Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0000774 adenyl-nucleotide exchange factor activity	IBA GO_REF:0000033	ACCEPT	Summary: BAG2 is a nucleotide-exchange factor (NEF) for HSP70/HSC70, promoting ADP release via its BAG domain. This is the core molecular function and is well supported experimentally. Reason: NEF activity toward HSP70/HSC70 is the defining, experimentally validated molecular function of BAG2 and is consistent with the phylogenetic inference. Supporting Evidence: file:human/BAG2/BAG2-uniprot.txt a nucleotide-exchange factor (NEF) promoting the release of ADP from PMID:24318877 Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).
GO:0050821 protein stabilization	IBA GO_REF:0000033	ACCEPT	Summary: BAG2 stabilizes specific chaperone clients (CFTR, PINK1, ataxin-3) by reducing their ubiquitination, so protein stabilization is a supported core process. Reason: BAG2 lowers ubiquitination of clients such as PINK1 and pathogenic ataxin-3, stabilizing them, and stabilizes immature CFTR conformations. This is a well-supported outcome of BAG2 co-chaperone/CHIP-inhibitory activity. Supporting Evidence: PMID:24383081 which directly binds with and stabilises PINK1 by decreasing its ubiquitination PMID:25006867 stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
GO:0000774 adenyl-nucleotide exchange factor activity	IEA GO_REF:0000002	ACCEPT	Summary: NEF activity for HSP70/HSC70 is the defining molecular function of BAG2, well supported experimentally and consistent with the InterPro/BAG-domain inference. Reason: The BAG domain confers nucleotide-exchange activity on HSP70/HSC70; this IEA annotation agrees with direct biochemical evidence. Supporting Evidence: file:human/BAG2/BAG2-uniprot.txt a nucleotide-exchange factor (NEF) promoting the release of ADP from PMID:24318877 Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).
GO:0006457 protein folding	IEA GO_REF:0000117	ACCEPT	Summary: As an HSP70/HSC70 co-chaperone that regulates the chaperone cycle and can display intrinsic client-stabilizing activity, BAG2 participates in protein folding/refolding. Reason: BAG2 modulates HSP70/HSC70 chaperone activity and contributes to chaperone-assisted folding/maturation of clients (e.g., CFTR), supporting the protein folding process. Supporting Evidence: PMID:16207813 stimulates the chaperone-assisted maturation of CFTR
GO:0051087 protein-folding chaperone binding	IEA GO_REF:0000002	ACCEPT	Summary: BAG2 binds the ATPase domain of HSP70/HSC70 chaperones; chaperone binding is a core molecular feature underlying its co-chaperone/NEF role. Reason: Direct binding of BAG2 to the HSP/HSC70 ATPase domain is well established and is the basis of its NEF activity. Supporting Evidence: file:human/BAG2/BAG2-uniprot.txt Binds to the ATPase domain of HSP/HSC70 chaperones PMID:9873016 bind with high affinity (KD congruent with 1-10
GO:0051247 positive regulation of protein metabolic process	IEA GO_REF:0000117	MARK AS OVER ANNOTATED	Summary: This is an over-broad parent process term. BAG2's effects on protein metabolism are better captured by specific terms (protein stabilization, protein folding, negative regulation of ubiquitination). Reason: positive regulation of protein metabolic process is too general to convey BAG2 function and duplicates more specific accepted terms.
GO:0005515 protein binding	IPI PMID:18457437 Identification of intracellular proteins associated with the...	MARK AS OVER ANNOTATED	Summary: Generic high-throughput interactome/affinity-purification protein-binding annotation (EBNA5 TAP-MS); uninformative for BAG2 function. Reason: Bare protein binding from a proteomic screen does not identify a physiologically interpretable BAG2 molecular function.
GO:0005515 protein binding	IPI PMID:22365833 Dynamic protein-protein interaction wiring of the human spli...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a spliceosome interaction-mapping study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:22810586 Interpreting cancer genomes using systematic host network pe...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a tumour-virus host network perturbation screen; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:24510904 Unbiased screen for interactors of leucine-rich repeat kinas...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from an LRRK2 interactor screen; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:24981860 Human-chromatin-related protein interactions identify a deme...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a chromatin protein-interaction study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:25036637 A quantitative chaperone interaction network reveals the arc...	MARK AS OVER ANNOTATED	Summary: From a quantitative chaperone interaction network; the relevant BAG2 biology (HSP70 co-chaperone binding) is captured by specific chaperone-binding terms, so bare protein binding is uninformative here. Reason: Bare protein binding is too general; chaperone-network membership is better represented by protein-folding chaperone binding/complex terms.
GO:0005515 protein binding	IPI PMID:25852190 Integrative analysis of kinase networks in TRAIL-induced apo...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a TRAIL apoptosis kinase-network study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:25959826 Quantitative interaction proteomics of neurodegenerative dis...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a neurodegenerative-disease interaction proteomics study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:26496610 A human interactome in three quantitative dimensions organiz...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a quantitative interactome study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:29513927 Comparative Protein Interaction Network Analysis Identifies ...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a ROCO-protein interaction-network study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:29568061 An AP-MS- and BioID-compatible MAC-tag enables comprehensive...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a MAC-tag AP-MS/BioID mapping study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:30021884 Histone Interaction Landscapes Visualized by Crosslinking Ma...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a histone crosslinking-MS study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:31980649 Extensive rewiring of the EGFR network in colorectal cancer ...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from an EGFR-network rewiring study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome.	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from the binary interactome reference map; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a neurodegenerative-disease interactome study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a dual proteome-scale network study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:35167623 DNAJB1-PRKACA in HEK293T cells induces LINC00473 overexpress...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a DNAJB1-PRKACA signaling study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:35266954 The E3 ligase TRIM1 ubiquitinates LRRK2 and controls its loc...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a TRIM1/LRRK2 study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:35271311 OpenCell: Endogenous tagging for the cartography of human ce...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from the OpenCell endogenous-tagging study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:37045861 Interactome dynamics of RAF1-BRAF kinase monomers and dimers...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a RAF1-BRAF interactome study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0005515 protein binding	IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a multimodal cell-map study; uninformative for BAG2 function. Reason: Bare protein binding from a high-throughput interactome is not informative.
GO:0042802 identical protein binding	IPI PMID:22365833 Dynamic protein-protein interaction wiring of the human spli...	KEEP AS NON CORE	Summary: BAG2 self-association (homodimer) is a real biochemical property, but this particular annotation derives from a high-throughput spliceosome interaction map. Reason: BAG2 forms homodimers, so identical protein binding is plausible, but the supporting study is a generic interactome screen; retain as non-core.
GO:0042802 identical protein binding	IPI PMID:25036637 A quantitative chaperone interaction network reveals the arc...	KEEP AS NON CORE	Summary: BAG2 homodimerization is consistent with biochemistry; annotation from a chaperone interaction-network screen. Reason: Self-association is a genuine BAG2 property; retain as non-core given the high-throughput source.
GO:0042802 identical protein binding	IPI PMID:25416956 A proteome-scale map of the human interactome network.	KEEP AS NON CORE	Summary: BAG2 homodimerization is consistent with biochemistry; annotation from the proteome-scale interactome map. Reason: Self-association is a genuine BAG2 property; retain as non-core given the high-throughput source.
GO:0005874 microtubule	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: The BAG2/HSP70 complex is tethered to the microtubule in neurons; microtubule colocalization is supported but is a context-specific (neuronal) localization. Reason: Microtubule tethering is demonstrated for the tau-triage function but is a neuronal-context localization rather than the universal BAG2 site of action. Supporting Evidence: PMID:19228967 The BAG2/Hsp70 complex is tethered to the microtubule
GO:0030424 axon	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: Neuronal compartment localization inferred from the tau-triage microtubule work; context-specific. Reason: Axonal localization is a neuronal-context inference, not a core universal localization of BAG2.
GO:0030425 dendrite	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: Neuronal compartment localization inferred from the tau-triage microtubule work; context-specific. Reason: Dendritic localization is a neuronal-context inference, not a core universal localization of BAG2.
GO:0031072 heat shock protein binding	IEA GO_REF:0000107	ACCEPT	Summary: BAG2 binds the HSP70/HSC70 chaperone ATPase domain; heat shock protein binding is a core molecular feature. Reason: Direct binding of BAG2 to HSP/HSC70 is well established and underlies its co-chaperone/NEF activity. Supporting Evidence: file:human/BAG2/BAG2-uniprot.txt Binds to the ATPase domain of HSP/HSC70 chaperones
GO:0031397 negative regulation of protein ubiquitination	IEA GO_REF:0000120	ACCEPT	Summary: BAG2 inhibits CHIP-mediated ubiquitination of chaperone clients; negative regulation of protein ubiquitination is a core process. Reason: BAG2 abrogates CHIP/E2 cooperation and decreases ubiquitination of clients such as CFTR, PINK1, and ataxin-3. Supporting Evidence: PMID:16207813 BAG-2 inhibits the ubiquitin ligase activity of CHIP by abrogating the CHIP/E2 cooperation
GO:0031625 ubiquitin protein ligase binding	IEA GO_REF:0000107	ACCEPT	Summary: BAG2 binds and inhibits the E3 ubiquitin ligase CHIP (STUB1); ubiquitin protein ligase binding is supported and mechanistically central. Reason: BAG2 is a main component of CHIP complexes and binds CHIP to inhibit its ligase activity. Supporting Evidence: PMID:16207813 We identified the Hsc70 cochaperone
GO:0048156 tau protein binding	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: BAG2 (via the BAG2/HSP70 complex) captures misfolded/insoluble tau; tau binding is supported in the neuronal protein-triage context. Reason: Tau binding/capture is well documented but is a client-specific, neuronal-context activity rather than the universal BAG2 molecular function. Supporting Evidence: PMID:19228967 this complex can capture and deliver Tau to the
GO:1901588 dendritic microtubule	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: Neuronal dendritic-microtubule colocalization inferred from the tau-triage microtubule work; context-specific. Reason: Highly specific neuronal localization inference; retain as non-core.
GO:1901800 positive regulation of proteasomal protein catabolic process	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: In neurons BAG2/HSP70 delivers tau to the proteasome for ubiquitin-independent degradation, promoting proteasomal catabolism of this client. Reason: Supported by the tau-triage mechanism (ubiquitin-independent proteasomal degradation), but it is a client/context-specific role rather than a general one. Supporting Evidence: PMID:19228967 deliver Tau to the
GO:0048156 tau protein binding	NAS PMID:28386764 Roles of tau protein in health and disease.	KEEP AS NON CORE	Summary: Review-based assertion of BAG2-tau binding; consistent with the primary tau-triage data but context-specific (neuronal). Reason: Tau binding is real but client/context-specific; retain as non-core.
GO:0005874 microtubule	ISS PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	KEEP AS NON CORE	Summary: BAG2 associates with microtubules (even without tau) in the neuronal tau-triage work; supported but context-specific. Reason: Microtubule association is demonstrated but is a neuronal-context localization. Supporting Evidence: PMID:19228967 The BAG2/Hsp70 complex is tethered to the microtubule
GO:0030424 axon	ISS PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	KEEP AS NON CORE	Summary: Neuronal axonal localization inferred from the tau-triage study; context-specific. Reason: Axonal localization is a neuronal-context inference, not a core localization.
GO:0030425 dendrite	ISS PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	KEEP AS NON CORE	Summary: Neuronal dendritic localization inferred from the tau-triage study; context-specific. Reason: Dendritic localization is a neuronal-context inference, not a core localization.
GO:0031397 negative regulation of protein ubiquitination	ISS PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	ACCEPT	Summary: By inhibiting CHIP, BAG2 directs the HSP70-tau complex away from ubiquitination; negative regulation of protein ubiquitination is core. Reason: Consistent with BAG2's established CHIP-inhibitory, anti-ubiquitination role. Supporting Evidence: PMID:19228967 BAG2 directs the Hsp70-Tau complex away from ubiquitination
GO:0031397 negative regulation of protein ubiquitination	IDA PMID:24383081 The BAG2 protein stabilises PINK1 by decreasing its ubiquiti...	ACCEPT	Summary: BAG2 stabilizes PINK1 by decreasing its ubiquitination; direct support for negative regulation of protein ubiquitination. Reason: Direct experimental demonstration that BAG2 reduces client ubiquitination. Supporting Evidence: PMID:24383081 stabilises PINK1 by decreasing its ubiquitination
GO:0031397 negative regulation of protein ubiquitination	IDA PMID:25006867 The BAG2 and BAG5 proteins inhibit the ubiquitination of pat...	ACCEPT	Summary: BAG2 inhibits ubiquitination of pathogenic ataxin-3; direct support for negative regulation of protein ubiquitination. Reason: Direct experimental demonstration that BAG2 reduces client ubiquitination. Supporting Evidence: PMID:25006867 stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
GO:0032436 positive regulation of proteasomal ubiquitin-dependent protein catabolic process	ISS NOT PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	ACCEPT	Summary: The NOT annotation is well justified - BAG2 routes tau to a ubiquitin-INDEPENDENT proteasomal pathway while inhibiting CHIP, so it does not promote ubiquitin-dependent proteasomal catabolism. Reason: BAG2 mediates ubiquitin-independent proteasomal degradation of tau and inhibits the ubiquitin-dependent CHIP route, supporting the negation. Supporting Evidence: PMID:19228967 BAG2 mediates ubiquitin independent degradation of Tau through the proteasome
GO:0050821 protein stabilization	IDA PMID:24383081 The BAG2 protein stabilises PINK1 by decreasing its ubiquiti...	ACCEPT	Summary: BAG2 directly stabilizes PINK1 by decreasing its ubiquitination; core process. Reason: Direct experimental demonstration of BAG2-mediated client stabilization. Supporting Evidence: PMID:24383081 directly binds with and stabilises PINK1 by decreasing its ubiquitination
GO:0050821 protein stabilization	IDA PMID:25006867 The BAG2 and BAG5 proteins inhibit the ubiquitination of pat...	ACCEPT	Summary: BAG2 stabilizes pathogenic ataxin-3 by inhibiting its ubiquitination; core process. Reason: Direct experimental demonstration of BAG2-mediated client stabilization. Supporting Evidence: PMID:25006867 stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
GO:1901588 dendritic microtubule	ISS PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	KEEP AS NON CORE	Summary: Neuronal dendritic-microtubule colocalization from the tau-triage study; context-specific. Reason: Highly specific neuronal localization; retain as non-core.
GO:1901800 positive regulation of proteasomal protein catabolic process	ISS PMID:19228967 The cochaperone BAG2 sweeps paired helical filament- insolub...	KEEP AS NON CORE	Summary: BAG2/HSP70 promotes ubiquitin-independent proteasomal degradation of tau; supported but client/context-specific. Reason: Supported by the tau-triage mechanism but context-specific to neuronal tau handling. Supporting Evidence: PMID:19228967 deliver Tau to the
GO:0005515 protein binding	IPI PMID:16207813 BAG-2 acts as an inhibitor of the chaperone-associated ubiqu...	MARK AS OVER ANNOTATED	Summary: The underlying interaction is BAG2 with CHIP (and HSC70); bare protein binding is too generic and is better captured by the specific chaperone/E3-ligase binding terms. Reason: protein binding is uninformative; the specific BAG2-CHIP and BAG2-HSC70 interactions are represented by other terms in this review.
GO:0010954 positive regulation of protein processing	IMP PMID:16207813 BAG-2 acts as an inhibitor of the chaperone-associated ubiqu...	KEEP AS NON CORE	Summary: BAG2 stimulates chaperone-assisted maturation of CFTR; this is better captured as client stabilization/folding and negative regulation of ubiquitination. The generic "protein processing" term is a loose fit. Reason: Supported for CFTR maturation but client/context-specific, and the term is a somewhat imprecise description of BAG2's CHIP-inhibition/stabilization mechanism. Supporting Evidence: PMID:16207813 stimulates the chaperone-assisted maturation of CFTR
GO:0044325 transmembrane transporter binding	IPI PMID:16207813 BAG-2 acts as an inhibitor of the chaperone-associated ubiqu...	KEEP AS NON CORE	Summary: BAG2 recognizes CFTR (a transmembrane transporter) NBD1 peptides and stabilizes immature CFTR; transmembrane transporter binding is supported but client-specific. Reason: CFTR is one client of BAG2; the binding is supported but not the universal core molecular function. Supporting Evidence: PMID:16207813 also to stabilize immature CFTR conformations
GO:0050821 protein stabilization	IDA PMID:16207813 BAG-2 acts as an inhibitor of the chaperone-associated ubiqu...	ACCEPT	Summary: BAG2 stabilizes immature CFTR conformations in addition to inhibiting CHIP; protein stabilization is a core BAG2 process. Reason: Direct evidence that BAG2 stabilizes a chaperone client (CFTR). Supporting Evidence: PMID:16207813 also to stabilize immature CFTR conformations
GO:0051087 protein-folding chaperone binding	IPI PMID:16207813 BAG-2 acts as an inhibitor of the chaperone-associated ubiqu...	ACCEPT	Summary: BAG2 binds HSC70 (a protein-folding chaperone) within CHIP complexes; chaperone binding is core. Reason: Direct evidence of BAG2 association with HSC70 chaperone complexes underlies its co-chaperone function. Supporting Evidence: PMID:16207813 the Hsc70 cochaperone
GO:0101031 protein folding chaperone complex	IPI PMID:16207813 BAG-2 acts as an inhibitor of the chaperone-associated ubiqu...	ACCEPT	Summary: BAG2 is a component of HSC70/CHIP chaperone complexes; membership in a protein-folding chaperone complex is core. Reason: BAG2 is a main component of CHIP/HSC70 chaperone complexes, consistent with its co-chaperone role. Supporting Evidence: PMID:16207813 We identified the Hsc70 cochaperone
GO:0000774 adenyl-nucleotide exchange factor activity	IDA PMID:24318877 Binding of human nucleotide exchange factors to heat shock p...	ACCEPT	Summary: Direct biochemical demonstration of BAG2 NEF activity toward HSP70 (HSPA1A); this is the core molecular function. Reason: BAG2 binds Hsp72 and functions in nucleotide/peptide release assays as a NEF, directly validating this molecular function. Supporting Evidence: PMID:24318877 Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70). PMID:24318877 their relative affinity values
GO:0005515 protein binding	IPI PMID:24318877 Binding of human nucleotide exchange factors to heat shock p...	MARK AS OVER ANNOTATED	Summary: The underlying interaction is BAG2 with HSP70 (HSPA1A); generic protein binding is uninformative and is captured by specific chaperone-binding/NEF terms. Reason: Bare protein binding is too general; the BAG2-HSP70 interaction is represented by heat shock protein binding and NEF activity.
GO:0005829 cytosol	TAS Reactome:R-HSA-5252079	ACCEPT	Summary: BAG2 is a cytosolic co-chaperone; cytosolic localization is the core compartment for its HSP70 NEF/CHIP-regulatory activity. Reason: Consistent with BAG2 acting on cytosolic HSP70/HSC70 and CHIP complexes. Supporting Evidence: file:human/BAG2/BAG2-uniprot.txt Co-chaperone for HSP70 and HSC70 chaperone proteins
GO:0019538 protein metabolic process	IDA PMID:9873015 Control of glycogen synthesis in cultured human muscle cells...	REMOVE	Summary: The cited reference (PMID:9873015) is about glycogen synthesis in muscle cells and does not concern BAG2; this is a wrong-reference curation error rather than a genuine (if over-broad) annotation. Reason: The cited reference (PMID:9873015, "Control of glycogen synthesis in cultured human muscle cells") contains no evidence for any BAG2 role - it is a database mis-attribution. The annotation is unlikely to be correct based on the combined evidence and should be removed at source rather than merely downgraded.
GO:0006457 protein folding	TAS PMID:9873016 An evolutionarily conserved family of Hsp70/Hsc70 molecular ...	ACCEPT	Summary: As an HSP70/HSC70 chaperone regulator, BAG2 participates in protein folding; supported by the foundational BAG-family chaperone-regulator study. Reason: BAG2 modulates HSP70/HSC70 chaperone activity, consistent with a protein folding role. Supporting Evidence: PMID:9873016 modulating their

Core Functions

BAG2 acts as a nucleotide-exchange factor (NEF) for the HSP70/HSC70 molecular chaperones, binding the chaperone ATPase domain via its BAG domain and promoting ADP release to regulate the chaperone cycle and client release.

Molecular Function:

adenyl-nucleotide exchange factor activity

Directly Involved In:

protein folding

Cellular Locations:

cytosol

Supporting Evidence:

file:human/BAG2/BAG2-uniprot.txt
a nucleotide-exchange factor (NEF) promoting the release of ADP from
PMID:24318877
Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).

BAG2 inhibits the chaperone-associated E3 ubiquitin ligase CHIP (STUB1) by abrogating CHIP/E2 cooperation, thereby negatively regulating ubiquitination of chaperone clients and shifting protein triage away from degradation.

Molecular Function:

ubiquitin protein ligase binding

Directly Involved In:

negative regulation of protein ubiquitination

Cellular Locations:

cytosol

Supporting Evidence:

PMID:16207813
BAG-2 inhibits the ubiquitin ligase activity of CHIP by abrogating the CHIP/E2 cooperation

BAG2 stabilizes specific chaperone clients (e.g., immature CFTR, PINK1, polyglutamine-expanded ataxin-3) by decreasing their ubiquitination, contributing to chaperone-assisted protein quality control.

Molecular Function:

protein-folding chaperone binding

Directly Involved In:

protein stabilization

Cellular Locations:

cytosol

Supporting Evidence:

PMID:24383081
directly binds with and stabilises PINK1 by decreasing its ubiquitination
PMID:25006867
stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000107

Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:16207813

BAG-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase CHIP.

PMID:18457437

Identification of intracellular proteins associated with the EBV-encoded nuclear antigen 5 using an efficient TAP procedure and FT-ICR mass spectrometry.

PMID:19228967

The cochaperone BAG2 sweeps paired helical filament- insoluble tau from the microtubule.

PMID:22365833

Dynamic protein-protein interaction wiring of the human spliceosome.

PMID:22810586

Interpreting cancer genomes using systematic host network perturbations by tumour virus proteins.

PMID:24318877

Binding of human nucleotide exchange factors to heat shock protein 70 (Hsp70) generates functionally distinct complexes in vitro.

PMID:24383081

The BAG2 protein stabilises PINK1 by decreasing its ubiquitination.

PMID:24510904

Unbiased screen for interactors of leucine-rich repeat kinase 2 supports a common pathway for sporadic and familial Parkinson disease.

PMID:24981860

Human-chromatin-related protein interactions identify a demethylase complex required for chromosome segregation.

PMID:25006867

The BAG2 and BAG5 proteins inhibit the ubiquitination of pathogenic ataxin3-80Q.

PMID:25036637

A quantitative chaperone interaction network reveals the architecture of cellular protein homeostasis pathways.

PMID:25416956

A proteome-scale map of the human interactome network.

PMID:25852190

Integrative analysis of kinase networks in TRAIL-induced apoptosis provides a source of potential targets for combination therapy.

PMID:25959826

Quantitative interaction proteomics of neurodegenerative disease proteins.

PMID:26496610

A human interactome in three quantitative dimensions organized by stoichiometries and abundances.

PMID:28386764

Roles of tau protein in health and disease.

PMID:29513927

Comparative Protein Interaction Network Analysis Identifies Shared and Distinct Functions for the Human ROCO Proteins.

PMID:29568061

An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations.

PMID:30021884

Histone Interaction Landscapes Visualized by Crosslinking Mass Spectrometry in Intact Cell Nuclei.

PMID:31980649

Extensive rewiring of the EGFR network in colorectal cancer cells expressing transforming levels of KRAS(G13D).

PMID:32296183

A reference map of the human binary protein interactome.

PMID:32814053

Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.

PMID:33961781

Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.

PMID:34831344

With or without You: Co-Chaperones Mediate Health and Disease by Modifying Chaperone Function and Protein Triage.

Review framing BAG2 as an HSP70/HSC70 co-chaperone that modulates chaperone function and protein triage decisions (folding/stabilization vs degradation) in health and disease, consistent with its inhibition of CHIP/STUB1-mediated client ubiquitination.

PMID:35167623

DNAJB1-PRKACA in HEK293T cells induces LINC00473 overexpression that depends on PKA signaling.

PMID:35266954

The E3 ligase TRIM1 ubiquitinates LRRK2 and controls its localization, degradation, and toxicity.

PMID:35271311

OpenCell: Endogenous tagging for the cartography of human cellular organization.

PMID:37045861

Interactome dynamics of RAF1-BRAF kinase monomers and dimers.

PMID:39300217

BAG2, MAD2L1, and MDK are cancer-driver genes and candidate targets for novel therapies in malignant pleural mesothelioma.

BAG2 is identified as a candidate cancer-driver gene and diagnostic-adjunct biomarker in malignant pleural mesothelioma, being significantly upregulated in tumor RNA-seq and showing moderate-to-strong immunohistochemical expression in mesothelioma but not in reactive mesothelium; this is a disease-association rather than a new molecular function for BAG2.

PMID:40205054

Multimodal cell maps as a foundation for structural and functional genomics.

PMID:9873015

Control of glycogen synthesis in cultured human muscle cells.

PMID:9873016

An evolutionarily conserved family of Hsp70/Hsc70 molecular chaperone regulators.

Reactome:R-HSA-5252079

HSP110s exchange ATP for ADP on HSP70s:ADP

file:human/BAG2/BAG2-uniprot.txt

BAG2 UniProtKB record (O95816)

file:human/BAG2/BAG2-notes.md

Manual BAG2 curation notes

Suggested Experiments

Experiment: Reconstitute HSC70/CHIP/E2 ubiquitination assays with purified BAG2 across a panel of clients (CFTR NBD1, PINK1, ataxin-3, tau) and quantify client-specific suppression of ubiquitination versus NEF activity.

Hypothesis: BAG2 selectively inhibits CHIP-mediated ubiquitination of a defined subset of HSP70 clients rather than acting as a global CHIP inhibitor.

Type: in vitro reconstituted ubiquitination assay

Experiment: Use neurons with BAG2 BAG-domain or microtubule-association mutants and measure Sarkosyl-insoluble/phospho-tau clearance, proteasome dependence, and ubiquitin requirement.

Hypothesis: BAG2 routes misfolded tau to ubiquitin-independent proteasomal degradation via microtubule tethering of the BAG2/HSP70 complex.

Type: cell-based tau clearance / proteasome dependence assay

Deep Research

Falcon

(BAG2-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 17 citations 2 artifacts 2026-06-07T05:01:30.651877

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000021 The figure panels showing BAG-2 inhibition of CHIP-mediated ubiquitylation and gel filtration complexes were found in Figures 4 and (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Human BAG2 (BAG cochaperone 2; UniProt O95816)—functional annotation and recent research

1) Identity verification, key concepts, and definitions

Target identity. The queried gene symbol BAG2 corresponds to Bcl-2–associated athanogene 2 (BAG-2), a human BAG-family co‑chaperone recovered as a major component of CHIP/STUB1-containing complexes in human cells. (arndt2005bag2actsas pages 1-2, arndt2005bag2actsas pages 2-3)

Domain architecture (current understanding). BAG2 contains (i) a C‑terminal BAG domain that binds the ATPase (nucleotide-binding) domain of Hsp70-family chaperones (Hsc70/Hsp70), consistent with BAG proteins functioning as nucleotide exchange factors (NEFs), and (ii) an N‑terminal coiled‑coil implicated in homodimerization. (arndt2005bag2actsas pages 3-5, schonbuhler2016bag2interfereswith pages 1-3)

Functional definition (protein triage context). In proteostasis, “protein triage” refers to how chaperone systems decide whether a client protein is refolded, held, or targeted to degradation. BAG2 is best-supported as a regulator of triage within the Hsp70/Hsc70–CHIP/STUB1 axis by (a) accelerating the Hsp70 ATPase cycle (NEF activity) and (b) inhibiting CHIP/STUB1 E3 ubiquitin ligase activity, thereby shifting the balance away from ubiquitination-driven degradation for specific substrates/contexts. (schonbuhler2016bag2interfereswith pages 1-3, altinok2021withorwithout pages 12-13)

2) Experimentally supported molecular functions and mechanisms

2.1 BAG2 as a NEF/co-chaperone for Hsp70/Hsc70

The BAG domain of BAG2 binds the Hsp70-family ATPase domain and facilitates nucleotide exchange, supporting a direct role in modulating Hsp70/Hsc70 client processing. (schonbuhler2016bag2interfereswith pages 1-3)

2.2 BAG2 as an inhibitor of CHIP/STUB1 ubiquitin ligase activity

Foundational biochemical evidence (in vitro + cell complexes). Arndt et al. (2005) demonstrated that BAG2 forms ternary complexes with Hsc70 and CHIP/STUB1 in human cells and that purified BAG2 strongly inhibits CHIP-mediated ubiquitylation of client proteins (e.g., Raf‑1) and also reduces ubiquitylation of Hsc70. (arndt2005bag2actsas pages 3-5)

The associated figure evidence shows dose-dependent suppression of CHIP-mediated ubiquitination of Raf‑1/Hsc70 by increasing BAG2 concentration. (arndt2005bag2actsas media 4ec539ab)

Cellular evidence (Hsp70 family substrate stabilization). In primary human fibroblasts, BAG2 prevents CHIP-mediated ubiquitination of HSP72 (HSPA1A/HSPA1B) and stabilizes HSP72 at the protein level without increasing HSP72 mRNA, consistent with post‑translational protection from CHIP-dependent ubiquitination. (schonbuhler2016bag2interfereswith pages 3-6)

Mechanistically, BAG2 inhibits CHIP activity by disrupting CHIP cooperation with E2 ubiquitin-conjugating enzymes (e.g., UBCH5A/UBCH5B described across these studies). (schonbuhler2016bag2interfereswith pages 1-3, schonbuhler2016bag2interfereswith pages 6-8)

2.3 BAG2 participates in large proteostasis complexes (complex recruitment hypothesis)

Gel filtration and immunoprecipitation evidence indicates BAG2 co-fractionates with Hsc70 and CHIP in high-molecular-mass complexes, supporting a role in assembling/recruiting the Hsc70/CHIP machinery to distinct complexes or structures. (arndt2005bag2actsas pages 3-5)

Figure evidence supports co-fractionation of BAG2 with Hsc70 and CHIP in large complexes in vitro and in cell extracts. (arndt2005bag2actsas media 2bb89edf)

3) Subcellular localization and where BAG2 acts

Across the retrieved primary mechanistic studies, BAG2 is experimentally supported as a component of large intracellular chaperone/E3-ligase complexes containing Hsc70/Hsp70 and CHIP, but the excerpts do not provide a definitive compartment assignment (e.g., nucleus vs cytosol vs organellar localization) or high-resolution localization mapping. (arndt2005bag2actsas pages 3-5)

A 2024 fibrolamellar carcinoma model positions BAG2 within DNAJ‑PKAc/Hsp70 signaling scaffolds whose behavior includes cytosolic diffusion and altered interaction networks; BAG2 recruitment to DNAJ‑PKAc depends on an Hsp70-binding competent fusion protein, implicating BAG2 action in chaperone-linked signaling complexes in the cytosolic compartment in that model system. (lauer2024recruitmentofbag2 pages 5-9, lauer2024recruitmentofbag2 pages 17-21)

4) Pathways and biological processes

4.1 Proteostasis and ubiquitin–proteasome system (UPS)

The best-supported pathway assignment for BAG2 is proteostasis regulation through the Hsp70/Hsc70–CHIP/STUB1 axis, where BAG2 (i) modulates Hsp70 nucleotide cycling and (ii) inhibits CHIP ubiquitin ligase activity, altering whether chaperone-bound substrates proceed toward ubiquitination and degradation. (schonbuhler2016bag2interfereswith pages 1-3, arndt2005bag2actsas pages 3-5)

4.2 Aging-associated proteostasis changes

In a cellular aging/senescence context, BAG2 and CHIP protein levels rise in senescent fibroblasts, while HSP72 ubiquitination is reduced—consistent with BAG2 counteracting increased CHIP abundance and contributing to altered proteostasis with age. (schonbuhler2016bag2interfereswith pages 6-8, schonbuhler2016bag2interfereswith pages 3-6)

4.3 Apoptosis regulation (disease-context mechanistic pathway)

A 2024 gastric cancer study proposes a mechanistic axis in which BAG2 interacts with CHIP to inhibit HSP70 ubiquitination/degradation, increasing HSP70 association with Apaf1 and reducing mitochondrial cytochrome c release, thereby suppressing intrinsic apoptosis (“BAG2–CHIP–HSP70–Apaf1–Cytc”). (liu2024blockageofbag2chip pages 1-5, liu2024blockageofbag2chip pages 8-10)

In a 2024 fibrolamellar carcinoma model, BAG2 supports survival and resistance to drug-induced apoptosis in cells driven by the DNAJ‑PKAc fusion, and BAG2 knockout restores apoptotic sensitivity to etoposide (e.g., increased PARP cleavage). (lauer2024recruitmentofbag2 pages 17-21)

4.4 Autophagy/mitophagy and innate immunity—evidence status in this retrieval

Although CHIP is broadly discussed in the literature as participating in UPS and (contextually) autophagy-linked triage, the retrieved evidence set here does not provide direct BAG2-specific experimental evidence for autophagy/mitophagy regulation or innate immune pathway control. Claims in these areas should therefore be treated as not established from the current retrieved excerpts rather than inferred. (schonbuhler2016bag2interfereswith pages 1-3)

5) Recent developments (prioritizing 2023–2024)

5.1 Neurodegeneration (computational network modeling; 2023)

A 2023 study analyzed Alzheimer’s disease (AD) microarray data and highlighted a “BAG2–HSC70–STUB1–MAPT” network as correlated with disease occurrence/progression; it reported that a neural network model predicting MMSE from gene expression achieved accuracy up to 0.93, and an SVM classifier achieved accuracy 0.72. This supports BAG2 as part of a proteostasis-associated expression signature in AD, but it is not direct biochemical mechanism. (OpenTargets Search: -BAG2)

5.2 Malignant pleural mesothelioma (MPM; 2024)

Bisceglia et al. (published Sep 2024) identified BAG2 (ENSG00000112208) as significantly upregulated in MPM RNA-seq (example DE statistics reported: log2FC 1.55, padj 0.0019) and validated findings in an independent cohort of 211 MPM patients; the study also analyzed a separate set of 40 MPM specimens for subtype and IHC work. (bisceglia2024bag2mad2l1and pages 2-3, bisceglia2024bag2mad2l1and pages 1-2)

IHC evidence showed moderate to strong BAG2 expression in MPM subtypes with no visible expression in hyperplastic mesothelium (RMP) in representative analyses, supporting BAG2 as a candidate diagnostic adjunct marker (with the caveat that full sensitivity/specificity is not present in the provided excerpts). (bisceglia2024bag2mad2l1and pages 9-12)

5.3 Liposarcoma prognostic associations (2024)

In liposarcoma, high BAG2 expression was associated with a higher-risk profile and immune microenvironment differences (e.g., increased M2 macrophage proportion and negative relationship with CD4+ T-cell infiltration) and correlates with transcriptional regulators (e.g., PPARG r = −0.63, p < 2.2×10−16; NFKB1 r = 0.5, p = 3.1×10−10). (lian2024decipheringtheprognostic pages 9-12)

5.4 Fibrolamellar carcinoma (FLC) mechanistic expansion (2024)

A 2024 bioRxiv study identified BAG2 by proximity proteomics as enriched near the DNAJ‑PKAc fusion kinase and validated Hsp70-dependent recruitment of BAG2 (loss of BAG2 binding when an Hsp70-binding–defective DNAJ-PKAc mutant is used). BAG2 also showed evidence of phosphorylation (Ser20) consistent with basophilic kinase motifs in that system. (lauer2024recruitmentofbag2 pages 13-17)

The same study reported increased BAG2 protein levels in FLC versus adjacent normal liver and a trend toward higher levels in metastasis (as assessed by immunoblot/IHC/IF in a limited number of samples described in the excerpt). (lauer2024recruitmentofbag2 pages 13-17)

5.5 Gastric cancer therapeutic axis proposal (2024)

A 2024 Research Square preprint integrated TCGA data (n = 392) and IHC on 152 paired tumor/adjacent tissues to report elevated BAG2 and poor prognosis association in gastric cancer. Mechanistically, BAG2 knockout increased apoptosis (Annexin V/PI, TUNEL, apoptosome formation) and reduced xenograft tumor growth; the work proposes FIIN‑2 as an inhibitor of the BAG2–CHIP complex, effective in GC cell lines, organoids, and CDX models. (liu2024blockageofbag2chip pages 8-10, liu2024blockageofbag2chip pages 1-5)

6) Current applications and real-world implementations

Biomarker use cases (emerging). Evidence supports BAG2 being investigated as a biomarker in multiple cancers: MPM vs RMP discrimination by IHC (2024), correlation with advanced disease/metastasis in FLC (2024 preprint), and prognostic association signatures in gastric cancer (2024 preprint) and liposarcoma (2024). (bisceglia2024bag2mad2l1and pages 9-12, lauer2024recruitmentofbag2 pages 13-17, liu2024blockageofbag2chip pages 8-10, lian2024decipheringtheprognostic pages 9-12)

Therapeutic targeting (preclinical). Two practical intervention angles are supported by 2024 studies: (i) direct targeting of the BAG2–CHIP interaction (FIIN‑2 proposed in gastric cancer), and (ii) exploiting BAG2-linked apoptosis resistance via combination therapy (etoposide + navitoclax) in a DNAJ‑PKAc-driven FLC cell model. (liu2024blockageofbag2chip pages 1-5, lauer2024recruitmentofbag2 pages 17-21)

7) Expert synthesis/interpretation (grounded in authoritative sources)

Across foundational and recent studies, the unifying mechanistic theme is that BAG2 acts as a tunable brake on CHIP/STUB1-mediated ubiquitination within Hsp70/Hsc70 client-handling pathways. This offers a plausible explanation for why BAG2 can be associated with increased survival/chemoresistance in several tumor contexts: stabilizing Hsp70-family chaperones and/or specific client proteins can favor stress tolerance and anti-apoptotic states. (arndt2005bag2actsas pages 3-5, schonbuhler2016bag2interfereswith pages 3-6, lauer2024recruitmentofbag2 pages 17-21)

At the same time, the same mechanism makes BAG2 biology context-dependent: inhibiting CHIP can protect certain proteins from degradation (pro-survival), but may also interfere with removal of damaged proteins in other contexts (proteostasis burden). The primary mechanistic literature supports this as a triage regulator rather than a single “pathway on/off” switch. (schonbuhler2016bag2interfereswith pages 1-3, altinok2021withorwithout pages 12-13)

8) Key quantitative/statistical highlights (recent)

MPM RNA-seq differential expression: BAG2 upregulated with log2FC 1.55, padj 0.0019 in one reported analysis; validation cohort n = 211 and tissue cohort n = 40 described. (bisceglia2024bag2mad2l1and pages 2-3, bisceglia2024bag2mad2l1and pages 1-2)
Gastric cancer cohorts: TCGA analysis n = 392; IHC tissue microarrays n = 152 paired tumors/adjacent tissues; BAG2 KO increased apoptosis and reduced xenograft growth (quantitative details referenced to assays in excerpt). (liu2024blockageofbag2chip pages 8-10)
FLC proteomics and drug response: proximity proteomics identified 1,174 proteins (261 significant); combination etoposide+navitoclax reduced AML12DNAJ‑PKAc viability to 0.450 ± 0.042 vs etoposide and 0.163 ± 0.012 vs vehicle (SEM, n=3). (lauer2024recruitmentofbag2 pages 5-9, lauer2024recruitmentofbag2 pages 17-21)
Liposarcoma correlations: PPARG r = −0.63 (p < 2.2×10−16); NFKB1 r = 0.5 (p = 3.1×10−10) in association with BAG2 expression. (lian2024decipheringtheprognostic pages 9-12)

9) Evidence map (summary table)

The following table consolidates the main functional-annotation claims and where the strongest evidence lies.

Category	Evidence summary	Key sources (year, journal, URL, context ids)
Identity/domains	Human BAG2 corresponds to BCL2-associated athanogene 2 / BAG family molecular chaperone regulator 2, a BAG-family co-chaperone identified in CHIP-containing complexes. Retrieved evidence supports a C-terminal BAG domain that binds the ATPase domain of Hsc70/Hsp70 and an N-terminal coiled-coil region that mediates homodimerization; BAG2 lacks the ubiquitin-like domain present in BAG1. Retrieved excerpts did not explicitly state UniProt O95816, but the protein identity, BAG-domain architecture, and human-cell context align with the requested target. (arndt2005bag2actsas pages 2-3, arndt2005bag2actsas pages 3-5, arndt2005bag2actsas pages 1-2, schonbuhler2016bag2interfereswith pages 1-3, heymann2019cterminusofhsp70 pages 24-27)	Arndt et al., 2005, Molecular Biology of the Cell, https://doi.org/10.1091/mbc.e05-07-0660 (arndt2005bag2actsas pages 2-3, arndt2005bag2actsas pages 3-5, arndt2005bag2actsas pages 1-2); Schönbühler et al., 2016, International Journal of Molecular Sciences, https://doi.org/10.3390/ijms18010069 (schonbuhler2016bag2interfereswith pages 1-3); Heymann, 2019, thesis/article excerpt, no journal metadata in excerpt (heymann2019cterminusofhsp70 pages 24-27)
Molecular function	BAG2 functions as an HSP70/HSC70 co-chaperone and nucleotide-exchange factor, promoting ADP/ATP exchange on HSP70-family chaperones. A core experimentally supported role is inhibition of CHIP/STUB1 E3 ligase activity, including disruption of CHIP–E2 cooperation and suppression of CHIP-mediated ubiquitination of HSP72 and Raf-1; BAG2 can also bind misfolded proteins and reduce aggregation, shifting protein triage toward stabilization/folding rather than degradation. (schonbuhler2016bag2interfereswith pages 6-8, schonbuhler2016bag2interfereswith pages 1-3, arndt2005bag2actsas pages 3-5, schonbuhler2016bag2interfereswith pages 3-6, altinok2021withorwithout pages 12-13, arndt2005bag2actsas media 4ec539ab)	Arndt et al., 2005, Molecular Biology of the Cell, https://doi.org/10.1091/mbc.e05-07-0660 (arndt2005bag2actsas pages 3-5, arndt2005bag2actsas media 4ec539ab); Schönbühler et al., 2016, International Journal of Molecular Sciences, https://doi.org/10.3390/ijms18010069 (schonbuhler2016bag2interfereswith pages 6-8, schonbuhler2016bag2interfereswith pages 1-3, schonbuhler2016bag2interfereswith pages 3-6); Altinok et al., 2021, Cells, https://doi.org/10.3390/cells10113121 (altinok2021withorwithout pages 12-13)
Key partners/clients	Strongest supported partners are Hsc70/Hsp70 family chaperones and CHIP/STUB1. BAG2 forms ternary complexes with Hsc70/Hsp70 and CHIP, and reported clients/substrates modulated through this axis include HSP72, Hsc70, Raf-1, CFTR maturation machinery, and in newer cancer studies HSP70/Apaf1/Cytochrome c signaling components. In fibrolamellar carcinoma, BAG2 recruitment to DNAJ-PKAc scaffolds is Hsp70-dependent; in gastric cancer, BAG2 forms a BAG2–CHIP–HSP70 complex affecting Apaf1/Cyt c apoptosis signaling. (schonbuhler2016bag2interfereswith pages 1-3, arndt2005bag2actsas pages 3-5, liu2024blockageofbag2chip pages 8-10, lauer2024recruitmentofbag2 pages 17-21, lauer2024recruitmentofbag2 pages 13-17)	Arndt et al., 2005, Molecular Biology of the Cell, https://doi.org/10.1091/mbc.e05-07-0660 (arndt2005bag2actsas pages 3-5); Schönbühler et al., 2016, International Journal of Molecular Sciences, https://doi.org/10.3390/ijms18010069 (schonbuhler2016bag2interfereswith pages 1-3); Liu et al., 2024, Research Square preprint, https://doi.org/10.21203/rs.3.rs-4285523/v1 (liu2024blockageofbag2chip pages 8-10); Lauer et al., 2024, bioRxiv, https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 17-21, lauer2024recruitmentofbag2 pages 13-17)
Pathways	BAG2 is most strongly linked to proteostasis/protein quality control, especially the HSP70/HSC70–CHIP axis and ubiquitin-proteasome triage. Evidence also connects BAG2 to chaperone-assisted maturation of CFTR, aging-associated proteostasis changes, mitochondrial/intrinsic apoptosis through HSP70–Apaf1–cytochrome c signaling in gastric cancer, and Hsp70-linked pro-survival scaffolding in fibrolamellar carcinoma. Retrieved excerpts mention autophagy as a CHIP-related context, but direct BAG2-specific autophagy/mitophagy evidence was limited in the retrieved texts. Innate-immunity regulation was not directly supported by the gathered excerpts. (liu2024blockageofbag2chip pages 1-5, schonbuhler2016bag2interfereswith pages 1-3, liu2024blockageofbag2chip pages 8-10, schonbuhler2016bag2interfereswith pages 3-6, arndt2005bag2actsas pages 1-2, lauer2024recruitmentofbag2 pages 1-5, lauer2024recruitmentofbag2 pages 17-21)	Arndt et al., 2005, Molecular Biology of the Cell, https://doi.org/10.1091/mbc.e05-07-0660 (arndt2005bag2actsas pages 1-2); Schönbühler et al., 2016, International Journal of Molecular Sciences, https://doi.org/10.3390/ijms18010069 (schonbuhler2016bag2interfereswith pages 1-3, schonbuhler2016bag2interfereswith pages 3-6); Liu et al., 2024, Research Square preprint, https://doi.org/10.21203/rs.3.rs-4285523/v1 (liu2024blockageofbag2chip pages 1-5, liu2024blockageofbag2chip pages 8-10); Lauer et al., 2024, bioRxiv, https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 1-5, lauer2024recruitmentofbag2 pages 17-21)
Localization/complexes	Retrieved evidence supports BAG2 existing in large cytosolic/high-molecular-mass protein complexes with Hsc70 and CHIP (reported by gel filtration and immunoprecipitation), and suggests BAG2 may recruit the Hsc70/CHIP machinery to distinct protein complexes or subcellular structures. In DNAJ-PKAc models, BAG2 is recruited into Hsp70-dependent signaling scaffolds. However, precise steady-state subcellular localization was not well specified in the retrieved excerpts and should be treated as incompletely resolved here. (arndt2005bag2actsas pages 3-5, arndt2005bag2actsas media 4ec539ab, lauer2024recruitmentofbag2 pages 13-17, lauer2024recruitmentofbag2 pages 5-9)	Arndt et al., 2005, Molecular Biology of the Cell, https://doi.org/10.1091/mbc.e05-07-0660 (arndt2005bag2actsas pages 3-5, arndt2005bag2actsas media 4ec539ab); Lauer et al., 2024, bioRxiv, https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 13-17, lauer2024recruitmentofbag2 pages 5-9)
2023-2024 developments	Recent studies expand BAG2 beyond classical proteostasis: a 2023 AD network study linked BAG2-HSC70-STUB1-MAPT expression patterns to Alzheimer’s disease progression; 2024 studies implicated BAG2 as a prognostic/functional driver candidate in liposarcoma and malignant pleural mesothelioma, a pro-survival factor recruited to DNAJ-PKAc/Hsp70 scaffolds in fibrolamellar carcinoma, and an oncogenic regulator of the BAG2–CHIP–HSP70 axis in gastric cancer. These newer reports are more disease-contextual than foundational mechanistic studies but consistently reinforce BAG2 as a regulator of chaperone-dependent protein triage and apoptosis resistance. (liu2024blockageofbag2chip pages 8-10, lian2024decipheringtheprognostic pages 9-12, bisceglia2024bag2mad2l1and pages 2-3, bisceglia2024bag2mad2l1and pages 1-2, lauer2024recruitmentofbag2 pages 13-17, lauer2024recruitmentofbag2 pages 1-5, lauer2024recruitmentofbag2 pages 17-21)	Yang et al., 2023, Frontiers in Aging Neuroscience, https://doi.org/10.3389/fnagi.2023.1090400 (OpenTargets Search: -BAG2); Lian et al., 2024, Scientific Reports, https://doi.org/10.1038/s41598-024-67659-6 (lian2024decipheringtheprognostic pages 9-12); Bisceglia et al., 2024, Cancer Gene Therapy, https://doi.org/10.1038/s41417-024-00805-4 (bisceglia2024bag2mad2l1and pages 2-3, bisceglia2024bag2mad2l1and pages 1-2); Liu et al., 2024, Research Square preprint, https://doi.org/10.21203/rs.3.rs-4285523/v1 (liu2024blockageofbag2chip pages 8-10); Lauer et al., 2024, bioRxiv, https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 13-17, lauer2024recruitmentofbag2 pages 1-5, lauer2024recruitmentofbag2 pages 17-21)
Applications/biomarker/therapeutics	BAG2 is being explored as a biomarker and possible therapeutic target, particularly in cancers. In mesothelioma, BAG2 overexpression by IHC may help distinguish malignant pleural mesothelioma from reactive mesothelial proliferation. In liposarcoma, high BAG2 contributed to a 2-gene risk signature with BAG1. In gastric cancer, the BAG2–CHIP interaction was proposed as a druggable axis, with FIIN-2 reported as a small-molecule inhibitor of the BAG2–CHIP complex in preclinical models. In fibrolamellar carcinoma, BAG2 was proposed as a progression biomarker and chemoresistance factor linked to response to etoposide/navitoclax combinations. No approved BAG2-targeted therapies were identified in the gathered evidence. (liu2024blockageofbag2chip pages 1-5, lian2024decipheringtheprognostic pages 9-12, bisceglia2024bag2mad2l1and pages 1-2, bisceglia2024bag2mad2l1and pages 9-12, lauer2024recruitmentofbag2 pages 1-5, lauer2024recruitmentofbag2 pages 21-24)	Bisceglia et al., 2024, Cancer Gene Therapy, https://doi.org/10.1038/s41417-024-00805-4 (bisceglia2024bag2mad2l1and pages 1-2, bisceglia2024bag2mad2l1and pages 9-12); Lian et al., 2024, Scientific Reports, https://doi.org/10.1038/s41598-024-67659-6 (lian2024decipheringtheprognostic pages 9-12); Liu et al., 2024, Research Square preprint, https://doi.org/10.21203/rs.3.rs-4285523/v1 (liu2024blockageofbag2chip pages 1-5); Lauer et al., 2024, bioRxiv, https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 1-5, lauer2024recruitmentofbag2 pages 21-24)
Quantitative data highlights	Mesothelioma: independent RNA-seq validation cohort n=211; BAG2 upregulated with baseMean 1405.02, log2FC 1.55, lfcSE 0.45, stat 3.47, padj 0.0019; separate tissue cohort n=40 and BAG2 IHC showed moderate/strong staining in MPM but not RMP. Gastric cancer: TCGA RNA analysis n=392 and tissue microarray n=152 paired tumors/adjacent tissues showed BAG2 overexpression associated with poorer prognosis; BAG2 knockout reduced tumor growth and increased apoptotic markers. Fibrolamellar carcinoma: proximity proteomics identified 1,174 proteins with 261 significant interactors; combined etoposide+navitoclax reduced viability in AML12 DNAJ-PKAc cells to 0.450 ± 0.042 versus etoposide and 0.163 ± 0.012 versus vehicle (SEM, n=3). Liposarcoma: BAG2 correlated negatively with PPARG (r=-0.63, p<2.2×10−16) and positively with NFKB1 (r=0.5, p=3.1×10−10). (lian2024decipheringtheprognostic pages 9-12, liu2024blockageofbag2chip pages 8-10, bisceglia2024bag2mad2l1and pages 2-3, bisceglia2024bag2mad2l1and pages 9-12, lauer2024recruitmentofbag2 pages 17-21, lauer2024recruitmentofbag2 pages 5-9)	Bisceglia et al., 2024, Cancer Gene Therapy, https://doi.org/10.1038/s41417-024-00805-4 (bisceglia2024bag2mad2l1and pages 2-3, bisceglia2024bag2mad2l1and pages 9-12); Liu et al., 2024, Research Square preprint, https://doi.org/10.21203/rs.3.rs-4285523/v1 (liu2024blockageofbag2chip pages 8-10); Lauer et al., 2024, bioRxiv, https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 17-21, lauer2024recruitmentofbag2 pages 5-9); Lian et al., 2024, Scientific Reports, https://doi.org/10.1038/s41598-024-67659-6 (lian2024decipheringtheprognostic pages 9-12)

Table: This table summarizes the experimentally supported functional annotation of human BAG2, emphasizing its co-chaperone role in HSP70/HSC70–CHIP proteostasis networks, disease-linked 2023–2024 findings, and quantitative highlights. It is useful as a compact evidence map for identity, mechanism, pathways, localization limits, and translational relevance.

10) Notes on scope limits of the retrieved evidence

Tau/APP mechanistic biochemistry: This run retrieved AD-related BAG2 association mainly through expression/network modeling rather than direct biochemical demonstration of BAG2 acting on tau/APP. (OpenTargets Search: -BAG2)
Subcellular localization: The retrieved excerpts support BAG2 participation in large intracellular complexes and Hsp70-dependent scaffolds but do not definitively map BAG2 to a single subcellular compartment under basal conditions. (arndt2005bag2actsas pages 3-5, lauer2024recruitmentofbag2 pages 17-21)

11) Key references (URLs and publication dates)

Arndt V. et al. “BAG-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase CHIP.” Molecular Biology of the Cell (Dec 2005). https://doi.org/10.1091/mbc.e05-07-0660 (arndt2005bag2actsas pages 3-5)
Schönbühler B. et al. “BAG2 Interferes with CHIP-Mediated Ubiquitination of HSP72.” International Journal of Molecular Sciences (Dec 2016). https://doi.org/10.3390/ijms18010069 (schonbuhler2016bag2interfereswith pages 1-3)
Yang X. et al. “The relationship between protein modified folding molecular network and Alzheimer’s disease pathogenesis…” Frontiers in Aging Neuroscience (May 2023). https://doi.org/10.3389/fnagi.2023.1090400 (OpenTargets Search: -BAG2)
Bisceglia L. et al. “BAG2, MAD2L1, and MDK are cancer-driver genes…” Cancer Gene Therapy (Sep 2024). https://doi.org/10.1038/s41417-024-00805-4 (bisceglia2024bag2mad2l1and pages 2-3)
Lian Y. et al. “Deciphering the prognostic and therapeutic significance of BAG1 and BAG2…” Scientific Reports (Oct 2024). https://doi.org/10.1038/s41598-024-67659-6 (lian2024decipheringtheprognostic pages 9-12)
Lauer S.M. et al. “Recruitment of BAG2 to DNAJ-PKAc scaffolds…” bioRxiv (Jun 2024, preprint). https://doi.org/10.1101/2023.06.28.546958 (lauer2024recruitmentofbag2 pages 17-21)
Liu Q. et al. “Blockage of BAG2-CHIP Axis Combats Gastric Cancer…” Research Square (Apr 2024, preprint). https://doi.org/10.21203/rs.3.rs-4285523/v1 (liu2024blockageofbag2chip pages 1-5)

References

(arndt2005bag2actsas pages 1-2): Verena Arndt, Christina Daniel, Wolfgang Nastainczyk, Simon Alberti, and Jörg Höhfeld. Bag-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase chip. Dec 2005. URL: https://doi.org/10.1091/mbc.e05-07-0660, doi:10.1091/mbc.e05-07-0660. This article has 277 citations and is from a domain leading peer-reviewed journal.
(arndt2005bag2actsas pages 2-3): Verena Arndt, Christina Daniel, Wolfgang Nastainczyk, Simon Alberti, and Jörg Höhfeld. Bag-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase chip. Dec 2005. URL: https://doi.org/10.1091/mbc.e05-07-0660, doi:10.1091/mbc.e05-07-0660. This article has 277 citations and is from a domain leading peer-reviewed journal.
(arndt2005bag2actsas pages 3-5): Verena Arndt, Christina Daniel, Wolfgang Nastainczyk, Simon Alberti, and Jörg Höhfeld. Bag-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase chip. Dec 2005. URL: https://doi.org/10.1091/mbc.e05-07-0660, doi:10.1091/mbc.e05-07-0660. This article has 277 citations and is from a domain leading peer-reviewed journal.
(schonbuhler2016bag2interfereswith pages 1-3): Bianca Schönbühler, Verena Schmitt, Heike Huesmann, Andreas Kern, Martin Gamerdinger, and Christian Behl. Bag2 interferes with chip-mediated ubiquitination of hsp72. International Journal of Molecular Sciences, 18:69, Dec 2016. URL: https://doi.org/10.3390/ijms18010069, doi:10.3390/ijms18010069. This article has 20 citations.
(altinok2021withorwithout pages 12-13): Selin Altinok, Rebekah Sanchez-Hodge, Mariah Stewart, Kaitlan Smith, and Jonathan C. Schisler. With or without you: co-chaperones mediate health and disease by modifying chaperone function and protein triage. Cells, 10:3121, Nov 2021. URL: https://doi.org/10.3390/cells10113121, doi:10.3390/cells10113121. This article has 34 citations.
(arndt2005bag2actsas media 4ec539ab): Verena Arndt, Christina Daniel, Wolfgang Nastainczyk, Simon Alberti, and Jörg Höhfeld. Bag-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase chip. Dec 2005. URL: https://doi.org/10.1091/mbc.e05-07-0660, doi:10.1091/mbc.e05-07-0660. This article has 277 citations and is from a domain leading peer-reviewed journal.
(schonbuhler2016bag2interfereswith pages 3-6): Bianca Schönbühler, Verena Schmitt, Heike Huesmann, Andreas Kern, Martin Gamerdinger, and Christian Behl. Bag2 interferes with chip-mediated ubiquitination of hsp72. International Journal of Molecular Sciences, 18:69, Dec 2016. URL: https://doi.org/10.3390/ijms18010069, doi:10.3390/ijms18010069. This article has 20 citations.
(schonbuhler2016bag2interfereswith pages 6-8): Bianca Schönbühler, Verena Schmitt, Heike Huesmann, Andreas Kern, Martin Gamerdinger, and Christian Behl. Bag2 interferes with chip-mediated ubiquitination of hsp72. International Journal of Molecular Sciences, 18:69, Dec 2016. URL: https://doi.org/10.3390/ijms18010069, doi:10.3390/ijms18010069. This article has 20 citations.
(arndt2005bag2actsas media 2bb89edf): Verena Arndt, Christina Daniel, Wolfgang Nastainczyk, Simon Alberti, and Jörg Höhfeld. Bag-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase chip. Dec 2005. URL: https://doi.org/10.1091/mbc.e05-07-0660, doi:10.1091/mbc.e05-07-0660. This article has 277 citations and is from a domain leading peer-reviewed journal.
(lauer2024recruitmentofbag2 pages 5-9): Sophia M Lauer, Mitchell H Omar, Martin G Golkowski, Heidi L Kenerson, Bryan C Pascual, Katherine Forbush, F Donelson Smith, John Gordan, Shao-En Ong, Raymond S Yeung, and John D Scott. Recruitment of bag2 to dnaj-pkac scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2023.06.28.546958, doi:10.1101/2023.06.28.546958. This article has 21 citations.
(lauer2024recruitmentofbag2 pages 17-21): Sophia M Lauer, Mitchell H Omar, Martin G Golkowski, Heidi L Kenerson, Bryan C Pascual, Katherine Forbush, F Donelson Smith, John Gordan, Shao-En Ong, Raymond S Yeung, and John D Scott. Recruitment of bag2 to dnaj-pkac scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2023.06.28.546958, doi:10.1101/2023.06.28.546958. This article has 21 citations.
(liu2024blockageofbag2chip pages 1-5): Qian Liu, Hong Wei, Baoyuan Tang, Binbin Tian, Zhijian Ma, Qianlin Gu, Xiaolu Su, Zeyuan Yu, Yuman Dong, Wengui Shi, and Changjiang Luo. Blockage of bag2-chip axis combats gastric cancer by inducing hsp70 ubiquitination-mediated apoptosis. Unknown journal, Apr 2024. URL: https://doi.org/10.21203/rs.3.rs-4285523/v1, doi:10.21203/rs.3.rs-4285523/v1.
(liu2024blockageofbag2chip pages 8-10): Qian Liu, Hong Wei, Baoyuan Tang, Binbin Tian, Zhijian Ma, Qianlin Gu, Xiaolu Su, Zeyuan Yu, Yuman Dong, Wengui Shi, and Changjiang Luo. Blockage of bag2-chip axis combats gastric cancer by inducing hsp70 ubiquitination-mediated apoptosis. Unknown journal, Apr 2024. URL: https://doi.org/10.21203/rs.3.rs-4285523/v1, doi:10.21203/rs.3.rs-4285523/v1.
(OpenTargets Search: -BAG2): Open Targets Query (-BAG2, 5 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.
(bisceglia2024bag2mad2l1and pages 2-3): Luisa Bisceglia, Federica Morani, Lara Guerrieri, Eric Santoni-Rugiu, Pınar Çakılkaya, Cristian Scatena, Rosa Scarpitta, Lars H. Engelholm, Niels Behrendt, Federica Gemignani, and Stefano Landi. Bag2, mad2l1, and mdk are cancer-driver genes and candidate targets for novel therapies in malignant pleural mesothelioma. Cancer Gene Therapy, 31:1708-1720, Sep 2024. URL: https://doi.org/10.1038/s41417-024-00805-4, doi:10.1038/s41417-024-00805-4. This article has 1 citations and is from a peer-reviewed journal.
(bisceglia2024bag2mad2l1and pages 1-2): Luisa Bisceglia, Federica Morani, Lara Guerrieri, Eric Santoni-Rugiu, Pınar Çakılkaya, Cristian Scatena, Rosa Scarpitta, Lars H. Engelholm, Niels Behrendt, Federica Gemignani, and Stefano Landi. Bag2, mad2l1, and mdk are cancer-driver genes and candidate targets for novel therapies in malignant pleural mesothelioma. Cancer Gene Therapy, 31:1708-1720, Sep 2024. URL: https://doi.org/10.1038/s41417-024-00805-4, doi:10.1038/s41417-024-00805-4. This article has 1 citations and is from a peer-reviewed journal.
(bisceglia2024bag2mad2l1and pages 9-12): Luisa Bisceglia, Federica Morani, Lara Guerrieri, Eric Santoni-Rugiu, Pınar Çakılkaya, Cristian Scatena, Rosa Scarpitta, Lars H. Engelholm, Niels Behrendt, Federica Gemignani, and Stefano Landi. Bag2, mad2l1, and mdk are cancer-driver genes and candidate targets for novel therapies in malignant pleural mesothelioma. Cancer Gene Therapy, 31:1708-1720, Sep 2024. URL: https://doi.org/10.1038/s41417-024-00805-4, doi:10.1038/s41417-024-00805-4. This article has 1 citations and is from a peer-reviewed journal.
(lian2024decipheringtheprognostic pages 9-12): Yingying Lian, Jiahao Chen, Jiayang Han, Binbin Zhao, Jialin Wu, Xinyu Li, Man Yue, Mengwen Hou, Tinggai Wu, Ting Ye, Xu Han, Tiantian Sun, Mengjie Tu, Kaifeng Zhang, Guangchao Liu, and Yang An. Deciphering the prognostic and therapeutic significance of bag1 and bag2 for predicting distinct survival outcome and effects on liposarcoma. Scientific Reports, Oct 2024. URL: https://doi.org/10.1038/s41598-024-67659-6, doi:10.1038/s41598-024-67659-6. This article has 0 citations and is from a peer-reviewed journal.
(lauer2024recruitmentofbag2 pages 13-17): Sophia M Lauer, Mitchell H Omar, Martin G Golkowski, Heidi L Kenerson, Bryan C Pascual, Katherine Forbush, F Donelson Smith, John Gordan, Shao-En Ong, Raymond S Yeung, and John D Scott. Recruitment of bag2 to dnaj-pkac scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2023.06.28.546958, doi:10.1101/2023.06.28.546958. This article has 21 citations.
(heymann2019cterminusofhsp70 pages 24-27): GS Heymann. C-terminus of hsp70 interacting protein as a regulator of parkin translocation. Unknown journal, 2019.
(lauer2024recruitmentofbag2 pages 1-5): Sophia M Lauer, Mitchell H Omar, Martin G Golkowski, Heidi L Kenerson, Bryan C Pascual, Katherine Forbush, F Donelson Smith, John Gordan, Shao-En Ong, Raymond S Yeung, and John D Scott. Recruitment of bag2 to dnaj-pkac scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2023.06.28.546958, doi:10.1101/2023.06.28.546958. This article has 21 citations.
(lauer2024recruitmentofbag2 pages 21-24): Sophia M Lauer, Mitchell H Omar, Martin G Golkowski, Heidi L Kenerson, Bryan C Pascual, Katherine Forbush, F Donelson Smith, John Gordan, Shao-En Ong, Raymond S Yeung, and John D Scott. Recruitment of bag2 to dnaj-pkac scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2023.06.28.546958, doi:10.1101/2023.06.28.546958. This article has 21 citations.

Artifacts

Edison artifact artifact-00

Citations

lian2024decipheringtheprognostic pages 9-12
altinok2021withorwithout pages 12-13
https://doi.org/10.1091/mbc.e05-07-0660
https://doi.org/10.3390/ijms18010069
https://doi.org/10.3390/cells10113121
https://doi.org/10.21203/rs.3.rs-4285523/v1
https://doi.org/10.1101/2023.06.28.546958
https://doi.org/10.3389/fnagi.2023.1090400
https://doi.org/10.1038/s41598-024-67659-6
https://doi.org/10.1038/s41417-024-00805-4
https://doi.org/10.1091/mbc.e05-07-0660,
https://doi.org/10.3390/ijms18010069,
https://doi.org/10.3390/cells10113121,
https://doi.org/10.1101/2023.06.28.546958,
https://doi.org/10.21203/rs.3.rs-4285523/v1,
https://doi.org/10.1038/s41417-024-00805-4,
https://doi.org/10.1038/s41598-024-67659-6,

📚 Additional Documentation

Notes

(BAG2-notes.md)

BAG2 (O95816) research notes

Identity / domain architecture

BAG family molecular chaperone regulator 2 (BAG-2 / Bcl-2-associated athanogene 2). 211 aa. Single BAG domain (residues 109-189) and an N-terminal coiled coil (20-61). [file:human/BAG2/BAG2-uniprot.txt "DOMAIN 109..189"]
Unlike BAG1, BAG2 lacks a ubiquitin-like (UBL) domain. PMID:19228967

Core molecular function: HSP70/HSC70 nucleotide-exchange factor (co-chaperone)

BAG2 is a co-chaperone for HSP70/HSC70, acting as a nucleotide-exchange factor (NEF) that promotes ADP release and thereby client release. [file:human/BAG2/BAG2-uniprot.txt "Acts as\nCC a nucleotide-exchange factor (NEF) promoting the release of ADP from"]
Member of an evolutionarily conserved family of Hsp70/Hsc70 regulators; binds with high affinity (KD ~1-10 nM) to the ATPase domain of Hsc70 and modulates chaperone activity in a Hip-repressible manner. PMID:9873016
Direct biochemical confirmation of NEF / Hsp70-binding activity: BAG2 binds Hsp72 (HSPA1A) and acts in nucleotide/peptide release assays (though with notably lower affinity than BAG1/BAG3). PMID:24318877 PMID:24318877

CHIP (STUB1) E3 ligase inhibition / protein triage

BAG2 is a main component of CHIP complexes and inhibits CHIP ubiquitin ligase activity by abrogating the CHIP/E2 cooperation. PMID:16207813
This is a negative regulation of ubiquitination of chaperone clients; BAG2 stimulates CFTR maturation (a transmembrane transporter client). PMID:16207813
BAG2 stabilizes immature CFTR conformations in addition to inhibiting CHIP. PMID:16207813
BAG2 interacts with STUB1 (CHIP) per UniProt interaction table. [file:human/BAG2/BAG2-uniprot.txt "Q9UNE7: STUB1"]

Tau triage at the microtubule (neuronal context)

The BAG2/Hsp70 complex is tethered to the microtubule and captures/delivers tau to the proteasome for ubiquitin-independent degradation; preferentially degrades Sarkosyl-insoluble and phosphorylated tau. PMID:19228967
BAG2 can associate with microtubules even without tau. PMID:19228967
By inhibiting CHIP, BAG2 directs the Hsp70-tau complex away from ubiquitination. PMID:19228967
This pathway is ubiquitin-INDEPENDENT and proteasome-dependent. PMID:19228967
NOTE on the negated annotation GO:0032436 (positive regulation of proteasomal ubiquitin-dependent protein catabolic process, NOT): consistent with BAG2 routing tau to a ubiquitin-INDEPENDENT proteasomal route while inhibiting the ubiquitin-dependent CHIP route. The NOT is well justified.

Substrate stabilization by reducing ubiquitination (disease-relevant clients)

BAG2 directly binds and stabilizes PINK1 by decreasing its ubiquitination. PMID:24383081
BAG2 (with BAG5) stabilizes pathogenic ataxin3-80Q by inhibiting its ubiquitination. PMID:25006867

Localization

Cytosolic (Reactome TAS). Neuronal axon/dendrite/(dendritic) microtubule colocalization annotations derive from ARUK-UCL ISS based on the tau-triage microtubule work (PMID:19228967), which demonstrated microtubule tethering. These are real but context-specific (neuronal) localizations.

Synthesis of core vs non-core

CORE: HSP70/HSC70 nucleotide-exchange factor activity (GO:0000774), heat shock protein / chaperone binding, co-chaperone in a protein-folding chaperone complex, negative regulation of CHIP-mediated protein ubiquitination (GO:0031397), protein stabilization (GO:0050821) of chaperone clients.
NON-CORE / context: tau binding & neuronal microtubule/axon/dendrite localization (neuronal protein-triage context); CFTR (transmembrane transporter) maturation.
OVER-ANNOTATED / uninformative: the many high-throughput "protein binding" (GO:0005515) IPI annotations from interactome maps (spliceosome, viral perturbation, histone crosslinking, EGFR network, kinase networks, OpenCell, etc.).
Broad/indirect BP terms (positive regulation of protein metabolic process GO:0051247; protein metabolic process GO:0019538) are over-broad parent terms.

Falcon deep research findings (2026-06-07)

Synthesis of the new Falcon (Edison) report relative to the existing COMPLETE review. CONFIRMS = already in review; NEW = not previously captured; PROVISIONAL = preprint/low-confidence, not used to change annotations.

CONFIRMS (core mechanism): BAG2 is a BAG-family HSP70/HSC70 co-chaperone/NEF that binds the chaperone ATPase domain via its C-terminal BAG domain and inhibits CHIP/STUB1 E3 ligase by disrupting CHIP-E2 (UBCH5A/B) cooperation, shifting protein triage away from ubiquitination/degradation. The foundational Arndt 2005 biochemistry (BAG2 inhibits CHIP-mediated ubiquitylation of Raf-1 and Hsc70; co-fractionates with Hsc70/CHIP in high-MW complexes) underpins the already-cited Dai/PMID:16207813 work. [DOI:10.1091/mbc.e05-07-0660 Arndt 2005 "BAG-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase CHIP"]
NEW (peer-reviewed, added to refs): Schönbühler 2016 shows BAG2 prevents CHIP-mediated ubiquitination of HSP72 (HSPA1A/HSPA1B) and stabilizes HSP72 post-translationally (no mRNA change); BAG2 and CHIP protein levels rise in senescent fibroblasts (aging-associated proteostasis). [DOI:10.3390/ijms18010069 Schönbühler 2016]. NOTE: this DOI did not reliably resolve to a PubMed PMID via E-utilities, so kept in notes only, not added to refs.
NEW (peer-reviewed, added to refs): Altinok 2021 review frames BAG2 as a co-chaperone that modifies chaperone function and protein triage in health/disease. PMID:34831344
NEW (peer-reviewed, added to refs): Bisceglia 2024 identifies BAG2 as a candidate cancer-driver/diagnostic-adjunct in malignant pleural mesothelioma (upregulated by RNA-seq log2FC 1.55, padj 0.0019, n=211 validation cohort; moderate-strong IHC in MPM, absent in reactive mesothelium). Disease-association, not a new molecular function. PMID:39300217
PROVISIONAL (preprints / low-confidence, NOT used to change annotations): (i) Lauer 2024 bioRxiv - BAG2 recruited Hsp70-dependently to DNAJ-PKAc fusion scaffolds in fibrolamellar carcinoma, promoting survival/etoposide resistance; reported Ser20 phosphorylation. [DOI:10.1101/2023.06.28.546958]. (ii) Liu 2024 Research Square - proposed BAG2-CHIP-HSP70-Apaf1-cytochrome c anti-apoptotic axis in gastric cancer; FIIN-2 proposed as BAG2-CHIP inhibitor. [DOI:10.21203/rs.3.rs-4285523/v1]. (iii) Lian 2024 - BAG2 prognostic associations in liposarcoma. [DOI:10.1038/s41598-024-67659-6]. (iv) Yang 2023 - AD network modeling links a BAG2-HSC70-STUB1-MAPT expression signature to disease (expression/network only, not biochemical). [DOI:10.3389/fnagi.2023.1090400]. These reinforce the existing "tunable brake on CHIP/STUB1 ubiquitination -> pro-survival/chemoresistance" theme but add no validated new GO molecular function or localization.
LOCALIZATION (status unchanged): Report supports BAG2 in large cytosolic high-MW Hsc70/CHIP complexes but does not resolve a definitive basal subcellular compartment beyond cytosol; consistent with existing cytosol (core) + neuronal microtubule/axon/dendrite (non-core) annotations. No autophagy/mitophagy or innate-immunity BAG2-specific evidence was found (explicitly flagged as not established in the report).

Pn Notes

(BAG2-pn-notes.md)

BAG2 PN Consistency Notes

Generated: 2026-06-18
Project: PROTEOSTASIS
Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
UniProt: O95816
AIGR review status: COMPLETE
Review batch: proteostasis-batch-2026-06-06
Batch change status: added

Source Files Checked

AIGR review YAML: present - genes/human/BAG2/BAG2-ai-review.yaml
AIGR review HTML: present - genes/human/BAG2/BAG2-ai-review.html
Gene notes: present - genes/human/BAG2/BAG2-notes.md
GOA TSV: present - genes/human/BAG2/BAG2-goa.tsv
UniProt record: present - genes/human/BAG2/BAG2-uniprot.txt
PN dossier: projects/PROTEOSTASIS/reports/phase1_dossiers/BAG2.md
PN consistency section: projects/PROTEOSTASIS/reports/phase1_dossiers/_sections/BAG2.md
PN projection report: projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
PN mapping audit: projects/PROTEOSTASIS/reports/pn_mapping_audit/current_mapping_scrutiny.tsv

Deep Research Files

genes/human/BAG2/BAG2-deep-research-falcon.md

AIGR Review Snapshot

Description: BAG2 (BAG family molecular chaperone regulator 2) is a cytosolic co-chaperone of the HSP70/HSC70 molecular chaperone system. Through its C-terminal BAG domain it binds the ATPase (nucleotide-binding) domain of HSP70/HSC70 and acts as a nucleotide-exchange factor (NEF), promoting ADP release and consequent release of bound client/substrate proteins, thereby regulating the HSP70 chaperone cycle. BAG2 is a major component of complexes containing the chaperone-associated E3 ubiquitin ligase CHIP (STUB1) and inhibits CHIP ligase activity by disrupting cooperation between CHIP and its E2 enzyme, so that BAG2 reduces ubiquitination of chaperone clients and shifts protein triage away from degradation toward folding/maturation and stabilization. In neurons, the BAG2/HSP70 complex is tethered to microtubules and captures misfolded, phosphorylated, detergent-insoluble tau, delivering it for ubiquitin-independent proteasomal degradation. BAG2 also binds and stabilizes specific clients (e.g., CFTR, PINK1, polyglutamine-expanded ataxin-3) by lowering their ubiquitination. Unlike BAG1, BAG2 lacks a ubiquitin-like domain. Its core roles are HSP70 nucleotide exchange, chaperone-assisted protein quality control, and negative regulation of CHIP-dependent client ubiquitination.
Existing/core annotation action counts: ACCEPT: 20; KEEP_AS_NON_CORE: 17; MARK_AS_OVER_ANNOTATED: 24; REMOVE: 1

PN Consistency Summary

Consistency: Row 1 fully consistent. Review, notes and Falcon deep research converge on BAG2 as an HSP70/HSC70 nucleotide-exchange factor (BAG domain) that inhibits CHIP/STUB1 E3 ligase and stabilizes clients (PMID:24318877, 16207813, 24383081, 25006867). GO:0000774 is the accepted core MF (verified real) and is ACCEPT in the review. Row 2 (proteasome adaptor → proteasome binding) is NOT supported: BAG2 acts on HSP70 and on the E3 CHIP, not on the 26S proteasome; neither review nor deep research reports direct proteasome binding. The tau pathway delivers tau "to the proteasome" but via HSP70, not by BAG2 binding the proteasome.
PN story / NEW pressure: Row 1 already captured (GO:0000774 ACCEPT). Row 2 GO:0070628 proteasome binding (verified real term) is flagged new_to_goa, but it is an over-reach for BAG2 — no evidence BAG2 directly binds the proteasome. The better-supported UPS-side functions (ubiquitin protein ligase binding GO:0031625, negative regulation of ubiquitination GO:0031397) are already ACCEPT in the review. Conclusion: row 1 already captured; row 2 proteasome-binding projection over-reaches.
Evidence alignment: PN cites no row-level references. Review/deep-research PMIDs (Arndt 2005=PMID:16207813, 24318877, 19228967, 24383081, 25006867) all concern HSP70/CHIP/client biology, none proteasome binding — divergent from the row-2 projection.
Verdict: NEF classification sound and already captured; the UPS "adaptor → proteasome binding" projection is unsupported for BAG2. Recommended edits: [MAP] do not project GO:0070628 proteasome binding onto O95816 (BAG2 binds HSP70 and CHIP, not the proteasome); its UPS role is already covered by GO:0031625 / GO:0031397 in the review.

Full Consistency Review

UniProt: O95816 · batch: proteostasis-batch-2026-06-06 · review status: COMPLETE
PN placement: two rows — Cytonuclear proteostasis|Chaperone|HSP70 system|HSP70 nucleotide exchange factor|BAG domain subtype and Ubiquitin Proteasome System|Proteasome and associated proteins|adaptors|BAG ; PN-node mapping: NEF type → mapped/ok GO:0000774 (already_in_goa_exact); UPS adaptors group → mapped/ok GO:0070628 proteasome binding (new_to_goa); proteasome class → context_only/too_broad GO:0000502.
Consistency: Row 1 fully consistent. Review, notes and Falcon deep research converge on BAG2 as an HSP70/HSC70 nucleotide-exchange factor (BAG domain) that inhibits CHIP/STUB1 E3 ligase and stabilizes clients (PMID:24318877, 16207813, 24383081, 25006867). GO:0000774 is the accepted core MF (verified real) and is ACCEPT in the review. Row 2 (proteasome adaptor → proteasome binding) is NOT supported: BAG2 acts on HSP70 and on the E3 CHIP, not on the 26S proteasome; neither review nor deep research reports direct proteasome binding. The tau pathway delivers tau "to the proteasome" but via HSP70, not by BAG2 binding the proteasome.
PN story / NEW pressure: Row 1 already captured (GO:0000774 ACCEPT). Row 2 GO:0070628 proteasome binding (verified real term) is flagged new_to_goa, but it is an over-reach for BAG2 — no evidence BAG2 directly binds the proteasome. The better-supported UPS-side functions (ubiquitin protein ligase binding GO:0031625, negative regulation of ubiquitination GO:0031397) are already ACCEPT in the review. Conclusion: row 1 already captured; row 2 proteasome-binding projection over-reaches.
Mapping strategy: Row-1 NEF mapping needs no change (exact match). Row-2 "proteasome binding" should NOT project onto BAG2; if the adaptors group genuinely shares proteasome binding, BAG2 is the exception (it is a chaperone/E3-adaptor, not a proteasome shuttle like the UBL-UBA family).
Evidence alignment: PN cites no row-level references. Review/deep-research PMIDs (Arndt 2005=PMID:16207813, 24318877, 19228967, 24383081, 25006867) all concern HSP70/CHIP/client biology, none proteasome binding — divergent from the row-2 projection.
Verdict: NEF classification sound and already captured; the UPS "adaptor → proteasome binding" projection is unsupported for BAG2. Recommended edits: [MAP] do not project GO:0070628 proteasome binding onto O95816 (BAG2 binds HSP70 and CHIP, not the proteasome); its UPS role is already covered by GO:0031625 / GO:0031397 in the review.

PN Dossier Context

review_batch: proteostasis-batch-2026-06-06
review_yaml: genes/human/BAG2/BAG2-ai-review.yaml
PN workbook rows: 2

PN row 1: Cytonuclear proteostasis | Chaperone | HSP70 system | HSP70 nucleotide exchange factor | BAG domain subtype

UniProt: O95816
In branches: CY, UPS
PN-node mapping records (path + ancestors):
- [subtype] Cytonuclear proteostasis|Chaperone|HSP70 system|HSP70 nucleotide exchange factor|BAG domain subtype
  status=no_mapping scope= GO=[]
  rationale: Reviewed as a narrower taxonomy bucket that is already covered by a curated parent mapping or by gene-level annotations. No additional direct GO mapping is appropriate from this node.
- [type] Cytonuclear proteostasis|Chaperone|HSP70 system|HSP70 nucleotide exchange factor
  status=mapped scope=ok_for_propagation_to_go GO=[GO:0000774 adenyl-nucleotide exchange factor activity]
  rationale: These PN entries denote nucleotide exchange factors that reset HSP70 chaperones by promoting ADP release. The current validated GO cache does not expose a more HSP70-specific exchange-factor term, so adenyl-nucleotide exchange factor activity is the best supported target.
- [group] Cytonuclear 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] Cytonuclear proteostasis|Chaperone
  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.
- [branch] Cytonuclear 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.

PN row 2: Ubiquitin Proteasome System | Proteasome and associated proteins | adaptors | BAG

UniProt: O95816
In branches: CY, UPS
Signature domains: IPR037689
Auxiliary domains: IPR003103, IPR037689
PN-node mapping records (path + ancestors):
- [type] Ubiquitin Proteasome System|Proteasome and associated proteins|adaptors|BAG
  status=no_mapping scope= GO=[]
  rationale: Reviewed as a narrower proteasome component, chaperone, adaptor, domain, or isoform subdivision already covered by a curated parent proteasome mapping. No additional direct GO mapping is needed at this node.
- [group] Ubiquitin Proteasome System|Proteasome and associated proteins|adaptors
  status=mapped scope=ok_for_propagation_to_go GO=[GO:0070628 proteasome binding]
  rationale: This PN group captures proteasome adaptors and shuttle factors. Proteasome binding is the safe shared molecular-function target.
- [class] Ubiquitin Proteasome System|Proteasome and associated proteins
  status=context_only scope=too_broad_to_propagate GO=[GO:0000502 proteasome complex]
  rationale: This class records the proteasome branch context, but descendants include core and regulatory particle subunits, activators, assembly chaperones, adaptors, DUBs, E3 ligases, enzymes, and transcriptional regulators. Propagation should come from narrower nodes.
- [branch] Ubiquitin Proteasome System
  status=no_mapping scope= GO=[]
  rationale: Reviewed as the top-level UPS branch. It is a project taxonomy umbrella rather than a direct GO assertion; UPS propagation must come from manually curated child nodes.

Projected GO annotations (2)

GO:0000774 adenyl-nucleotide exchange factor activity | scope=ok_for_propagation_to_go | goa_status=already_in_goa_exact | from=Cytonuclear proteostasis|Chaperone|HSP70 system|HSP70 nucleotide exchange factor
GO:0070628 proteasome binding | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=Ubiquitin Proteasome System|Proteasome and associated proteins|adaptors

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: O95816
gene_symbol: BAG2
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: 'BAG2 (BAG family molecular chaperone regulator 2) is a cytosolic co-chaperone
  of the HSP70/HSC70 molecular chaperone system. Through its C-terminal BAG domain it
  binds the ATPase (nucleotide-binding) domain of HSP70/HSC70 and acts as a nucleotide-exchange
  factor (NEF), promoting ADP release and consequent release of bound client/substrate
  proteins, thereby regulating the HSP70 chaperone cycle. BAG2 is a major component of
  complexes containing the chaperone-associated E3 ubiquitin ligase CHIP (STUB1) and
  inhibits CHIP ligase activity by disrupting cooperation between CHIP and its E2 enzyme,
  so that BAG2 reduces ubiquitination of chaperone clients and shifts protein triage
  away from degradation toward folding/maturation and stabilization. In neurons, the
  BAG2/HSP70 complex is tethered to microtubules and captures misfolded, phosphorylated,
  detergent-insoluble tau, delivering it for ubiquitin-independent proteasomal degradation.
  BAG2 also binds and stabilizes specific clients (e.g., CFTR, PINK1, polyglutamine-expanded
  ataxin-3) by lowering their ubiquitination. Unlike BAG1, BAG2 lacks a ubiquitin-like
  domain. Its core roles are HSP70 nucleotide exchange, chaperone-assisted protein
  quality control, and negative regulation of CHIP-dependent client ubiquitination.'
alternative_products:
- name: '1'
  id: O95816-1
- name: '2'
  id: O95816-2
  sequence_note: VSP_056462
existing_annotations:
- term:
    id: GO:0000774
    label: adenyl-nucleotide exchange factor activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: BAG2 is a nucleotide-exchange factor (NEF) for HSP70/HSC70, promoting ADP
      release via its BAG domain. This is the core molecular function and is well supported
      experimentally.
    action: ACCEPT
    reason: NEF activity toward HSP70/HSC70 is the defining, experimentally validated
      molecular function of BAG2 and is consistent with the phylogenetic inference.
    supported_by:
    - reference_id: file:human/BAG2/BAG2-uniprot.txt
      supporting_text: a nucleotide-exchange factor (NEF) promoting the release of ADP from
      reference_section_type: DATABASE_ENTRY
    - reference_id: PMID:24318877
      supporting_text: Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide
        exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).
      reference_section_type: ABSTRACT
- term:
    id: GO:0050821
    label: protein stabilization
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: BAG2 stabilizes specific chaperone clients (CFTR, PINK1, ataxin-3) by
      reducing their ubiquitination, so protein stabilization is a supported core process.
    action: ACCEPT
    reason: BAG2 lowers ubiquitination of clients such as PINK1 and pathogenic ataxin-3,
      stabilizing them, and stabilizes immature CFTR conformations. This is a well-supported
      outcome of BAG2 co-chaperone/CHIP-inhibitory activity.
    supported_by:
    - reference_id: PMID:24383081
      supporting_text: which directly binds with and stabilises PINK1 by decreasing its
        ubiquitination
      reference_section_type: ABSTRACT
    - reference_id: PMID:25006867
      supporting_text: stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
      reference_section_type: ABSTRACT
- term:
    id: GO:0000774
    label: adenyl-nucleotide exchange factor activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: NEF activity for HSP70/HSC70 is the defining molecular function of BAG2,
      well supported experimentally and consistent with the InterPro/BAG-domain inference.
    action: ACCEPT
    reason: The BAG domain confers nucleotide-exchange activity on HSP70/HSC70; this IEA
      annotation agrees with direct biochemical evidence.
    supported_by:
    - reference_id: file:human/BAG2/BAG2-uniprot.txt
      supporting_text: a nucleotide-exchange factor (NEF) promoting the release of ADP from
      reference_section_type: DATABASE_ENTRY
    - reference_id: PMID:24318877
      supporting_text: Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide
        exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).
      reference_section_type: ABSTRACT
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: As an HSP70/HSC70 co-chaperone that regulates the chaperone cycle and can
      display intrinsic client-stabilizing activity, BAG2 participates in protein folding/refolding.
    action: ACCEPT
    reason: BAG2 modulates HSP70/HSC70 chaperone activity and contributes to chaperone-assisted
      folding/maturation of clients (e.g., CFTR), supporting the protein folding process.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: stimulates the chaperone-assisted maturation of CFTR
      reference_section_type: ABSTRACT
- term:
    id: GO:0051087
    label: protein-folding chaperone binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: BAG2 binds the ATPase domain of HSP70/HSC70 chaperones; chaperone binding is
      a core molecular feature underlying its co-chaperone/NEF role.
    action: ACCEPT
    reason: Direct binding of BAG2 to the HSP/HSC70 ATPase domain is well established and
      is the basis of its NEF activity.
    supported_by:
    - reference_id: file:human/BAG2/BAG2-uniprot.txt
      supporting_text: Binds to the ATPase domain of HSP/HSC70 chaperones
      reference_section_type: DATABASE_ENTRY
    - reference_id: PMID:9873016
      supporting_text: bind with high affinity (KD congruent with 1-10
      reference_section_type: ABSTRACT
- term:
    id: GO:0051247
    label: positive regulation of protein metabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: This is an over-broad parent process term. BAG2's effects on protein metabolism
      are better captured by specific terms (protein stabilization, protein folding,
      negative regulation of ubiquitination).
    action: MARK_AS_OVER_ANNOTATED
    reason: positive regulation of protein metabolic process is too general to convey BAG2
      function and duplicates more specific accepted terms.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18457437
  qualifier: enables
  review:
    summary: Generic high-throughput interactome/affinity-purification protein-binding
      annotation (EBNA5 TAP-MS); uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a proteomic screen does not identify a physiologically
      interpretable BAG2 molecular function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22365833
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a spliceosome interaction-mapping
      study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22810586
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a tumour-virus host network
      perturbation screen; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24510904
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from an LRRK2 interactor screen;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24981860
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a chromatin protein-interaction
      study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25036637
  qualifier: enables
  review:
    summary: From a quantitative chaperone interaction network; the relevant BAG2 biology
      (HSP70 co-chaperone binding) is captured by specific chaperone-binding terms, so
      bare protein binding is uninformative here.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding is too general; chaperone-network membership is better
      represented by protein-folding chaperone binding/complex terms.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25852190
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a TRAIL apoptosis kinase-network
      study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25959826
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a neurodegenerative-disease
      interaction proteomics study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:26496610
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a quantitative interactome study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:29513927
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a ROCO-protein interaction-network
      study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:29568061
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a MAC-tag AP-MS/BioID mapping study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:30021884
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a histone crosslinking-MS study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:31980649
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from an EGFR-network rewiring study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from the binary interactome reference map;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a neurodegenerative-disease interactome
      study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a dual proteome-scale network study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:35167623
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a DNAJB1-PRKACA signaling study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:35266954
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a TRIM1/LRRK2 study; uninformative
      for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:35271311
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from the OpenCell endogenous-tagging
      study; uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:37045861
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a RAF1-BRAF interactome study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:40205054
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a multimodal cell-map study;
      uninformative for BAG2 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding from a high-throughput interactome is not informative.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:22365833
  qualifier: enables
  review:
    summary: BAG2 self-association (homodimer) is a real biochemical property, but this
      particular annotation derives from a high-throughput spliceosome interaction map.
    action: KEEP_AS_NON_CORE
    reason: BAG2 forms homodimers, so identical protein binding is plausible, but the
      supporting study is a generic interactome screen; retain as non-core.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:25036637
  qualifier: enables
  review:
    summary: BAG2 homodimerization is consistent with biochemistry; annotation from a
      chaperone interaction-network screen.
    action: KEEP_AS_NON_CORE
    reason: Self-association is a genuine BAG2 property; retain as non-core given the
      high-throughput source.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:25416956
  qualifier: enables
  review:
    summary: BAG2 homodimerization is consistent with biochemistry; annotation from the
      proteome-scale interactome map.
    action: KEEP_AS_NON_CORE
    reason: Self-association is a genuine BAG2 property; retain as non-core given the
      high-throughput source.
- term:
    id: GO:0005874
    label: microtubule
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: colocalizes_with
  review:
    summary: The BAG2/HSP70 complex is tethered to the microtubule in neurons; microtubule
      colocalization is supported but is a context-specific (neuronal) localization.
    action: KEEP_AS_NON_CORE
    reason: Microtubule tethering is demonstrated for the tau-triage function but is a
      neuronal-context localization rather than the universal BAG2 site of action.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: The BAG2/Hsp70 complex is tethered to the microtubule
      reference_section_type: ABSTRACT
- term:
    id: GO:0030424
    label: axon
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: located_in
  review:
    summary: Neuronal compartment localization inferred from the tau-triage microtubule
      work; context-specific.
    action: KEEP_AS_NON_CORE
    reason: Axonal localization is a neuronal-context inference, not a core universal
      localization of BAG2.
- term:
    id: GO:0030425
    label: dendrite
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: located_in
  review:
    summary: Neuronal compartment localization inferred from the tau-triage microtubule
      work; context-specific.
    action: KEEP_AS_NON_CORE
    reason: Dendritic localization is a neuronal-context inference, not a core universal
      localization of BAG2.
- term:
    id: GO:0031072
    label: heat shock protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: BAG2 binds the HSP70/HSC70 chaperone ATPase domain; heat shock protein binding
      is a core molecular feature.
    action: ACCEPT
    reason: Direct binding of BAG2 to HSP/HSC70 is well established and underlies its
      co-chaperone/NEF activity.
    supported_by:
    - reference_id: file:human/BAG2/BAG2-uniprot.txt
      supporting_text: Binds to the ATPase domain of HSP/HSC70 chaperones
      reference_section_type: DATABASE_ENTRY
- term:
    id: GO:0031397
    label: negative regulation of protein ubiquitination
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: involved_in
  review:
    summary: BAG2 inhibits CHIP-mediated ubiquitination of chaperone clients; negative
      regulation of protein ubiquitination is a core process.
    action: ACCEPT
    reason: BAG2 abrogates CHIP/E2 cooperation and decreases ubiquitination of clients
      such as CFTR, PINK1, and ataxin-3.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: BAG-2 inhibits the ubiquitin ligase activity of CHIP by abrogating
        the CHIP/E2 cooperation
      reference_section_type: ABSTRACT
- term:
    id: GO:0031625
    label: ubiquitin protein ligase binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: BAG2 binds and inhibits the E3 ubiquitin ligase CHIP (STUB1); ubiquitin protein
      ligase binding is supported and mechanistically central.
    action: ACCEPT
    reason: BAG2 is a main component of CHIP complexes and binds CHIP to inhibit its ligase
      activity.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: We identified the Hsc70 cochaperone
      reference_section_type: ABSTRACT
- term:
    id: GO:0048156
    label: tau protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: BAG2 (via the BAG2/HSP70 complex) captures misfolded/insoluble tau; tau binding
      is supported in the neuronal protein-triage context.
    action: KEEP_AS_NON_CORE
    reason: Tau binding/capture is well documented but is a client-specific, neuronal-context
      activity rather than the universal BAG2 molecular function.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: this complex can capture and deliver Tau to the
      reference_section_type: ABSTRACT
- term:
    id: GO:1901588
    label: dendritic microtubule
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: colocalizes_with
  review:
    summary: Neuronal dendritic-microtubule colocalization inferred from the tau-triage
      microtubule work; context-specific.
    action: KEEP_AS_NON_CORE
    reason: Highly specific neuronal localization inference; retain as non-core.
- term:
    id: GO:1901800
    label: positive regulation of proteasomal protein catabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: In neurons BAG2/HSP70 delivers tau to the proteasome for ubiquitin-independent
      degradation, promoting proteasomal catabolism of this client.
    action: KEEP_AS_NON_CORE
    reason: Supported by the tau-triage mechanism (ubiquitin-independent proteasomal
      degradation), but it is a client/context-specific role rather than a general one.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: deliver Tau to the
      reference_section_type: ABSTRACT
- term:
    id: GO:0048156
    label: tau protein binding
  evidence_type: NAS
  original_reference_id: PMID:28386764
  qualifier: enables
  review:
    summary: Review-based assertion of BAG2-tau binding; consistent with the primary
      tau-triage data but context-specific (neuronal).
    action: KEEP_AS_NON_CORE
    reason: Tau binding is real but client/context-specific; retain as non-core.
- term:
    id: GO:0005874
    label: microtubule
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: colocalizes_with
  review:
    summary: BAG2 associates with microtubules (even without tau) in the neuronal tau-triage
      work; supported but context-specific.
    action: KEEP_AS_NON_CORE
    reason: Microtubule association is demonstrated but is a neuronal-context localization.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: The BAG2/Hsp70 complex is tethered to the microtubule
      reference_section_type: ABSTRACT
- term:
    id: GO:0030424
    label: axon
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: located_in
  review:
    summary: Neuronal axonal localization inferred from the tau-triage study; context-specific.
    action: KEEP_AS_NON_CORE
    reason: Axonal localization is a neuronal-context inference, not a core localization.
- term:
    id: GO:0030425
    label: dendrite
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: located_in
  review:
    summary: Neuronal dendritic localization inferred from the tau-triage study;
      context-specific.
    action: KEEP_AS_NON_CORE
    reason: Dendritic localization is a neuronal-context inference, not a core localization.
- term:
    id: GO:0031397
    label: negative regulation of protein ubiquitination
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: involved_in
  review:
    summary: By inhibiting CHIP, BAG2 directs the HSP70-tau complex away from ubiquitination;
      negative regulation of protein ubiquitination is core.
    action: ACCEPT
    reason: Consistent with BAG2's established CHIP-inhibitory, anti-ubiquitination role.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: BAG2 directs the Hsp70-Tau complex away from ubiquitination
      reference_section_type: DISCUSSION
- term:
    id: GO:0031397
    label: negative regulation of protein ubiquitination
  evidence_type: IDA
  original_reference_id: PMID:24383081
  qualifier: involved_in
  review:
    summary: BAG2 stabilizes PINK1 by decreasing its ubiquitination; direct support for
      negative regulation of protein ubiquitination.
    action: ACCEPT
    reason: Direct experimental demonstration that BAG2 reduces client ubiquitination.
    supported_by:
    - reference_id: PMID:24383081
      supporting_text: stabilises PINK1 by decreasing its ubiquitination
      reference_section_type: ABSTRACT
- term:
    id: GO:0031397
    label: negative regulation of protein ubiquitination
  evidence_type: IDA
  original_reference_id: PMID:25006867
  qualifier: involved_in
  review:
    summary: BAG2 inhibits ubiquitination of pathogenic ataxin-3; direct support for
      negative regulation of protein ubiquitination.
    action: ACCEPT
    reason: Direct experimental demonstration that BAG2 reduces client ubiquitination.
    supported_by:
    - reference_id: PMID:25006867
      supporting_text: stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
      reference_section_type: ABSTRACT
- term:
    id: GO:0032436
    label: positive regulation of proteasomal ubiquitin-dependent protein catabolic
      process
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: involved_in
  negated: true
  review:
    summary: The NOT annotation is well justified - BAG2 routes tau to a ubiquitin-INDEPENDENT
      proteasomal pathway while inhibiting CHIP, so it does not promote ubiquitin-dependent
      proteasomal catabolism.
    action: ACCEPT
    reason: BAG2 mediates ubiquitin-independent proteasomal degradation of tau and inhibits
      the ubiquitin-dependent CHIP route, supporting the negation.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: BAG2 mediates ubiquitin independent degradation of Tau through the
        proteasome
      reference_section_type: ABSTRACT
- term:
    id: GO:0050821
    label: protein stabilization
  evidence_type: IDA
  original_reference_id: PMID:24383081
  qualifier: involved_in
  review:
    summary: BAG2 directly stabilizes PINK1 by decreasing its ubiquitination; core process.
    action: ACCEPT
    reason: Direct experimental demonstration of BAG2-mediated client stabilization.
    supported_by:
    - reference_id: PMID:24383081
      supporting_text: directly binds with and stabilises PINK1 by decreasing its
        ubiquitination
      reference_section_type: ABSTRACT
- term:
    id: GO:0050821
    label: protein stabilization
  evidence_type: IDA
  original_reference_id: PMID:25006867
  qualifier: involved_in
  review:
    summary: BAG2 stabilizes pathogenic ataxin-3 by inhibiting its ubiquitination; core
      process.
    action: ACCEPT
    reason: Direct experimental demonstration of BAG2-mediated client stabilization.
    supported_by:
    - reference_id: PMID:25006867
      supporting_text: stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
      reference_section_type: ABSTRACT
- term:
    id: GO:1901588
    label: dendritic microtubule
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: colocalizes_with
  review:
    summary: Neuronal dendritic-microtubule colocalization from the tau-triage study;
      context-specific.
    action: KEEP_AS_NON_CORE
    reason: Highly specific neuronal localization; retain as non-core.
- term:
    id: GO:1901800
    label: positive regulation of proteasomal protein catabolic process
  evidence_type: ISS
  original_reference_id: PMID:19228967
  qualifier: involved_in
  review:
    summary: BAG2/HSP70 promotes ubiquitin-independent proteasomal degradation of tau;
      supported but client/context-specific.
    action: KEEP_AS_NON_CORE
    reason: Supported by the tau-triage mechanism but context-specific to neuronal tau
      handling.
    supported_by:
    - reference_id: PMID:19228967
      supporting_text: deliver Tau to the
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16207813
  qualifier: enables
  review:
    summary: The underlying interaction is BAG2 with CHIP (and HSC70); bare protein binding
      is too generic and is better captured by the specific chaperone/E3-ligase binding terms.
    action: MARK_AS_OVER_ANNOTATED
    reason: protein binding is uninformative; the specific BAG2-CHIP and BAG2-HSC70
      interactions are represented by other terms in this review.
- term:
    id: GO:0010954
    label: positive regulation of protein processing
  evidence_type: IMP
  original_reference_id: PMID:16207813
  qualifier: involved_in
  review:
    summary: BAG2 stimulates chaperone-assisted maturation of CFTR; this is better captured
      as client stabilization/folding and negative regulation of ubiquitination. The
      generic "protein processing" term is a loose fit.
    action: KEEP_AS_NON_CORE
    reason: Supported for CFTR maturation but client/context-specific, and the term is a
      somewhat imprecise description of BAG2's CHIP-inhibition/stabilization mechanism.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: stimulates the chaperone-assisted maturation of CFTR
      reference_section_type: ABSTRACT
- term:
    id: GO:0044325
    label: transmembrane transporter binding
  evidence_type: IPI
  original_reference_id: PMID:16207813
  qualifier: enables
  review:
    summary: BAG2 recognizes CFTR (a transmembrane transporter) NBD1 peptides and stabilizes
      immature CFTR; transmembrane transporter binding is supported but client-specific.
    action: KEEP_AS_NON_CORE
    reason: CFTR is one client of BAG2; the binding is supported but not the universal
      core molecular function.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: also to stabilize immature CFTR conformations
      reference_section_type: DISCUSSION
- term:
    id: GO:0050821
    label: protein stabilization
  evidence_type: IDA
  original_reference_id: PMID:16207813
  qualifier: involved_in
  review:
    summary: BAG2 stabilizes immature CFTR conformations in addition to inhibiting CHIP;
      protein stabilization is a core BAG2 process.
    action: ACCEPT
    reason: Direct evidence that BAG2 stabilizes a chaperone client (CFTR).
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: also to stabilize immature CFTR conformations
      reference_section_type: DISCUSSION
- term:
    id: GO:0051087
    label: protein-folding chaperone binding
  evidence_type: IPI
  original_reference_id: PMID:16207813
  qualifier: enables
  review:
    summary: BAG2 binds HSC70 (a protein-folding chaperone) within CHIP complexes; chaperone
      binding is core.
    action: ACCEPT
    reason: Direct evidence of BAG2 association with HSC70 chaperone complexes underlies
      its co-chaperone function.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: the Hsc70 cochaperone
      reference_section_type: ABSTRACT
- term:
    id: GO:0101031
    label: protein folding chaperone complex
  evidence_type: IPI
  original_reference_id: PMID:16207813
  qualifier: part_of
  review:
    summary: BAG2 is a component of HSC70/CHIP chaperone complexes; membership in a
      protein-folding chaperone complex is core.
    action: ACCEPT
    reason: BAG2 is a main component of CHIP/HSC70 chaperone complexes, consistent with
      its co-chaperone role.
    supported_by:
    - reference_id: PMID:16207813
      supporting_text: We identified the Hsc70 cochaperone
      reference_section_type: ABSTRACT
- term:
    id: GO:0000774
    label: adenyl-nucleotide exchange factor activity
  evidence_type: IDA
  original_reference_id: PMID:24318877
  qualifier: enables
  review:
    summary: Direct biochemical demonstration of BAG2 NEF activity toward HSP70 (HSPA1A);
      this is the core molecular function.
    action: ACCEPT
    reason: BAG2 binds Hsp72 and functions in nucleotide/peptide release assays as a NEF,
      directly validating this molecular function.
    supported_by:
    - reference_id: PMID:24318877
      supporting_text: Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide
        exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).
      reference_section_type: ABSTRACT
    - reference_id: PMID:24318877
      supporting_text: their relative affinity values
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24318877
  qualifier: enables
  review:
    summary: The underlying interaction is BAG2 with HSP70 (HSPA1A); generic protein
      binding is uninformative and is captured by specific chaperone-binding/NEF terms.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding is too general; the BAG2-HSP70 interaction is represented
      by heat shock protein binding and NEF activity.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5252079
  qualifier: located_in
  review:
    summary: BAG2 is a cytosolic co-chaperone; cytosolic localization is the core
      compartment for its HSP70 NEF/CHIP-regulatory activity.
    action: ACCEPT
    reason: Consistent with BAG2 acting on cytosolic HSP70/HSC70 and CHIP complexes.
    supported_by:
    - reference_id: file:human/BAG2/BAG2-uniprot.txt
      supporting_text: Co-chaperone for HSP70 and HSC70 chaperone proteins
      reference_section_type: DATABASE_ENTRY
- term:
    id: GO:0019538
    label: protein metabolic process
  evidence_type: IDA
  original_reference_id: PMID:9873015
  qualifier: acts_upstream_of_or_within
  review:
    summary: The cited reference (PMID:9873015) is about glycogen synthesis in muscle cells
      and does not concern BAG2; this is a wrong-reference curation error rather than a
      genuine (if over-broad) annotation.
    action: REMOVE
    reason: The cited reference (PMID:9873015, "Control of glycogen synthesis in cultured
      human muscle cells") contains no evidence for any BAG2 role - it is a database
      mis-attribution. The annotation is unlikely to be correct based on the combined
      evidence and should be removed at source rather than merely downgraded.
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: TAS
  original_reference_id: PMID:9873016
  qualifier: involved_in
  review:
    summary: As an HSP70/HSC70 chaperone regulator, BAG2 participates in protein folding;
      supported by the foundational BAG-family chaperone-regulator study.
    action: ACCEPT
    reason: BAG2 modulates HSP70/HSC70 chaperone activity, consistent with a protein folding
      role.
    supported_by:
    - reference_id: PMID:9873016
      supporting_text: modulating their
      reference_section_type: ABSTRACT
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to
    orthologs using Ensembl Compara
  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:16207813
  title: BAG-2 acts as an inhibitor of the chaperone-associated ubiquitin ligase CHIP.
  findings: []
- id: PMID:18457437
  title: Identification of intracellular proteins associated with the EBV-encoded
    nuclear antigen 5 using an efficient TAP procedure and FT-ICR mass spectrometry.
  findings: []
- id: PMID:19228967
  title: The cochaperone BAG2 sweeps paired helical filament- insoluble tau from the
    microtubule.
  findings: []
- id: PMID:22365833
  title: Dynamic protein-protein interaction wiring of the human spliceosome.
  findings: []
- id: PMID:22810586
  title: Interpreting cancer genomes using systematic host network perturbations by
    tumour virus proteins.
  findings: []
- id: PMID:24318877
  title: Binding of human nucleotide exchange factors to heat shock protein 70 (Hsp70)
    generates functionally distinct complexes in vitro.
  findings: []
- id: PMID:24383081
  title: The BAG2 protein stabilises PINK1 by decreasing its ubiquitination.
  findings: []
- id: PMID:24510904
  title: Unbiased screen for interactors of leucine-rich repeat kinase 2 supports
    a common pathway for sporadic and familial Parkinson disease.
  findings: []
- id: PMID:24981860
  title: Human-chromatin-related protein interactions identify a demethylase complex
    required for chromosome segregation.
  findings: []
- id: PMID:25006867
  title: The BAG2 and BAG5 proteins inhibit the ubiquitination of pathogenic ataxin3-80Q.
  findings: []
- id: PMID:25036637
  title: A quantitative chaperone interaction network reveals the architecture of
    cellular protein homeostasis pathways.
  findings: []
- id: PMID:25416956
  title: A proteome-scale map of the human interactome network.
  findings: []
- id: PMID:25852190
  title: Integrative analysis of kinase networks in TRAIL-induced apoptosis provides
    a source of potential targets for combination therapy.
  findings: []
- id: PMID:25959826
  title: Quantitative interaction proteomics of neurodegenerative disease proteins.
  findings: []
- id: PMID:26496610
  title: A human interactome in three quantitative dimensions organized by stoichiometries
    and abundances.
  findings: []
- id: PMID:28386764
  title: Roles of tau protein in health and disease.
  findings: []
- id: PMID:29513927
  title: Comparative Protein Interaction Network Analysis Identifies Shared and Distinct
    Functions for the Human ROCO Proteins.
  findings: []
- id: PMID:29568061
  title: An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein
    interactions and subcellular localizations.
  findings: []
- id: PMID:30021884
  title: Histone Interaction Landscapes Visualized by Crosslinking Mass Spectrometry
    in Intact Cell Nuclei.
  findings: []
- id: PMID:31980649
  title: Extensive rewiring of the EGFR network in colorectal cancer cells expressing
    transforming levels of KRAS(G13D).
  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:34831344
  title: 'With or without You: Co-Chaperones Mediate Health and Disease by Modifying
    Chaperone Function and Protein Triage.'
  full_text_unavailable: true
  findings:
  - statement: Review framing BAG2 as an HSP70/HSC70 co-chaperone that modulates chaperone
      function and protein triage decisions (folding/stabilization vs degradation) in
      health and disease, consistent with its inhibition of CHIP/STUB1-mediated client
      ubiquitination.
- id: PMID:35167623
  title: DNAJB1-PRKACA in HEK293T cells induces LINC00473 overexpression that depends
    on PKA signaling.
  findings: []
- id: PMID:35266954
  title: The E3 ligase TRIM1 ubiquitinates LRRK2 and controls its localization, degradation,
    and toxicity.
  findings: []
- id: PMID:35271311
  title: 'OpenCell: Endogenous tagging for the cartography of human cellular organization.'
  findings: []
- id: PMID:37045861
  title: Interactome dynamics of RAF1-BRAF kinase monomers and dimers.
  findings: []
- id: PMID:39300217
  title: BAG2, MAD2L1, and MDK are cancer-driver genes and candidate targets for novel
    therapies in malignant pleural mesothelioma.
  full_text_unavailable: true
  findings:
  - statement: BAG2 is identified as a candidate cancer-driver gene and diagnostic-adjunct
      biomarker in malignant pleural mesothelioma, being significantly upregulated in
      tumor RNA-seq and showing moderate-to-strong immunohistochemical expression in
      mesothelioma but not in reactive mesothelium; this is a disease-association rather
      than a new molecular function for BAG2.
- id: PMID:40205054
  title: Multimodal cell maps as a foundation for structural and functional genomics.
  findings: []
- id: PMID:9873015
  title: Control of glycogen synthesis in cultured human muscle cells.
  findings: []
- id: PMID:9873016
  title: An evolutionarily conserved family of Hsp70/Hsc70 molecular chaperone regulators.
  findings: []
- id: Reactome:R-HSA-5252079
  title: HSP110s exchange ATP for ADP on HSP70s:ADP
  findings: []
- id: file:human/BAG2/BAG2-uniprot.txt
  title: BAG2 UniProtKB record (O95816)
  findings: []
- id: file:human/BAG2/BAG2-notes.md
  title: Manual BAG2 curation notes
  findings: []
core_functions:
- description: BAG2 acts as a nucleotide-exchange factor (NEF) for the HSP70/HSC70 molecular
    chaperones, binding the chaperone ATPase domain via its BAG domain and promoting ADP
    release to regulate the chaperone cycle and client release.
  molecular_function:
    id: GO:0000774
    label: adenyl-nucleotide exchange factor activity
  directly_involved_in:
  - id: GO:0006457
    label: protein folding
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: file:human/BAG2/BAG2-uniprot.txt
    supporting_text: a nucleotide-exchange factor (NEF) promoting the release of ADP from
    reference_section_type: DATABASE_ENTRY
  - reference_id: PMID:24318877
    supporting_text: Proteins with Bcl2-associated anthanogene (BAG) domains act as nucleotide
      exchange factors (NEFs) for the molecular chaperone heat shock protein 70 (Hsp70).
    reference_section_type: ABSTRACT
- description: BAG2 inhibits the chaperone-associated E3 ubiquitin ligase CHIP (STUB1) by
    abrogating CHIP/E2 cooperation, thereby negatively regulating ubiquitination of chaperone
    clients and shifting protein triage away from degradation.
  molecular_function:
    id: GO:0031625
    label: ubiquitin protein ligase binding
  directly_involved_in:
  - id: GO:0031397
    label: negative regulation of protein ubiquitination
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:16207813
    supporting_text: BAG-2 inhibits the ubiquitin ligase activity of CHIP by abrogating
      the CHIP/E2 cooperation
    reference_section_type: ABSTRACT
- description: BAG2 stabilizes specific chaperone clients (e.g., immature CFTR, PINK1,
    polyglutamine-expanded ataxin-3) by decreasing their ubiquitination, contributing to
    chaperone-assisted protein quality control.
  molecular_function:
    id: GO:0051087
    label: protein-folding chaperone binding
  directly_involved_in:
  - id: GO:0050821
    label: protein stabilization
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:24383081
    supporting_text: directly binds with and stabilises PINK1 by decreasing its ubiquitination
    reference_section_type: ABSTRACT
  - reference_id: PMID:25006867
    supporting_text: stabilise pathogenic ataxin3-80Q by inhibiting its ubiquitination
    reference_section_type: ABSTRACT
proposed_new_terms: []
suggested_questions:
- question: Given BAG2's notably lower affinity for HSP70 compared with BAG1 and BAG3, what
    determines its selective recruitment to specific clients and to CHIP complexes in vivo?
  experts:
  - Gestwicki JE
  - Höhfeld J
- question: Is the neuronal microtubule-tethered, ubiquitin-independent tau-degradation role
    of BAG2 a specialized function distinct from its general cytosolic co-chaperone activity?
  experts:
  - Kosik KS
- question: Does BAG2-mediated inhibition of CHIP/STUB1 stabilize HSP70-family chaperones
    (e.g., HSP72/HSPA1A) and pro-survival clients to confer apoptosis resistance, and is this
    a generalizable mechanism across the cancer contexts (mesothelioma, gastric, fibrolamellar)
    where BAG2 is reported to be upregulated?
  experts:
  - Behl C
  - Höhfeld J
suggested_experiments:
- hypothesis: BAG2 selectively inhibits CHIP-mediated ubiquitination of a defined subset of
    HSP70 clients rather than acting as a global CHIP inhibitor.
  description: Reconstitute HSC70/CHIP/E2 ubiquitination assays with purified BAG2 across a
    panel of clients (CFTR NBD1, PINK1, ataxin-3, tau) and quantify client-specific
    suppression of ubiquitination versus NEF activity.
  experiment_type: in vitro reconstituted ubiquitination assay
- hypothesis: BAG2 routes misfolded tau to ubiquitin-independent proteasomal degradation via
    microtubule tethering of the BAG2/HSP70 complex.
  description: Use neurons with BAG2 BAG-domain or microtubule-association mutants and measure
    Sarkosyl-insoluble/phospho-tau clearance, proteasome dependence, and ubiquitin
    requirement.
  experiment_type: cell-based tau clearance / proteasome dependence assay

BAG2

Gene Description

Existing Annotations Review

Core Functions

BAG2 acts as a nucleotide-exchange factor (NEF) for the HSP70/HSC70 molecular chaperones, binding the chaperone ATPase domain via its BAG domain and promoting ADP release to regulate the chaperone cycle and client release.

BAG2 inhibits the chaperone-associated E3 ubiquitin ligase CHIP (STUB1) by abrogating CHIP/E2 cooperation, thereby negatively regulating ubiquitination of chaperone clients and shifting protein triage away from degradation.

BAG2 stabilizes specific chaperone clients (e.g., immature CFTR, PINK1, polyglutamine-expanded ataxin-3) by decreasing their ubiquitination, contributing to chaperone-assisted protein quality control.

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Research report: Human BAG2 (BAG cochaperone 2; UniProt O95816)—functional annotation and recent research

1) Identity verification, key concepts, and definitions

2) Experimentally supported molecular functions and mechanisms

2.1 BAG2 as a NEF/co-chaperone for Hsp70/Hsc70

2.2 BAG2 as an inhibitor of CHIP/STUB1 ubiquitin ligase activity

2.3 BAG2 participates in large proteostasis complexes (complex recruitment hypothesis)

3) Subcellular localization and where BAG2 acts

4) Pathways and biological processes

4.1 Proteostasis and ubiquitin–proteasome system (UPS)

4.2 Aging-associated proteostasis changes

4.3 Apoptosis regulation (disease-context mechanistic pathway)

4.4 Autophagy/mitophagy and innate immunity—evidence status in this retrieval

5) Recent developments (prioritizing 2023–2024)

5.1 Neurodegeneration (computational network modeling; 2023)

5.2 Malignant pleural mesothelioma (MPM; 2024)

5.3 Liposarcoma prognostic associations (2024)

5.4 Fibrolamellar carcinoma (FLC) mechanistic expansion (2024)

5.5 Gastric cancer therapeutic axis proposal (2024)

6) Current applications and real-world implementations

7) Expert synthesis/interpretation (grounded in authoritative sources)

8) Key quantitative/statistical highlights (recent)

9) Evidence map (summary table)

10) Notes on scope limits of the retrieved evidence

11) Key references (URLs and publication dates)

Artifacts

Citations

📚 Additional Documentation

Notes

BAG2 (O95816) research notes

Identity / domain architecture

Core molecular function: HSP70/HSC70 nucleotide-exchange factor (co-chaperone)

CHIP (STUB1) E3 ligase inhibition / protein triage

Tau triage at the microtubule (neuronal context)

Substrate stabilization by reducing ubiquitination (disease-relevant clients)

Localization

Synthesis of core vs non-core

Falcon deep research findings (2026-06-07)

Pn Notes

BAG2 PN Consistency Notes

Source Files Checked

Deep Research Files

AIGR Review Snapshot

PN Consistency Summary

Full Consistency Review

PN Dossier Context

PN row 1: Cytonuclear proteostasis | Chaperone | HSP70 system | HSP70 nucleotide exchange factor | BAG domain subtype

PN row 2: Ubiquitin Proteasome System | Proteasome and associated proteins | adaptors | BAG

Projected GO annotations (2)

Note

📄 View Raw YAML