id: Q8N7S2 gene_symbol: DNAJC5G product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:9606 label: Homo sapiens description: DNAJC5G (cysteine string protein-gamma, CSP-gamma) is a testis-specific, poorly characterized paralog of the synaptic co-chaperone CSPalpha/DNAJC5. It carries an N-terminal J domain characteristic of DnaJ/HSP40 co-chaperones, which in characterized family members recruits and stimulates the HSP70 chaperone HSC70/HSPA8, together with a cysteine-string region that is predicted to be palmitoylated and to anchor the protein to membranes. No direct biochemical characterization of CSP-gamma's activity or clients has been reported; its function is inferred from family membership to be HSP70 co-chaperone activity in a testis secretory/membrane context. alternative_products: - name: '1' id: Q8N7S2-1 - name: '2' id: Q8N7S2-2 sequence_note: VSP_056967, VSP_056968 existing_annotations: - term: id: GO:0005737 label: cytoplasm evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: located_in review: summary: Electronic cytoplasm annotation from ARBA, consistent with a J-domain co-chaperone that is membrane-anchored with a cytoplasmic-facing pool. action: KEEP_AS_NON_CORE reason: Generic cytoplasm localization; plausible for a CSP-family co-chaperone but not experimentally established for CSP-gamma and less informative than the membrane lipid-anchor. supported_by: - reference_id: file:human/DNAJC5G/DNAJC5G-uniprot.txt supporting_text: Cysteine string protein-gamma - term: id: GO:0016020 label: membrane evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: Membrane localization from UniProt subcellular-location mapping; CSP-gamma is annotated as a lipid-anchored membrane protein by similarity to other cysteine string proteins. The falcon deep-research synthesis reaches the same family-level inference (palmitoylation-dependent membrane anchoring), and additionally notes DNAJC5G-specific proteomic detection in human sperm with a ring-shaped headpiece antibody-staining pattern, consistent with association with a membrane-bounded germ-cell compartment. action: ACCEPT reason: Consistent with the predicted palmitoylated cysteine-string membrane anchor shared across the CSP family; membrane is the best-supported compartment. The gene-specific sperm staining (ring-shaped headpiece) is consistent with, though does not pinpoint, a membrane-associated localization. supported_by: - reference_id: file:human/DNAJC5G/DNAJC5G-uniprot.txt supporting_text: 'SUBCELLULAR LOCATION: Membrane' - reference_id: file:human/DNAJC5G/DNAJC5G-deep-research-falcon.md supporting_text: ring-shaped in the headpiece references: - id: GO_REF:0000044 title: Gene Ontology annotation through association of InterPro records with GO terms findings: [] - id: GO_REF:0000117 title: Electronic Gene Ontology annotations created by ARBA machine learning models findings: [] - id: file:human/DNAJC5G/DNAJC5G-uniprot.txt title: UniProt entry Q8N7S2 (DNJ5G_HUMAN), cysteine string protein-gamma findings: - statement: Testis-specific CSP paralog with a J domain (aa 17-98) and a cysteine-string region; annotated as a membrane lipid-anchor and palmitoylated by similarity; no direct functional characterization (evidence at transcript level). reference_section_type: OTHER - id: file:human/DNAJC5G/DNAJC5G-deep-research-falcon.md title: Falcon deep research report for DNAJC5G findings: - statement: 'Safe, paralog-shared / family-level inferences usable for DNAJC5G: presence of a J domain implies an HSP70 co-chaperone (regulatory, non-catalytic) role; the cysteine-string region is expected to undergo S-palmitoylation and mediate membrane anchoring. Gene-specific experimental observations: DNAJC5G protein detected in human sperm by targeted MS/antibody methods, with testis-enriched expression and a ring-shaped headpiece staining pattern.' reference_section_type: OTHER reference_review: relevance: MEDIUM correctness: UNVERIFIED review_notes: 'LLM deep-research synthesis (no contexts retrieved per its own header; "this answer is not grounded in evidence but is instead a direct response from the agent model"), so all claims are UNVERIFIED pending primary-source checking. SAFE to use for DNAJC5G: J-domain HSP70 co-chaperone family inference and palmitoylated cysteine-string membrane anchoring (both family-level), plus the gene-specific testis/sperm detection and ring-shaped headpiece staining (attributed to Carapito et al. 2017 / Duek et al. 2016 proteomics, not yet independently verified here). MUST NOT be propagated to DNAJC5G: the report itself flags that CSP-alpha/DNAJC5-specific functions (synaptic vesicle co-chaperone, SNARE/SNAP-25 client handling, neuroprotection, ANCL disease) "should not be overextended to DNAJC5G" - these remain CSP-alpha-specific and are not evidenced for CSP-gamma.' core_functions: - description: Predicted HSP70 (DnaJ/HSP40) co-chaperone, defined by an N-terminal J domain that in characterized cysteine string proteins engages and stimulates HSC70/HSP70. No experimental characterization of CSP-gamma'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/DNAJC5G/DNAJC5G-uniprot.txt supporting_text: Cysteine string protein-gamma proposed_new_terms: [] suggested_questions: - question: Does CSP-gamma function as an HSC70/HSP70 co-chaperone (J-domain-dependent ATPase stimulation), and what is its testis-specific physiological role? - question: Is CSP-gamma palmitoylated and membrane-anchored in vivo as predicted, and to which membrane compartment is it targeted in germ cells? suggested_experiments: - description: In vitro HSC70 ATPase assays with purified CSP-gamma (wild-type and J-domain HPD-motif mutant) to test for co-chaperone activity. - description: Tagged-CSP-gamma expression and affinity purification-mass spectrometry from a testis-derived line to determine subcellular localization and identify interaction partners/clients.