DNAJC4

UniProt ID: Q9NNZ3
Organism: Homo sapiens
Review Status: COMPLETE
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Gene Description

DNAJC4 (DnaJ homolog subfamily C member 4; also called DnaJ-like protein HSPF2 and MEN1 candidate protein 18, MCG18) is a poorly characterized member of the DnaJ/HSP40 (type III, "C") co-chaperone family. It comprises an N-terminal J domain (the signature HPD-motif-containing module that engages and stimulates HSP70 chaperones), a disordered central region, and a predicted single-pass transmembrane helix near the C-terminus, consistent with annotation as a membrane protein. By family assignment it is expected to act as an HSP70 co-chaperone, but no direct biochemical characterization of its chaperone activity or client repertoire has been reported. It is expressed broadly with enhancement in testis.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0016020 membrane
IEA
GO_REF:0000120 		ACCEPT
Summary: Electronic annotation of membrane localization, consistent with the UniProt single-pass transmembrane prediction.
Reason: A predicted helical transmembrane segment (residues 156-175) and UniProt annotation as a single-pass membrane protein support membrane localization; this is the best-supported compartment for DNAJC4.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
SUBCELLULAR LOCATION: Membrane
GO:0005515 protein binding
IPI
PMID:17500595
Huntingtin interacting proteins are genetic modifiers of neu... 		KEEP AS NON CORE
Summary: IntAct capture of a DNAJC4-HTT (huntingtin) interaction from a huntingtin-interactor screen. The bare protein binding term is uninformative and the partner does not define a chaperone function for DNAJC4.
Reason: Records a real but uninformative high-throughput interaction with huntingtin; per curation guidelines, bare protein binding is not elevated to core and there is no specific informative MF that this single interaction establishes for DNAJC4.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
Q9NNZ3; P42858: HTT; NbExp=12
GO:0005515 protein binding
IPI
PMID:32814053
Interactome Mapping Provides a Network of Neurodegenerative ... 		KEEP AS NON CORE
Summary: Neurodegeneration-focused interactome screen capturing a DNAJC4-WFS1 (wolframin) interaction. Bare protein binding is uninformative.
Reason: Records a real high-throughput interaction (with WFS1) but is uninformative as a molecular function; not elevated to core.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
Q9NNZ3; O76024: WFS1; NbExp=3
GO:0006986 response to unfolded protein
TAS
PMID:9473517
Characterisation of a new human and murine member of the Dna... 		KEEP AS NON CORE
Summary: Process annotation derived from the original cloning paper, reflecting the family-level expectation that a DnaJ protein participates in the unfolded-protein/stress response rather than a demonstrated role for DNAJC4 specifically.
Reason: Plausible family-level inference from the DnaJ/HSP40 assignment but not experimentally demonstrated for DNAJC4; retained as a non-core process.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
DnaJ-like protein HSPF2
GO:0016020 membrane
TAS
PMID:9473517
Characterisation of a new human and murine member of the Dna... 		ACCEPT
Summary: Curated (TAS) membrane localization from the cloning paper, redundant with and consistent with the IEA membrane annotation and the predicted transmembrane helix.
Reason: Agrees with the predicted single-pass transmembrane segment and UniProt membrane assignment.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
Single-pass membrane protein
GO:0006457 protein folding
NAS
PMID:9473517
Characterisation of a new human and murine member of the Dna... 		KEEP AS NON CORE
Summary: Non-traceable author statement that DNAJC4 participates in protein folding, a family-level inference for a DnaJ/HSP40 co-chaperone. DnaJ proteins are co-chaperones that assist HSP70 rather than autonomous foldases.
Reason: Protein folding is a downstream process outcome of the HSP70 system that J-domain co-chaperones assist; it is a plausible but non-core, inference-level annotation for this uncharacterized protein.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
DnaJ-like protein HSPF2
GO:0016020 membrane
NAS
PMID:9473517
Characterisation of a new human and murine member of the Dna... 		ACCEPT
Summary: Non-traceable author statement of membrane localization, redundant with the TAS and IEA membrane annotations.
Reason: Consistent with the predicted transmembrane helix and UniProt membrane assignment.
Supporting Evidence:
file:human/DNAJC4/DNAJC4-uniprot.txt
Single-pass membrane protein

Core Functions

Predicted HSP70 (DnaJ/HSP40) co-chaperone, defined by an N-terminal J domain that in characterized family members engages and stimulates HSP70 chaperones. No direct experimental characterization of DNAJC4's activity or clients exists, so this is a family-level molecular assignment rather than a verified function.

Molecular Function:
unfolded protein binding
Cellular Locations:
membrane
Supporting Evidence:
  • file:human/DNAJC4/DNAJC4-uniprot.txt
    DnaJ-like protein HSPF2

References

GO_REF:0000120
Combined Automated Annotation using Multiple IEA Methods
PMID:17500595
Huntingtin interacting proteins are genetic modifiers of neurodegeneration.
PMID:32814053
Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.
PMID:9473517
Characterisation of a new human and murine member of the DnaJ family of proteins.
  • DNAJC4/HSPF2 was identified as a new member of the DnaJ/HSP40 family; assignment to this family is the basis for its inferred protein-folding/unfolded-protein-response and membrane annotations.

Suggested Questions for Experts

Q: Does DNAJC4 function as a bona fide HSP70 co-chaperone (i.e. does its J domain stimulate HSP70 ATPase activity), and which HSP70 paralog does it partner with?

Q: What is the topology and subcellular destination of the predicted single-pass transmembrane DNAJC4, and does it act on a specific membrane compartment?

Suggested Experiments

Experiment: In vitro single-turnover and steady-state ATPase assays with purified DNAJC4 J domain plus HSPA8/HSPA1A to test whether DNAJC4 stimulates HSP70 ATPase activity, with a J-domain HPD-motif mutant as negative control.

Experiment: Tagged-DNAJC4 affinity purification-mass spectrometry from a relevant cell type to define its interactome and any specific client or HSP70 partner beyond the existing high-throughput hits.

📚 Additional Documentation

Notes

(DNAJC4-notes.md)

DNAJC4 (Q9NNZ3) research notes

Identity

  • DnaJ homolog subfamily C member 4; AltNames DnaJ-like protein HSPF2; MEN1 candidate protein 18 (MCG18).
  • 241 aa. Contains a J domain (aa 34-99) [file:human/DNAJC4/DNAJC4-uniprot.txt "DOMAIN 34..99 /note=\"J\""].
  • Has a predicted single-pass transmembrane helix (TRANSMEM 156..175) and is annotated as a membrane / single-pass membrane protein [file:human/DNAJC4/DNAJC4-uniprot.txt "SUBCELLULAR LOCATION: Membrane ... Single-pass membrane protein"].
  • Tissue: HPA "Tissue enhanced (testis)"; Pharos Tdark (very poorly characterized).
  • PAN-GO: 0 GO annotations based on evolutionary models (i.e. family-level functional inference is weak).

Function status

  • A J-domain protein, so by family it is an HSP70 (DnaJ/HSP40) co-chaperone, but there is essentially NO direct experimental characterization of its activity. UniProt does not even provide a FUNCTION comment.
  • The original cloning paper PMID:9473517 is the basis for the NAS protein-folding and TAS response-to-unfolded-protein / membrane annotations. These are family/inference-level, not demonstrated for DNAJC4 specifically.

Interactions (GOA / IntAct)

  • HTT (huntingtin, P42858); NbExp=12 [file:human/DNAJC4/DNAJC4-uniprot.txt "Q9NNZ3; P42858: HTT; NbExp=12"]. From Huntingtin-interactome screens (PMID:17500595 = Kaltenbach et al., HTT interactors).
  • WFS1 (wolframin, O76024); NbExp=3 [file:human/DNAJC4/DNAJC4-uniprot.txt "Q9NNZ3; O76024: WFS1; NbExp=3"]. From PMID:32814053 (neurodegeneration interactome).
  • These are high-throughput / focused interactome screens; "protein binding" (GO:0005515) is uninformative; partners (HTT, WFS1) do not define a chaperone client repertoire.

Curation judgment

  • Core MF: J-domain co-chaperone presumed to be an HSP70 ATPase activator, but NOT experimentally supported -> cannot assert ATPase activator as a verified core; the only experimentally-supportable molecular role is the J domain unfolded-protein-binding / Hsp70-cochaperone family assignment. Use unfolded protein binding (GO:0051082) cautiously (NAS family-level). Avoid overstating.
  • Membrane localization: predicted single-pass TM; reasonable to KEEP_AS_NON_CORE / ACCEPT as predicted.
  • protein binding IPI (HTT, WFS1): KEEP_AS_NON_CORE (records real interactions but uninformative; not core).
  • response to unfolded protein (TAS) and protein folding (NAS): family/inference-level; keep as non-core.

Pn Notes

(DNAJC4-pn-notes.md)

DNAJC4 PN Consistency Notes

  • Generated: 2026-06-18
  • Project: PROTEOSTASIS
  • Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
  • UniProt: Q9NNZ3
  • AIGR review status: COMPLETE
  • Review batch: proteostasis-batch-2026-06-07b
  • Batch change status: added

Source Files Checked

Deep Research Files

  • No *-deep-research*.md file found in this gene directory.

AIGR Review Snapshot

  • Description: DNAJC4 (DnaJ homolog subfamily C member 4; also called DnaJ-like protein HSPF2 and MEN1 candidate protein 18, MCG18) is a poorly characterized member of the DnaJ/HSP40 (type III, "C") co-chaperone family. It comprises an N-terminal J domain (the signature HPD-motif-containing module that engages and stimulates HSP70 chaperones), a disordered central region, and a predicted single-pass transmembrane helix near the C-terminus, consistent with annotation as a membrane protein. By family assignment it is expected to act as an HSP70 co-chaperone, but no direct biochemical characterization of its chaperone activity or client repertoire has been reported. It is expressed broadly with enhancement in testis.
  • Existing/core annotation action counts: ACCEPT: 3; KEEP_AS_NON_CORE: 4

PN Consistency Summary

  • Consistency: Mostly consistent but with a placement nuance and an MF mismatch. Deep research (notes), review and PN agree DNAJC4 is a Tdark, essentially uncharacterized type-III DnaJ/HSP40 co-chaperone (J domain aa 34-99) with a predicted single-pass TM helix; PAN-GO returns 0 evolutionary annotations. No experimental chaperone data exist. Discrepancy 1: PN places DNAJC4 in the Mitochondrial branch, but neither the review nor notes give any mitochondrial evidence (review's only locations are membrane/single-pass TM; UniProt gives no mito targeting). Discrepancy 2: PN projects GO:0030544 Hsp70 protein binding as the type MF, but the review's core MF is GO:0051082 unfolded protein binding (chosen deliberately as a cautious family-level call) — GO:0030544 appears nowhere in the review.
  • PN story / NEW pressure: PN asserts an Hsp70-binding MF (GO:0030544, verified real via OLS) not present in GOA (GOA has only response to unfolded protein, BP) nor in the review. For a J-domain protein this is the canonical co-chaperone MF and is defensible by family, but is unverified experimentally for DNAJC4 specifically — consistent with the review's deliberately cautious GO:0051082. Conclusion: a defensible family-level ADD candidate, but unverified; do not assert as core.
  • Evidence alignment: PN row carries no reference titles. Review/notes cite PMID:9473517 (cloning paper; UNVERIFIED, not cached), PMID:17500595 (HTT interactome), PMID:32814053 (neurodegeneration interactome). No overlap with PN, but no contradiction.
  • Verdict: Family-level J-co-chaperone call sound; GO:0030544 is a defensible-but-unverified ADD; mitochondrial placement and the GO:0030544-vs-GO:0051082 MF mismatch need reconciling. Recommended edits: [MAP] reconcile Hsp70 protein binding (GO:0030544) projection with the review's GO:0051082 unfolded protein binding — both are family-level/unverified; prefer GO:0030544 only if asserted as predicted, not experimental. [MAP][WB] verify the Mitochondrial-branch assignment — no mitochondrial localization evidence appears in the review or notes.

Full Consistency Review

  • UniProt: Q9NNZ3 · batch: proteostasis-batch-2026-06-07b · review status: COMPLETE
  • PN placement: Mitochondrial proteostasis|Chaperone|HSP70 system|J-domain containing HSP70 cochaperone (branch MI) ; PN-node mapping: type → mapped/ok_for_propagation_to_go GO:0030544 Hsp70 protein binding (goa_status=more_specific_than_existing_goa); all ancestor nodes no_mapping.
  • Consistency: Mostly consistent but with a placement nuance and an MF mismatch. Deep research (notes), review and PN agree DNAJC4 is a Tdark, essentially uncharacterized type-III DnaJ/HSP40 co-chaperone (J domain aa 34-99) with a predicted single-pass TM helix; PAN-GO returns 0 evolutionary annotations. No experimental chaperone data exist. Discrepancy 1: PN places DNAJC4 in the Mitochondrial branch, but neither the review nor notes give any mitochondrial evidence (review's only locations are membrane/single-pass TM; UniProt gives no mito targeting). Discrepancy 2: PN projects GO:0030544 Hsp70 protein binding as the type MF, but the review's core MF is GO:0051082 unfolded protein binding (chosen deliberately as a cautious family-level call) — GO:0030544 appears nowhere in the review.
  • PN story / NEW pressure: PN asserts an Hsp70-binding MF (GO:0030544, verified real via OLS) not present in GOA (GOA has only response to unfolded protein, BP) nor in the review. For a J-domain protein this is the canonical co-chaperone MF and is defensible by family, but is unverified experimentally for DNAJC4 specifically — consistent with the review's deliberately cautious GO:0051082. Conclusion: a defensible family-level ADD candidate, but unverified; do not assert as core.
  • Mapping strategy: Type-level GO:0030544 is appropriate breadth for a J-domain co-chaperone and is NOT an over-reach (unlike holdase claims). However the Mitochondrial-branch placement is unsupported by any evidence in the dossier and should be checked.
  • Evidence alignment: PN row carries no reference titles. Review/notes cite PMID:9473517 (cloning paper; UNVERIFIED, not cached), PMID:17500595 (HTT interactome), PMID:32814053 (neurodegeneration interactome). No overlap with PN, but no contradiction.
  • Verdict: Family-level J-co-chaperone call sound; GO:0030544 is a defensible-but-unverified ADD; mitochondrial placement and the GO:0030544-vs-GO:0051082 MF mismatch need reconciling. Recommended edits: [MAP] reconcile Hsp70 protein binding (GO:0030544) projection with the review's GO:0051082 unfolded protein binding — both are family-level/unverified; prefer GO:0030544 only if asserted as predicted, not experimental. [MAP][WB] verify the Mitochondrial-branch assignment — no mitochondrial localization evidence appears in the review or notes.

PN Dossier Context

  • review_batch: proteostasis-batch-2026-06-07b
  • review_yaml: genes/human/DNAJC4/DNAJC4-ai-review.yaml
  • PN workbook rows: 1

PN row 1: Mitochondrial proteostasis | Chaperone | HSP70 system | J-domain containing HSP70 cochaperone

  • UniProt: Q9NNZ3
  • In branches: MI
  • PN-node mapping records (path + ancestors):
    • [type] Mitochondrial proteostasis|Chaperone|HSP70 system|J-domain containing HSP70 cochaperone
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0030544 Hsp70 protein binding]
      rationale: In the PN hierarchy, this type denotes J-domain cochaperones assigned to the HSP70 system. Their shared mechanistic role is direct interaction with HSP70-family chaperones, making Hsp70 protein binding the most defensible GO target in the current cache.
    • [group] Mitochondrial proteostasis|Chaperone|HSP70 system
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a broad PN category rather than a specific GO class. The member genes span multiple activities, complexes, or contexts, so propagation from this node would overstate the shared biology; use narrower child or gene-level curations.
    • [class] Mitochondrial proteostasis|Chaperone
      status=no_mapping scope= GO=[]
      rationale: This PN class is too heterogeneous for a single safe GO mapping. In the workbook it mixes HSP70, HSP60, and HSP90 systems, small intermembrane-space chaperones, membrane-protein chaperones, and other mitochondrial-specific factors.
    • [branch] Mitochondrial proteostasis
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a top-level PN branch. This is a systems/taxonomy umbrella, not a direct GO assertion; narrower child curations carry any propagating GO mappings.

Projected GO annotations (1)

  • GO:0030544 Hsp70 protein binding | scope=ok_for_propagation_to_go | goa_status=more_specific_than_existing_goa | from=Mitochondrial proteostasis|Chaperone|HSP70 system|J-domain containing HSP70 cochaperone

Note

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

📄 View Raw YAML

 
id: Q9NNZ3
gene_symbol: DNAJC4
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: DNAJC4 (DnaJ homolog subfamily C member 4; also called DnaJ-like protein
  HSPF2 and MEN1 candidate protein 18, MCG18) is a poorly characterized member of
  the DnaJ/HSP40 (type III, "C") co-chaperone family. It comprises an N-terminal J
  domain (the signature HPD-motif-containing module that engages and stimulates HSP70
  chaperones), a disordered central region, and a predicted single-pass transmembrane
  helix near the C-terminus, consistent with annotation as a membrane protein. By
  family assignment it is expected to act as an HSP70 co-chaperone, but no direct biochemical
  characterization of its chaperone activity or client repertoire has been reported.
  It is expressed broadly with enhancement in testis.
existing_annotations:
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: Electronic annotation of membrane localization, consistent with the UniProt
      single-pass transmembrane prediction.
    action: ACCEPT
    reason: A predicted helical transmembrane segment (residues 156-175) and UniProt
      annotation as a single-pass membrane protein support membrane localization;
      this is the best-supported compartment for DNAJC4.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Membrane'
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17500595
  qualifier: enables
  review:
    summary: IntAct capture of a DNAJC4-HTT (huntingtin) interaction from a huntingtin-interactor
      screen. The bare protein binding term is uninformative and the partner does
      not define a chaperone function for DNAJC4.
    action: KEEP_AS_NON_CORE
    reason: Records a real but uninformative high-throughput interaction with huntingtin;
      per curation guidelines, bare protein binding is not elevated to core and there
      is no specific informative MF that this single interaction establishes for DNAJC4.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: 'Q9NNZ3; P42858: HTT; NbExp=12'
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  qualifier: enables
  review:
    summary: Neurodegeneration-focused interactome screen capturing a DNAJC4-WFS1
      (wolframin) interaction. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: Records a real high-throughput interaction (with WFS1) but is uninformative
      as a molecular function; not elevated to core.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: 'Q9NNZ3; O76024: WFS1; NbExp=3'
- term:
    id: GO:0006986
    label: response to unfolded protein
  evidence_type: TAS
  original_reference_id: PMID:9473517
  qualifier: involved_in
  review:
    summary: Process annotation derived from the original cloning paper, reflecting
      the family-level expectation that a DnaJ protein participates in the unfolded-protein/stress
      response rather than a demonstrated role for DNAJC4 specifically.
    action: KEEP_AS_NON_CORE
    reason: Plausible family-level inference from the DnaJ/HSP40 assignment but not
      experimentally demonstrated for DNAJC4; retained as a non-core process.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: DnaJ-like protein HSPF2
- term:
    id: GO:0016020
    label: membrane
  evidence_type: TAS
  original_reference_id: PMID:9473517
  qualifier: located_in
  review:
    summary: Curated (TAS) membrane localization from the cloning paper, redundant
      with and consistent with the IEA membrane annotation and the predicted transmembrane
      helix.
    action: ACCEPT
    reason: Agrees with the predicted single-pass transmembrane segment and UniProt
      membrane assignment.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: Single-pass membrane protein
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: NAS
  original_reference_id: PMID:9473517
  qualifier: involved_in
  review:
    summary: Non-traceable author statement that DNAJC4 participates in protein folding,
      a family-level inference for a DnaJ/HSP40 co-chaperone. DnaJ proteins are co-chaperones
      that assist HSP70 rather than autonomous foldases.
    action: KEEP_AS_NON_CORE
    reason: Protein folding is a downstream process outcome of the HSP70 system that
      J-domain co-chaperones assist; it is a plausible but non-core, inference-level
      annotation for this uncharacterized protein.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: DnaJ-like protein HSPF2
- term:
    id: GO:0016020
    label: membrane
  evidence_type: NAS
  original_reference_id: PMID:9473517
  qualifier: located_in
  review:
    summary: Non-traceable author statement of membrane localization, redundant with
      the TAS and IEA membrane annotations.
    action: ACCEPT
    reason: Consistent with the predicted transmembrane helix and UniProt membrane
      assignment.
    supported_by:
    - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
      supporting_text: Single-pass membrane protein
references:
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:17500595
  title: Huntingtin interacting proteins are genetic modifiers of neurodegeneration.
  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:9473517
  title: Characterisation of a new human and murine member of the DnaJ family of proteins.
  reference_review:
    relevance: HIGH
    correctness: UNVERIFIED
    review_notes: "Primary reference establishing DNAJC4/HSPF2 as a new DnaJ/HSP40
      family member; the family assignment underlies the inferred HSP70 co-chaperone
      molecular function and membrane localization. Not cached in publications/, so
      the identifier and supporting content could not be checked against a PubMed/
      cached anchor; title is consistent with the claim but left UNVERIFIED."
  findings:
  - statement: DNAJC4/HSPF2 was identified as a new member of the DnaJ/HSP40 family;
      assignment to this family is the basis for its inferred protein-folding/unfolded-protein-response
      and membrane annotations.
    reference_section_type: RESULTS
core_functions:
- description: Predicted HSP70 (DnaJ/HSP40) co-chaperone, defined by an N-terminal
    J domain that in characterized family members engages and stimulates HSP70 chaperones.
    No direct experimental characterization of DNAJC4's activity or clients exists,
    so this is a family-level molecular assignment rather than a verified function.
  molecular_function:
    id: GO:0051082
    label: unfolded protein binding
  locations:
  - id: GO:0016020
    label: membrane
  supported_by:
  - reference_id: file:human/DNAJC4/DNAJC4-uniprot.txt
    supporting_text: DnaJ-like protein HSPF2
proposed_new_terms: []
suggested_questions:
- question: Does DNAJC4 function as a bona fide HSP70 co-chaperone (i.e. does its J
    domain stimulate HSP70 ATPase activity), and which HSP70 paralog does it partner
    with?
- question: What is the topology and subcellular destination of the predicted single-pass
    transmembrane DNAJC4, and does it act on a specific membrane compartment?
suggested_experiments:
- description: In vitro single-turnover and steady-state ATPase assays with purified
    DNAJC4 J domain plus HSPA8/HSPA1A to test whether DNAJC4 stimulates HSP70 ATPase
    activity, with a J-domain HPD-motif mutant as negative control.
- description: Tagged-DNAJC4 affinity purification-mass spectrometry from a relevant
    cell type to define its interactome and any specific client or HSP70 partner beyond
    the existing high-throughput hits.