ER-lumenal J-domain containing co-chaperone (DnaJ/Hsp40 family) in Candida albicans. CaJem1p is the ortholog of S. cerevisiae Jem1p and localizes to the endoplasmic reticulum. Functions together with BiP/Kar2p (ER Hsp70) in protein folding and quality control in the ER lumen. When expressed in S. cerevisiae, CaJem1p suppresses the temperature-sensitive growth and ER quality control defects of the jem1-delta scj1-delta mutant, confirming functional conservation (PMID:18754794). CaJem1p can also suppress the karyogamy defect of the jem1-delta mutant when overexpressed, though less efficiently than ScJem1p due to differences in the N-terminal domain that mediates interaction with Nep98p (PMID:18754794). Contains a DnaJ/J-domain (Pfam PF00226) and a TPR-like domain. Has a signal peptide for ER targeting.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0051087 protein-folding chaperone binding | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for binding to chaperone proteins. JEM1 is a J-domain co-chaperone that binds to and stimulates the ATPase activity of the ER Hsp70 BiP/Kar2p. Reason: JEM1/Jem1p functions as a co-chaperone partner for the ER Hsp70 BiP/Kar2p. PMID:18754794 states that Jem1p "functions together with another J protein, Scj1p, in protein folding and quality control in the ER as a partner for the ER Hsp70 (BiP/Kar2p)." Binding to a protein-folding chaperone (BiP) is a core function. Supporting Evidence: PMID:18754794 Jem1p is required for nuclear fusion during mating (karyogamy) and functions together with another J protein, Scj1p, in protein folding and quality control in the ER as a partner for the ER Hsp70 (BiP/Kar2p). file:CANAL/JEM1/JEM1-deep-research-falcon.md Biochemical pull-down evidence shows CaJem1p binds BiP through its J-domain, and mutation of the HPD motif residue H517Q abolishes BiP binding and abolishes functional complementation of ER proteostasis phenotypes. |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for ER localization, supported by phylogenetic inference. UniProt indicates ER localization. The protein has a signal peptide. Reason: ER localization is well established for JEM1 family members. PMID:18754794 states "CaJem1p localized in the ER when expressed in S. cerevisiae." UniProt also annotates ER localization. The protein has a predicted signal peptide for ER targeting. Supporting Evidence: PMID:18754794 CaJem1p localized in the ER when expressed in S file:CANAL/JEM1/JEM1-deep-research-falcon.md CaJem1p-3HA expressed in S. cerevisiae exhibited perinuclear/ER localization and co-localized with BiP, supporting ER residency consistent with a luminal co-chaperone role. |
| GO:0034975 protein folding in endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for protein folding in the ER. JEM1 functions with BiP in ER protein quality control. Reason: Protein folding in the ER is a core function of JEM1. PMID:18754794 demonstrates that "expression of CaJem1p from a single-copy plasmid suppressed the temperature sensitive growth and the ER quality control defect of the jem1-delta scj1-delta mutant." This directly confirms CaJem1p functions in ER protein folding and quality control. Supporting Evidence: PMID:18754794 expression of CaJem1p from a single-copy plasmid suppressed the temperature sensitive growth and the ER quality control defect of the jem1Deltascj1Delta mutant, indicating that CaJem1p is functional in S. cerevisiae. file:CANAL/JEM1/JEM1-deep-research-falcon.md expression of CaJem1p from a single-copy plasmid suppressed temperature-sensitive growth and ER quality-control defects, and the HPD mutant failed to do so |
| GO:0051787 misfolded protein binding | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for misfolded protein binding. JEM1 is involved in ER protein quality control, which involves recognition of misfolded proteins. Reason: JEM1/Jem1p is involved in ER protein quality control alongside Scj1p and BiP/Kar2p. Quality control involves recognition and binding of misfolded proteins in the ER lumen. The IBA annotation is consistent with this role and is at an appropriate level of specificity for a J-domain co-chaperone involved in quality control. |
| GO:0005783 endoplasmic reticulum | IEA GO_REF:0000044 | ACCEPT | Summary: IEA annotation from UniProt subcellular location mapping. Consistent with the IBA annotation and experimental evidence. Reason: Duplicates the IBA annotation. ER localization is experimentally confirmed for CaJem1p (PMID:18754794). |
| GO:0000742 karyogamy involved in conjugation with cellular fusion | IGI PMID:18754794 Identification and characterization of a Jem1p ortholog of C... | KEEP AS NON CORE | Summary: IGI annotation for karyogamy (nuclear fusion during mating). Based on genetic interaction with S. cerevisiae jem1 mutant. CaJem1p can suppress the karyogamy defect when overexpressed. Reason: Karyogamy function is established for ScJem1p, and CaJem1p can partially complement this when overexpressed. However, this is not a core molecular function of the protein -- it is a downstream biological process mediated by its co-chaperone activity. Furthermore, PMID:18754794 shows the karyogamy function is less efficient for CaJem1p than ScJem1p due to weaker interaction with Nep98p. Mark as non-core. Supporting Evidence: PMID:18754794 CaJem1p suppressed the karyogamy defect of the jem1Deltamutant only when it was over-expressed from a multicopy plasmid. |
| GO:0005783 endoplasmic reticulum | ISS PMID:18754794 Identification and characterization of a Jem1p ortholog of C... | ACCEPT | Summary: ISS annotation for ER localization by sequence similarity. Consistent with direct experimental evidence. Reason: ER localization is directly demonstrated for CaJem1p in S. cerevisiae (PMID:18754794). This annotation is consistent with the IBA and IEA annotations. |
| GO:0005783 endoplasmic reticulum | IGI PMID:18754794 Identification and characterization of a Jem1p ortholog of C... | ACCEPT | Summary: IGI annotation for ER localization based on genetic interaction data. Reason: ER localization is confirmed by direct observation (PMID:18754794). Multiple evidence codes supporting the same correct localization is fine. |
| GO:0006457 protein folding | IGI PMID:18754794 Identification and characterization of a Jem1p ortholog of C... | ACCEPT | Summary: IGI annotation for protein folding based on genetic interaction with S. cerevisiae jem1 and scj1 mutants. Reason: Protein folding is a core function of JEM1. CaJem1p rescues the ER quality control defects of the jem1-delta scj1-delta mutant (PMID:18754794), directly demonstrating involvement in protein folding. Supporting Evidence: PMID:18754794 expression of CaJem1p from a single-copy plasmid suppressed the temperature sensitive growth and the ER quality control defect of the jem1Deltascj1Delta mutant |
| GO:0051082 unfolded protein binding | IGI PMID:18754794 Identification and characterization of a Jem1p ortholog of C... | MODIFY | Summary: IGI annotation for unfolded protein binding. GO:0051082 is now formally obsolete. JEM1 is a J-domain co-chaperone that assists BiP in protein folding in the ER. Reason: GO:0051082 is now formally obsolete. JEM1 functions as a co-chaperone for BiP/Kar2p in the ER, assisting in protein folding and quality control. The appropriate replacement is GO:0044183 "protein folding chaperone" which captures the chaperone activity of JEM1 in assisting protein folding via the Hsp70 system. JEM1 does not merely bind unfolded proteins passively; it actively participates in the folding cycle by stimulating BiP ATPase activity through its J-domain. Proposed replacements: protein folding chaperone Supporting Evidence: PMID:18754794 Jem1p is required for nuclear fusion during mating (karyogamy) and functions together with another J protein, Scj1p, in protein folding and quality control in the ER as a partner for the ER Hsp70 (BiP/Kar2p). |
| GO:0051087 protein-folding chaperone binding | IGI PMID:18754794 Identification and characterization of a Jem1p ortholog of C... | ACCEPT | Summary: IGI annotation for chaperone binding based on genetic interaction data. JEM1 binds to BiP/Kar2p as a co-chaperone. Reason: Binding to the ER Hsp70 chaperone BiP/Kar2p is a core function of JEM1. The J-domain directly interacts with and stimulates the ATPase activity of BiP. This annotation is consistent with the IBA annotation. |
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Download this section (compressed HTML)GOA was refreshed from remote. One previously reviewed row is no longer present in the current GOA
snapshot and was marked retired: true (review kept; not a biological REMOVE judgment):
No new GOA rows. Remaining judgments re-audited and left unchanged; core function MF stays
GO:0044183 protein folding chaperone (current term).
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