from PMID:14512969.
      This study
      identified the R49C mutation in CRYAA and showed that the R49C mutant protein
      failed to
      protect lens epithelial cells from staurosporine-induced apoptotic cell death,
      whereas
      wild-type CRYAA did protect. The IMP logic is that loss-of-function mutation
      leads to
      failure to suppress apoptosis, implicating wild-type CRYAA in negative regulation
      of
      apoptosis. This is well-supported anti-apoptotic activity, consistent with the
      IBA and IDA
      annotations to the same term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Anti-apoptotic function is well demonstrated by mutant phenotype: the R49C mutant
      fails
      to protect from staurosporine-induced apoptosis (PMID:14512969). This is a secondary
      function compared to the core structural and chaperone holdase roles.
    supported_by:
    - reference_id: PMID:14512969
      supporting_text: >-
        unlike wild-type CRYAA, the R49C mutant protein was abnormally localized to
        the nucleus
        and failed to protect from staurosporine-induced apoptotic cell death
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IMP
  original_reference_id: PMID:18407550
  review:
    summary: >-
      GO:0051082 "unfolded protein binding" is being obsoleted (go-ontology#30962).
      This IMP annotation
      is based on PMID:18407550, which identified the R116H (c.346G>A) mutation in
      CRYAA as the cause
      of autosomal dominant congenital cataract in a large Chinese family. The mutant
      phenotype evidence
      is that the R116H mutant protein showed loss of chaperone activity in the DTT-induced
      insulin
      aggregation assay, increased hydrophobicity, and increased binding affinity
      to lysozyme. The
      logic is: mutation in CRYAA causes loss of chaperone (holdase) activity, leading
      to cataract,
      therefore wild-type CRYAA enables this chaperone function. This is valid IMP
      evidence for
      chaperone holdase activity. However, the term "unfolded protein binding" does
      not accurately
      capture the functional consequence measured, which is suppression of protein
      aggregation (holdase
      activity). GO:0140309 "unfolded protein carrier activity" is the appropriate
      replacement.
    action: MODIFY
    reason: >-
      GO:0051082 is being obsoleted. The IMP evidence from PMID:18407550 is based
      on the R116H
      cataract-causing mutation showing loss of chaperone activity in DTT-induced
      insulin aggregation
      assay. This demonstrates the functional importance of CRYAA holdase activity
      but the term
      "unfolded protein binding" mischaracterizes the function. GO:0140309
      "unfolded protein carrier activity" is the correct replacement because the
      evidence shows CRYAA prevents aggregation rather than assisting folding.
    proposed_replacement_terms:
    - id: GO:0140309
      label: unfolded protein carrier activity
    additional_reference_ids:
    - PMID:8943244
    supported_by:
    - reference_id: PMID:18407550
      supporting_text: >-
        loss of chaperone activity of the mutant was seen in DTT (DL-dithiothreitol)-induced
        insulin
        aggregation assay
    - reference_id: PMID:18407550
      supporting_text: >-
        Gain of activated lysozyme binding, elevation of hydrophobicity and loss of
        chaperone
        activity of the mutant protein may be some of the molecular mechanisms underlying
        cataract
        in this large family
    - reference_id: PMID:18407550
      supporting_text: >-
        Sequencing of CRYAA revealed a novel heterozygous G>A transition (c.346G>A)
        in exon 3 that
        cosegregated with the disease phenotype and results in a conservative substitution
        of Arg
        to His at codon 116 (p.R116H)
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:14752512
  review:
    summary: >-
      IDA annotation for cytoplasm from PMID:14752512. This study demonstrated that
      alphaA-
      and alphaB-crystallins reside in the cytosol and prevent the translocation of
      pro-apoptotic
      Bax and Bcl-X(S) from cytosol to mitochondria during staurosporine-induced apoptosis.
      The abstract states that "alpha-crystallins prevent the translocation of Bax
      and Bcl-X(S)
      from cytosol into mitochondria during staurosporine-induced apoptosis" (PMID:14752512),
      implying CRYAA co-localizes with these targets in the cytoplasm. This is consistent
      with
      multiple other IDA studies confirming cytoplasmic localization (PMID:29259299,
      PMID:19464326,
      PMID:19503744, PMID:26004348, PMID:30340470).
    action: ACCEPT
    reason: >-
      Cytoplasmic localization is the primary constitutive location of CRYAA. PMID:14752512
      demonstrates CRYAA in the cytosol where it interacts with and sequesters Bax
      and Bcl-X(S).
      This is consistent with all other localization studies and represents a core
      annotation.
    supported_by:
    - reference_id: PMID:14752512
      supporting_text: >-
        alpha-crystallins prevent the translocation of Bax and Bcl-X(S) from cytosol
        into
        mitochondria during staurosporine-induced apoptosis
- term:
    id: GO:0032387
    label: negative regulation of intracellular transport
  evidence_type: IDA
  original_reference_id: PMID:14752512
  review:
    summary: >-
      IDA annotation for negative regulation of intracellular transport from PMID:14752512.
      This study demonstrated using GST pulldown assays and coimmunoprecipitation
      that alphaA-
      and alphaB-crystallins bind to pro-apoptotic Bax and Bcl-X(S) both in vitro
      and in vivo,
      and "prevent the translocation of Bax and Bcl-X(S) from cytosol into mitochondria
      during
      staurosporine-induced apoptosis" (PMID:14752512). This is a specific form of
      negative
      regulation of intracellular transport -- CRYAA sequesters these proteins in
      the cytosol,
      preventing their mitochondrial translocation. The cataract-causing R116C mutant
      shows
      "much weaker affinity to Bax and Bcl-X(S)" (PMID:14752512), further supporting
      that
      wild-type CRYAA actively prevents this transport. This is a secondary, non-core
      function
      tied to the anti-apoptotic role rather than the primary structural or chaperone
      holdase
      functions.
    action: KEEP_AS_NON_CORE
    reason: >-
      The annotation is well supported by direct experimental evidence from PMID:14752512
      showing that CRYAA prevents translocation of Bax and Bcl-X(S) from cytosol to
      mitochondria. However, this is a secondary function tied to the anti-apoptotic
      role,
      not the core structural or chaperone holdase activity of CRYAA. Marked as non-core
      for consistency with the anti-apoptotic annotations (GO:0043066).
    supported_by:
    - reference_id: PMID:14752512
      supporting_text: >-
        Through the interaction, alpha-crystallins prevent the translocation of Bax
        and
        Bcl-X(S) from cytosol into mitochondria during staurosporine-induced apoptosis
    - reference_id: PMID:14752512
      supporting_text: >-
        Two prominent mutants, R116C in alphaA-crystallin and R120G, in alphaB-crystallin
        display much weaker affinity to Bax and Bcl-X(S)
- term:
    id: GO:0043066
    label: negative regulation of apoptotic process
  evidence_type: IDA
  original_reference_id: PMID:14752512
  review:
    summary: >-
      IDA annotation for negative regulation of apoptotic process from PMID:14752512.
      This
      study directly demonstrated that "Human alphaA- and alphaB-crystallins prevent
      staurosporine-induced apoptosis through interactions with members of the Bcl-2
      family"
      (PMID:14752512). Using GST pulldown and coimmunoprecipitation, the authors showed
      that
      alpha-crystallins bind to pro-apoptotic Bax and Bcl-X(S) both in vitro and in
      vivo,
      sequestering them in the cytosol and preventing their translocation to mitochondria.
      As a result, "alpha-crystallins preserve the integrity of mitochondria, restrict
      release
      of cytochrome c, repress activation of caspase-3 and block degradation of PARP"
      (PMID:14752512). The anti-apoptotic function was confirmed in human lens epithelial
      cells,
      ARPE-19 cells, and H9c2 cells under staurosporine, etoposide, or sorbitol treatment.
      The R116C cataract mutant showed much weaker affinity to Bax and Bcl-X(S), consistent
      with loss of anti-apoptotic activity contributing to cataract pathology. This
      is a well-
      documented secondary function of CRYAA beyond its primary structural and chaperone
      roles.
    action: KEEP_AS_NON_CORE
    reason: >-
      Anti-apoptotic activity of CRYAA is directly demonstrated by IDA evidence in
      PMID:14752512 using multiple experimental approaches (GST pulldown, coimmunoprecipitation,
      functional apoptosis assays in multiple cell types). However, this is a secondary
      function
      compared to the core structural lens protein and chaperone holdase roles. Marked
      as
      non-core for consistency with the IBA and IMP annotations for the same GO term.
    supported_by:
    - reference_id: PMID:14752512
      supporting_text: >-
        Human alphaA- and alphaB-crystallins prevent staurosporine-induced apoptosis
        through
        interactions with members of the Bcl-2 family
    - reference_id: PMID:14752512
      supporting_text: >-
        Using GST pulldown assays and coimmunoprecipitations, we demonstrated that
        alpha-crystallins bind to Bax and Bcl-X(S) both in vitro and in vivo
    - reference_id: PMID:14752512
      supporting_text: >-
        alpha-crystallins preserve the integrity of mitochondria, restrict release
        of
        cytochrome c, repress activation of caspase-3 and block degradation of PARP
- term:
    id: GO:0007601
    label: visual perception
  evidence_type: IMP
  original_reference_id: PMID:14512969
  review:
    summary: >-
      IMP annotation for visual perception from PMID:14512969. This study identified
      the R49C
      missense mutation in CRYAA as causing autosomal dominant "nuclear" cataract
      in a four-
      generation family. The mutant protein "was abnormally localized to the nucleus
      and failed
      to protect from staurosporine-induced apoptotic cell death" (PMID:14512969).
      The logic
      connecting CRYAA to visual perception is that the R49C mutation causes cataract
      (lens
      opacity), which impairs vision. However, CRYAA does not directly participate
      in the visual
      perception signaling pathway (phototransduction). It maintains lens structural
      integrity
      and transparency, which is a prerequisite for light transmission but not part
      of the
      perception process itself. GO:0002088 "lens development in camera-type eye"
      and GO:0005212
      "structural constituent of eye lens" more accurately capture the actual role.
      This is the
      same over-annotation issue identified for the IEA (GO_REF:0000043) and IMP (PMID:9467006)
      visual perception annotations already reviewed.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      While the R49C CRYAA mutation causes autosomal dominant cataract that impairs
      vision
      (PMID:14512969), CRYAA does not participate in the visual perception signaling
      pathway.
      It maintains lens transparency through its structural and chaperone roles. The
      connection
      to visual perception is indirect -- through lens opacity rather than involvement
      in
      phototransduction. GO:0002088 "lens development in camera-type eye" and GO:0005212
      "structural constituent of eye lens" better capture the actual function. Consistent
      with the assessment of the other visual perception annotations for CRYAA.
    supported_by:
    - reference_id: PMID:14512969
      supporting_text: >-
        unlike wild-type CRYAA, the R49C mutant protein was abnormally localized to
        the
        nucleus and failed to protect from staurosporine-induced apoptotic cell death
    - reference_id: PMID:14512969
      supporting_text: >-
        Hereditary cataract is a clinically and genetically heterogeneous lens disease
        that
        accounts for a significant proportion of visual impairment and blindness in
        childhood
core_functions:
- molecular_function:
    id: GO:0140309
    label: unfolded protein carrier activity
  description: >-
    CRYAA (HSPB4) is a small heat shock protein that functions as an ATP-independent
    holdase chaperone. It forms large homo-oligomeric complexes (~540 kDa, ~24 subunits)
    that suppress nonspecific aggregation of proteins destabilized by heat, UV irradiation,
    and chemical modification. CRYAA does NOT actively refold substrates (documented
    by
    NOT annotation to GO:0042026 protein refolding). It maintains denatured proteins
    in a
    soluble, non-aggregated state. The C-terminal extension is essential for chaperone
    activity, and the T148 phosphorylation site (mediated by mTORC2) regulates chaperone
    capacity. Disease-causing mutations (R116C, R116H, R49C, F71L) impair chaperone
    holdase activity and cause congenital cataracts.
  directly_involved_in:
  - id: GO:0050821
    label: protein stabilization
  - id: GO:0009408
    label: response to heat
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:8943244
    supporting_text: >-
      alpha-crystallin subunits associate to form large oligomeric aggregates that
      express chaperone-like activity, as defined by the ability to suppress nonspecific
      aggregation of proteins destabilized by treatment with a variety of denaturants
      including heat, UV irradiation, and chemical modification.
  - reference_id: PMID:12235146
    supporting_text: >-
      the chimeric alphaB with the C-terminal extension of alphaA-crystallin exhibits
      dramatically enhanced chaperone-like activity.
    full_text_unavailable: true
  - reference_id: PMID:18407550
    supporting_text: >-
      loss of chaperone activity of the mutant was seen in DTT-induced insulin
      aggregation assay.
    full_text_unavailable: true
- molecular_function:
    id: GO:0005212
    label: structural constituent of eye lens
  description: >-
    CRYAA is the most abundantly expressed protein in the ocular lens, contributing
    to
    lens transparency and refractive index. It serves a dual role as a structural
    protein
    providing the high-concentration protein matrix required for lens transparency,
    and
    as a chaperone preventing aggregation of damaged crystallins that would cause
    light-scattering opacification. CRYAA hetero-oligomerizes with CRYAB (HSPB5) in
    a
    3:1 ratio. Mutations in CRYAA consistently cause autosomal dominant congenital
    cataracts (ADCC), confirming its essential structural role.
  directly_involved_in:
  - id: GO:0002088
    label: lens development in camera-type eye
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:14512969
    supporting_text: >-
      The alphaA-crystallin (CRYAA) gene (CRYAA) encodes a member of the small-heat-shock
      protein (sHSP) family of molecular chaperones and is primarily and abundantly
      expressed in the ocular lens
  - reference_id: PMID:9467006
    supporting_text: >-
      we found that a missense mutation, R116C, is associated with ADCC in this family.
  - reference_id: PMID:16303126
    supporting_text: >-
      the major lenticular protein chaperones, alpha A- and alpha B-crystallin,
      increased the solubility of the T5P gamma C-crystallin both in vitro and in
      transfected cells.
references:
- id: UniProtKB:P02489
  title: UniProtKB entry for human CRYAA (Alpha-crystallin A chain)
  findings:
    - statement: >-
        UniProt records CRYAA as cytoplasmic and stress-induced nuclear, with
        heat-shock-dependent residence in SC35/nuclear splicing speckles.
      supporting_text: >-
        Nucleus. Note=Translocates to the nucleus during heat shock and resides
        in sub-nuclear structures known as SC35 speckles or nuclear splicing
        speckles.
- 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:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  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:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning 
    models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:11700327
  title: Detection of protein-protein interactions among lens crystallins in a 
    mammalian two-hybrid system assay.
  findings: []
- id: PMID:12235146
  title: Role of the C-terminal extensions of alpha-crystallins. Swapping the 
    C-terminal extension of alpha-crystallin to alphaB-crystallin results in 
    enhanced chaperone activity.
  findings: []
- id: PMID:12601044
  title: Alteration of protein-protein interactions of congenital cataract 
    crystallin mutants.
  findings: []
- id: PMID:14512969
  title: Cell death triggered by a novel mutation in the alphaA-crystallin gene 
    underlies autosomal dominant cataract linked to chromosome 21q.
  findings: []
- id: PMID:14752512
  title: Human alphaA- and alphaB-crystallins bind to Bax and Bcl-X(S) to 
    sequester their translocation during staurosporine-induced apoptosis.
  findings: []
- id: PMID:16303126
  title: Lenticular chaperones suppress the aggregation of the cataract-causing 
    mutant T5P gamma C-crystallin.
  findings: []
- id: PMID:18407550
  title: A novel mutation in AlphaA-crystallin (CRYAA) caused autosomal dominant
    congenital cataract in a large Chinese family.
  findings: []
- id: PMID:19464326
  title: HSPB7 is a SC35 speckle resident small heat shock protein.
  findings: []
- id: PMID:19503744
  title: An alphaA-crystallin gene mutation, Arg12Cys, causing inherited 
    cataract-microcornea exhibits an altered heat-shock response.
  findings: []
- id: PMID:19651604
  title: The eye lens chaperone alpha-crystallin forms defined globular 
    assemblies.
  findings: []
- id: PMID:22085609
  title: 'Temperature-dependent structural and functional properties of a mutant (F71L)
    αA-crystallin: molecular basis for early onset of age-related cataract.'
  findings: []
- id: PMID:22153508
  title: The polydispersity of αB-crystallin is rationalized by an 
    interconverting polyhedral architecture.
  findings: []
- id: PMID:23188086
  title: 'Binding determinants of the small heat shock protein, αB-crystallin: recognition
    of the ''IxI'' motif.'
  findings: []
- id: PMID:25416956
  title: A proteome-scale map of the human interactome network.
  findings: []
- id: PMID:25910212
  title: Widespread macromolecular interaction perturbations in human genetic 
    disorders.
  findings: []
- id: PMID:26004348
  title: Mutation analysis of two families with inherited congenital cataracts.
  findings: []
- id: PMID:29259299
  title: Two novel mutations identified in ADCC families impair crystallin 
    protein distribution and induce apoptosis in human lens epithelial cells.
  findings: []
- id: PMID:29892012
  title: An interactome perturbation framework prioritizes damaging missense 
    mutations for developmental disorders.
  findings: []
- id: PMID:30340470
  title: A novel mutation in the CRYAA gene associated with congenital cataract 
    and microphthalmia in a Chinese family.
  findings: []
- id: PMID:31515488
  title: Extensive disruption of protein interactions by genetic variants across
    the allele frequency spectrum in human populations.
  findings: []
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
- id: PMID:32814053
  title: Interactome Mapping Provides a Network of Neurodegenerative Disease 
    Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.
  findings: []
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the 
    human interactome.
  findings: []
- id: PMID:8943244
  title: Cloning, expression, and chaperone-like activity of human 
    alphaA-crystallin.
  findings: []
- id: PMID:9467006
  title: Autosomal dominant congenital cataract associated with a missense 
    mutation in the human alpha crystallin gene CRYAA.
  findings: []
- id: file:human/CRYAA/CRYAA-deep-research-falcon.md
  title: Falcon deep research for human CRYAA
  findings:
    - statement: >-
        Falcon synthesis supports CRYAA/HSPB4 as an alpha-crystallin small heat
        shock protein with ATP-independent holdase chaperone activity central to
        lens proteostasis and cataract biology.