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.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: Electronic cytoplasm annotation from ARBA, consistent with a J-domain co-chaperone that is membrane-anchored with a cytoplasmic-facing pool. 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. Supporting Evidence: file:human/DNAJC5G/DNAJC5G-uniprot.txt Cysteine string protein-gamma |
| GO:0016020 membrane | IEA GO_REF:0000044 | ACCEPT | 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. 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. Supporting Evidence: file:human/DNAJC5G/DNAJC5G-uniprot.txt SUBCELLULAR LOCATION: Membrane file:human/DNAJC5G/DNAJC5G-deep-research-falcon.md ring-shaped in the headpiece |
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Download this section (compressed HTML)Q: Does CSP-gamma function as an HSC70/HSP70 co-chaperone (J-domain-dependent ATPase stimulation), and what is its testis-specific physiological role?
Q: Is CSP-gamma palmitoylated and membrane-anchored in vivo as predicted, and to which membrane compartment is it targeted in germ cells?
Experiment: In vitro HSC70 ATPase assays with purified CSP-gamma (wild-type and J-domain HPD-motif mutant) to test for co-chaperone activity.
Experiment: Tagged-CSP-gamma expression and affinity purification-mass spectrometry from a testis-derived line to determine subcellular localization and identify interaction partners/clients.
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