Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0043065 positive regulation of apoptotic process	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: NIX/BNIP3L was first characterized as a pro-apoptotic BCL-2/NIP3-family protein and can promote cell death in some contexts, but this is direction-dependent and atypical (necrosis/membrane permeability rather than classical caspase apoptosis). Reason: The pro-apoptotic role is genuine but secondary and context-dependent relative to the conserved mitophagy-receptor function; the same gene also has negative-regulation-of-apoptosis annotations, underscoring that cell-death regulation is contextual. Supporting Evidence: PMID:9973195 Overexpression of BNIP3alpha in transfected cells results in apoptosis and suppresses the antiapoptosis activity of E1B-19K and BCL-xL. PMID:21264228 in contrast to other mitochondrial Bcl-2 family proteins, NIX and BNIP3 are not involved in the release of cytochrome c and the resulting caspase-dependent apoptosis, but rather related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
GO:0043653 mitochondrial fragmentation involved in apoptotic process	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Mitochondrial fragmentation in an apoptotic context is a secondary, contextual aspect of NIX biology rather than its core mitophagy-receptor function. Reason: NIX can promote mitochondrial membrane permeabilization/necrosis-related death, but the conserved core function is selective autophagic clearance of mitochondria, not apoptotic fragmentation. Supporting Evidence: PMID:21264228 in contrast to other mitochondrial Bcl-2 family proteins, NIX and BNIP3 are not involved in the release of cytochrome c and the resulting caspase-dependent apoptosis, but rather related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
GO:0005783 endoplasmic reticulum	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: ER localization is reported for NIX (it was detected in nuclear envelope, ER and mitochondria, and linked to ER Ca2+ handling), but it is a secondary site relative to the mitochondrial outer membrane where the mitophagy-receptor function operates. Reason: ER localization is documented but is not the primary functional compartment; the is_active_in qualifier overstates ER as a site of NIX activity. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria PMID:21264228 NIX was also shown to localize to endoplasmic reticulum (ER) and increase the store of Ca++, leading to Ca++ influx into mitochondria and cell death
GO:0005741 mitochondrial outer membrane	IBA GO_REF:0000033	ACCEPT	Summary: The mitochondrial outer membrane is the core functional location of NIX, where its C-terminal transmembrane anchor inserts and its cytosolic LIR engages the autophagy machinery. Reason: This is the principal functional compartment for the mitophagy-receptor activity and is strongly supported by multiple independent studies. Supporting Evidence: PMID:20200478 Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation. PMID:21264228 A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap.
GO:0005634 nucleus	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: A nuclear/nuclear-envelope localization derives from the original B5 study; it is weakly supported and is not the functional compartment for the mitophagy-receptor role. Reason: is_active_in nucleus is not supported by a defined nuclear function; the only relevant primary data describe nuclear envelope localization, likely reflecting tail-anchored membrane behavior, not nucleoplasmic activity. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005635 nuclear envelope	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Nuclear envelope localization is reported in the original B5 study (with associated lamin binding), but it is a secondary, weakly characterized site rather than the functional mitophagy compartment. Reason: Nuclear envelope localization is documented experimentally but is not where the conserved mitophagy-receptor function acts; retained as non-core. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005635 nuclear envelope	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: Automated subcellular-location transfer of nuclear envelope localization, consistent with the experimental B5 data. Reason: Consistent with documented nuclear envelope localization but secondary to the mitochondrial outer membrane function. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005740 mitochondrial envelope	IEA GO_REF:0000002	MODIFY	Summary: Mitochondrial envelope is a less specific parent of the mitochondrial outer membrane, where NIX is actually anchored. Reason: The more precise and well-supported localization is the mitochondrial outer membrane; replace the broader envelope term. Proposed replacements: mitochondrial outer membrane Supporting Evidence: PMID:20200478 Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
GO:0005741 mitochondrial outer membrane	IEA GO_REF:0000044	ACCEPT	Summary: Automated location transfer of the well-supported mitochondrial outer membrane localization. Reason: Strongly supported as the core functional compartment. Supporting Evidence: PMID:20200478 Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
GO:0005783 endoplasmic reticulum	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: Automated transfer of ER localization, consistent with experimental detection of NIX in the ER. Reason: ER localization is documented but is a secondary site relative to the mitochondrial outer membrane. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0016020 membrane	IEA GO_REF:0000120	MARK AS OVER ANNOTATED	Summary: NIX is a single-pass tail-anchored membrane protein, so generic membrane localization is correct but uninformative. Reason: The generic membrane term is subsumed by the specific and well-supported mitochondrial outer membrane localization. Supporting Evidence: file:human/BNIP3L/BNIP3L-uniprot.txt Single-pass
GO:0043065 positive regulation of apoptotic process	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: Automated transfer of the pro-apoptotic process annotation; genuine but context-dependent and not the core function. Reason: Cell-death promotion by NIX is contextual and direction-dependent; secondary to mitophagy. Supporting Evidence: PMID:9973195 Overexpression of BNIP3alpha in transfected cells results in apoptosis and suppresses the antiapoptosis activity of E1B-19K and BCL-xL.
GO:0005515 protein binding	IPI PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation; the underlying B5 data describe specific self-association and BNIP3 heterodimerization, captured better by homodimerization activity. Reason: Bare protein binding is uninformative; the specific interactions are represented by the identical protein binding / homodimerization annotations from this same study. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0005515 protein binding	IPI PMID:16189514 Towards a proteome-scale map of the human protein-protein in...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a proteome-scale interaction map does not identify an interpretable NIX function.
GO:0005515 protein binding	IPI PMID:19060904 An empirical framework for binary interactome mapping.	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a binary interactome dataset does not specify a meaningful function.
GO:0005515 protein binding	IPI PMID:21516116 Next-generation sequencing to generate interactome datasets.	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from an interactome-mapping method is not functionally specific.
GO:0005515 protein binding	IPI PMID:22645275 Identification of novel ATP13A2 interactors and their role i...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from an ATP13A2/alpha-synuclein interactome study; uninformative for core NIX function. Reason: Bare protein binding does not specify a NIX function; the interaction is not tied to core mitophagy biology.
GO:0005515 protein binding	IPI PMID:24316735 Orphan nuclear receptor TR3 acts in autophagic cell death vi...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation from a TR3/NR4A1 autophagic-cell-death study; uninformative as bare protein binding. Reason: The term protein binding is too general; the NR4A1 interaction is not informative as core NIX function.
GO:0005515 protein binding	IPI PMID:24981860 Human-chromatin-related protein interactions identify a deme...	MARK AS OVER ANNOTATED	Summary: High-throughput chromatin-related interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a large-scale interaction study does not specify a NIX function.
GO:0005515 protein binding	IPI PMID:25416956 A proteome-scale map of the human interactome network.	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a proteome-scale interactome map is not functionally specific.
GO:0005515 protein binding	IPI PMID:25910212 Widespread macromolecular interaction perturbations in human...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a disease-interactome perturbation study is not functionally specific.
GO:0005515 protein binding	IPI PMID:27107012 Pooled-matrix protein interaction screens using Barcode Fusi...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a pooled interaction screen does not specify a NIX function.
GO:0005515 protein binding	IPI PMID:28514442 Architecture of the human interactome defines protein commun...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a large-scale interactome study is not functionally specific.
GO:0005515 protein binding	IPI PMID:31515488 Extensive disruption of protein interactions by genetic vari...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a variant-interaction study is not functionally specific.
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome.	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a reference binary interactome map is not functionally specific.
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a cell-specific interactome remodeling study is not functionally specific.
GO:0005515 protein binding	IPI PMID:34845370 SARS-CoV-2 ORF10 suppresses the antiviral innate immune resp...	MARK AS OVER ANNOTATED	Summary: This protein-binding annotation reflects the specific, functionally important interaction of NIX with SARS-CoV-2 ORF10 and LC3B during virus-hijacked mitophagy; as bare protein binding it is uninformative. Reason: The underlying interaction is meaningful (ORF10/LC3B binding driving NIX-mediated mitophagy), but the generic protein binding term does not capture it; the antiviral mitophagy biology is curated under defense response to virus. Supporting Evidence: PMID:34845370 ORF10 was translocated to mitochondria by interacting with the mitophagy receptor Nip3-like protein X (NIX) and induced mitophagy through its interaction with both NIX and LC3B
GO:0005515 protein binding	IPI PMID:39526800 A comprehensive two-hybrid analysis to explore the Legionell...	MARK AS OVER ANNOTATED	Summary: High-throughput Legionella effector two-hybrid interactome protein-binding annotation; uninformative for NIX function. Reason: Generic protein binding from a pathogen-effector interactome screen is not functionally specific for NIX.
GO:0005515 protein binding	IPI PMID:9973195 BNIP3alpha: a human homolog of mitochondrial proapoptotic pr...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation; the underlying data describe specific interactions with E1B-19K, BCL-2 and BCL-xL, not informative as bare binding. Reason: Bare protein binding is uninformative; the specific anti-apoptotic-protein interactions are better represented elsewhere. Supporting Evidence: PMID:9973195 BNIP3alpha interacts with viral antiapoptosis protein E1B-19K and cellular antiapoptosis proteins BCL-2 and BCL-xL.
GO:0042802 identical protein binding	IPI PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	ACCEPT	Summary: NIX/B5 self-associates, and the original study directly shows it binds itself; identical protein binding (self-association) is supported. Reason: Self-association is directly demonstrated and is a genuine, informative molecular property of NIX. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0042802 identical protein binding	IPI PMID:16189514 Towards a proteome-scale map of the human protein-protein in...	ACCEPT	Summary: NIX self-association is recorded as identical protein binding in a high-throughput interactome (IntAct O60238-O60238); consistent with directly demonstrated self-association. Reason: NIX self-association is independently supported by direct biochemistry; the high-throughput identical-protein-binding hit is consistent and informative. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0042802 identical protein binding	IPI PMID:21516116 Next-generation sequencing to generate interactome datasets.	ACCEPT	Summary: NIX self-association recorded as identical protein binding from interactome mapping; consistent with demonstrated self-association. Reason: Consistent with directly demonstrated NIX self-association and informative as a homodimerization property. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0042802 identical protein binding	IPI PMID:25416956 A proteome-scale map of the human interactome network.	ACCEPT	Summary: NIX self-association recorded as identical protein binding from a proteome-scale interactome; consistent with demonstrated self-association. Reason: Consistent with directly demonstrated NIX self-association. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0042802 identical protein binding	IPI PMID:27107012 Pooled-matrix protein interaction screens using Barcode Fusi...	ACCEPT	Summary: NIX self-association recorded as identical protein binding from a pooled interaction screen; consistent with demonstrated self-association. Reason: Consistent with directly demonstrated NIX self-association. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0005739 mitochondrion	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: General mitochondrial localization; correct but less specific than the mitochondrial outer membrane localization. Reason: Accurate but subsumed by the more precise mitochondrial outer membrane annotation. Supporting Evidence: PMID:9973195 Like BNIP3, BNIP3alpha seems to be predominantly localized in mitochondria.
GO:0010917 negative regulation of mitochondrial membrane potential	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: NIX/BNIP3 can affect mitochondrial membrane potential/permeability (linked to necrosis and to depolarization-triggered mitophagy), a contextual mitochondrial effect. Reason: Effects on membrane potential are documented but are a downstream/contextual aspect rather than the core mitophagy-receptor activity. Supporting Evidence: PMID:21264228 related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
GO:0035794 positive regulation of mitochondrial membrane permeability	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: NIX/BNIP3 are linked to opening of the mitochondrial permeability transition pore and necrosis-related membrane permeabilization, a contextual function. Reason: Supported as a contextual mitochondrial membrane effect; secondary to mitophagy-receptor activity. Supporting Evidence: PMID:21264228 related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
GO:0042802 identical protein binding	IEA GO_REF:0000120	ACCEPT	Summary: Automated identical-protein-binding annotation, consistent with directly demonstrated NIX self-association. Reason: Consistent with documented NIX self-association. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:1901524 regulation of mitophagy	IEA GO_REF:0000107	ACCEPT	Summary: Regulation of mitophagy is a core process for NIX, which acts as a mitochondrial receptor connecting mitochondria to the autophagy machinery via LC3/GABARAP. Reason: Mitophagy is the defining conserved function of NIX and is strongly supported. Supporting Evidence: PMID:20200478 Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
GO:1903747 regulation of protein localization to mitochondrion	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: NIX recruits autophagy machinery (LC3/GABARAP) to mitochondria; this can be viewed as regulating protein localization to the mitochondrion, but it is better represented by mitophagy receptor activity. Reason: The annotation captures a mechanistic aspect (recruitment of Atg8-family proteins to mitochondria) of the core mitophagy function but as a broad regulatory term is less precise; retained as non-core. Supporting Evidence: PMID:20200478 Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
GO:0005739 mitochondrion	IDA GO_REF:0000052	KEEP AS NON CORE	Summary: Immunofluorescence-based mitochondrial localization, consistent with the predominant mitochondrial localization of NIX. Reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization. Supporting Evidence: PMID:9973195 Like BNIP3, BNIP3alpha seems to be predominantly localized in mitochondria.
GO:0016607 nuclear speck	IDA GO_REF:0000052	MARK AS OVER ANNOTATED	Summary: A nuclear speck localization (HPA immunofluorescence) is weakly supported and inconsistent with the established tail-anchored mitochondrial outer membrane biology of NIX. Reason: No defined nuclear-speck function exists for NIX; this single-source localization likely reflects antibody/overexpression artifact and is not the functional compartment.
GO:0005739 mitochondrion	HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an...	KEEP AS NON CORE	Summary: High-throughput mitochondrial proteome localization, consistent with NIX being a mitochondrial protein. Reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization. Supporting Evidence: PMID:34800366 mitochondrial proteome
GO:0043069 negative regulation of programmed cell death	IGI PMID:19273585 Hypoxia-induced autophagy is mediated through hypoxia-induci...	KEEP AS NON CORE	Summary: Under hypoxia, HIF-induced BNIP3/BNIP3L promote pro-survival autophagy and their ablation triggers cell death, supporting a negative regulation of programmed cell death role in this context. Reason: Supported by genetic evidence but contextual (hypoxia/survival); secondary to the core mitophagy-receptor function. Supporting Evidence: PMID:19273585 the ablation of BNIP3 and/or BNIP3L triggers cell death PMID:19273585 Hypoxia-induced autophagy via BNIP3 and BNIP3L is clearly a survival mechanism that promotes tumor progression.
GO:0016239 positive regulation of macroautophagy	IGI PMID:19273585 Hypoxia-induced autophagy is mediated through hypoxia-induci...	ACCEPT	Summary: BNIP3/BNIP3L are required for hypoxia-induced macroautophagy and their atypical BH3 domains can initiate autophagy by disrupting the Bcl-2-Beclin1 complex. Reason: Positive regulation of macroautophagy is well supported by combined silencing/ectopic expression and BH3-peptide experiments, and is closely tied to the autophagy-receptor biology of NIX. Supporting Evidence: PMID:19273585 the combined silencing of these two HIF targets suppresses hypoxia-mediated autophagy PMID:19273585 the ectopic expression of both BNIP3 and BNIP3L in normoxia activates autophagy
GO:0071456 cellular response to hypoxia	IGI PMID:19273585 Hypoxia-induced autophagy is mediated through hypoxia-induci...	KEEP AS NON CORE	Summary: BNIP3L is a HIF target that mediates hypoxia-induced autophagy, supporting a role in the cellular response to hypoxia. Reason: Supported as part of the hypoxia/HIF-autophagy axis but is a contextual upstream process rather than the core molecular function. Supporting Evidence: PMID:19273585 the combined silencing of these two HIF targets suppresses hypoxia-mediated autophagy
GO:0005741 mitochondrial outer membrane	TAS Reactome:R-HSA-6798004	ACCEPT	Summary: Reactome-curated mitochondrial outer membrane localization (TP53 stimulates BNIP3L expression pathway). Reason: Consistent with the well-supported core localization. Supporting Evidence: PMID:20200478 Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
GO:0005741 mitochondrial outer membrane	TAS Reactome:R-HSA-6801195	ACCEPT	Summary: Reactome-curated mitochondrial outer membrane localization (STEAP3 binds BNIP3L pathway). Reason: Consistent with the well-supported core localization. Supporting Evidence: PMID:20200478 Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
GO:0005515 protein binding	IPI PMID:20200478 Nix, a receptor protein for mitophagy in mammals.	MARK AS OVER ANNOTATED	Summary: This protein-binding annotation reflects the functionally central interaction of NIX with the Atg8 homologs LC3/GABARAP, but as bare protein binding it is uninformative. Reason: The underlying LC3/GABARAP interaction is the molecular basis of NIX mitophagy-receptor activity; bare protein binding does not capture this and the function is curated under regulation of mitophagy. Supporting Evidence: PMID:20200478 Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
GO:0043065 positive regulation of apoptotic process	IDA PMID:9973195 BNIP3alpha: a human homolog of mitochondrial proapoptotic pr...	KEEP AS NON CORE	Summary: Overexpression of BNIP3alpha induced apoptosis in transfected cells, providing direct (if overexpression-based) evidence for a pro-apoptotic role. Reason: Direct evidence supports a pro-apoptotic capacity, but it is context-dependent/overexpression-driven and secondary to the conserved mitophagy function. Supporting Evidence: PMID:9973195 Overexpression of BNIP3alpha in transfected cells results in apoptosis and suppresses the antiapoptosis activity of E1B-19K and BCL-xL.
GO:0005515 protein binding	IPI PMID:21264221 Possible existence of lysosome-like organella within mitocho...	MARK AS OVER ANNOTATED	Summary: Generic protein-binding annotation associated with the Mieap/MALM mitochondrial quality-control studies; uninformative as bare binding. Reason: Bare protein binding is uninformative; the relevant NIX-SPATA18/Mieap interaction is curated via the mitochondrial protein catabolic process annotation.
GO:0005741 mitochondrial outer membrane	IMP PMID:21264228 Mieap, a p53-inducible protein, controls mitochondrial quali...	ACCEPT	Summary: NIX localizes to and acts at the mitochondrial outer membrane, where it interacts with Mieap via its BH3 domain; mutational/localization analysis supports this compartment. Reason: Directly supported core localization. Supporting Evidence: PMID:21264228 A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap.
GO:0035694 mitochondrial protein catabolic process	IMP PMID:21264228 Mieap, a p53-inducible protein, controls mitochondrial quali...	ACCEPT	Summary: NIX is an essential mediator of MALM (Mieap-induced accumulation of lysosome-like organelles within mitochondria), a non-canonical process that degrades oxidized mitochondrial proteins; NIX deficiency impairs MALM. Reason: Loss-of-function (NIX knockdown) directly impairs MALM, supporting NIX involvement in mitochondrial protein catabolism within the mitochondrial quality-control context. Supporting Evidence: PMID:21264228 Deficiency of NIX also completely impaired MALM.
GO:0005521 lamin binding	IPI PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	KEEP AS NON CORE	Summary: Lamin binding derives from the original B5/nuclear-envelope study; it is a specific but secondary interaction not central to the mitophagy-receptor function. Reason: Retained as a specific (non-generic) binding annotation, but it is contextual to the nuclear-envelope localization and not the core function. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005521 lamin binding	IDA PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	KEEP AS NON CORE	Summary: Direct-assay lamin binding from the original B5 study; specific but secondary. Reason: Specific binding annotation tied to nuclear-envelope localization; not the core function. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005635 nuclear envelope	IDA PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	KEEP AS NON CORE	Summary: Direct localization of B5/NIX to the nuclear envelope in the original study; secondary site. Reason: Documented but secondary localization relative to the mitochondrial outer membrane. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005739 mitochondrion	IDA PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	KEEP AS NON CORE	Summary: Direct mitochondrial localization in the original B5 study. Reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0005783 endoplasmic reticulum	IDA PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	KEEP AS NON CORE	Summary: Direct ER localization in the original B5 study; secondary site. Reason: Documented but secondary localization relative to the mitochondrial outer membrane. Supporting Evidence: PMID:10381623 localizes in nuclear envelope, endoplasmic reticulum and mitochondria
GO:0016020 membrane	TAS PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	MARK AS OVER ANNOTATED	Summary: NIX/B5 contains a C-terminal transmembrane region; generic membrane localization is correct but uninformative. Reason: Subsumed by the specific mitochondrial outer membrane localization. Supporting Evidence: PMID:10381623 contains the putative BH3 and transmembrane regions
GO:0042803 protein homodimerization activity	IDA PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	ACCEPT	Summary: NIX/B5 self-associates (binds itself), supporting protein homodimerization activity as a genuine molecular property. Reason: Directly demonstrated self-association; informative homodimerization activity. Supporting Evidence: PMID:10381623 B5 binds strongly to Nip3 and itself
GO:0043066 negative regulation of apoptotic process	IDA PMID:10381623 A novel adenovirus E1B19K-binding protein B5 inhibits apopto...	KEEP AS NON CORE	Summary: In the original B5 study, NIX did not itself induce apoptosis but inhibited Nip3(BNIP3)-induced apoptosis, supporting an anti-apoptotic capacity in this context. Reason: This anti-apoptotic effect is genuine but direction- and context-dependent (the same protein can also promote death); secondary to mitophagy. Supporting Evidence: PMID:10381623 B5 does not induce apoptosis, but inhibits apoptosis induced by Nip3
GO:0005739 mitochondrion	IDA PMID:9973195 BNIP3alpha: a human homolog of mitochondrial proapoptotic pr...	KEEP AS NON CORE	Summary: Direct mitochondrial localization of BNIP3alpha/NIX. Reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization. Supporting Evidence: PMID:9973195 Like BNIP3, BNIP3alpha seems to be predominantly localized in mitochondria.
GO:0051607 defense response to virus	IDA PMID:9973195 BNIP3alpha: a human homolog of mitochondrial proapoptotic pr...	REMOVE	Summary: The cited 1999 BNIP3alpha paper is about apoptosis/anti-apoptotic-protein interactions and does not provide direct evidence for defense response to virus; the genuine antiviral connection (NIX-mediated mitophagy degrading MAVS) is established by later work, but viruses hijack this for immune evasion rather than NIX acting in host antiviral defense. Reason: The original reference (PMID:9973195) was reviewed and is about apoptosis/anti-apoptotic-protein interactions; it provides no evidence for a defense-response-to-virus role (this is therefore a removal on reviewed evidence, not an UNDECIDED due to inaccessible literature). Later literature (PMID:34845370) shows NIX-mediated mitophagy is hijacked by SARS-CoV-2 ORF10 to degrade MAVS and suppress innate immunity, the opposite of host antiviral defense; KSHV vIRF-1 similarly co-opts NIX. The annotation is unlikely to be correct based on the combined evidence. Supporting Evidence: PMID:34845370 ORF10 was translocated to mitochondria by interacting with the mitophagy receptor Nip3-like protein X (NIX) and induced mitophagy through its interaction with both NIX and LC3B PMID:34845370 NIX-mediated mitophagy is responsible for the elimination of spontaneously aggregated MAVS

Core Functions

BNIP3L/NIX functions as a mitophagy receptor at the mitochondrial outer membrane. Anchored by its C-terminal transmembrane helix with an N-terminal cytosolic region containing an LC3-interacting region, it directly binds Atg8-family proteins (LC3 and GABARAP) to tether mitochondria to the forming autophagosome, driving selective autophagic clearance of mitochondria. This is essential for mitochondrial elimination during terminal erythroid/reticulocyte maturation and contributes to developmentally programmed and stress-induced mitochondrial turnover.

Directly Involved In:

regulation of mitophagy positive regulation of macroautophagy

Cellular Locations:

mitochondrial outer membrane

Supporting Evidence:

PMID:20200478
Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
PMID:20200478
Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.

Under hypoxia, NIX (a HIF target) promotes pro-survival macroautophagy. Its atypical BH3 domain can disrupt the Bcl-2-Beclin1 complex to initiate autophagy without inducing cell death, and combined loss of BNIP3 and BNIP3L suppresses hypoxia-induced autophagy.

Directly Involved In:

positive regulation of macroautophagy cellular response to hypoxia

Cellular Locations:

mitochondrial outer membrane

Supporting Evidence:

PMID:19273585
the atypical BH3 domains of hypoxia-induced BNIP3/BNIP3L have
PMID:19273585
the ectopic expression of both BNIP3 and BNIP3L in normoxia activates autophagy

NIX participates in non-canonical mitochondrial quality control via ROS-dependent interaction with SPATA18/MIEAP, acting as an essential mediator of MALM that degrades oxidized mitochondrial proteins; NIX deficiency abolishes MALM.

Directly Involved In:

mitochondrial protein catabolic process

Cellular Locations:

mitochondrial outer membrane

Supporting Evidence:

PMID:21264228
A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap.
PMID:21264228
Deficiency of NIX also completely impaired MALM.

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:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000052

Gene Ontology annotation based on curation of immunofluorescence data

GO_REF:0000107

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

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10381623

A novel adenovirus E1B19K-binding protein B5 inhibits apoptosis induced by Nip3 by forming a heterodimer through the C-terminal hydrophobic region.

PMID:16189514

Towards a proteome-scale map of the human protein-protein interaction network.

PMID:19060904

An empirical framework for binary interactome mapping.

PMID:19273585

Hypoxia-induced autophagy is mediated through hypoxia-inducible factor induction of BNIP3 and BNIP3L via their BH3 domains.

PMID:20200478

Nix, a receptor protein for mitophagy in mammals.

PMID:21264221

Possible existence of lysosome-like organella within mitochondria and its role in mitochondrial quality control.

PMID:21264228

Mieap, a p53-inducible protein, controls mitochondrial quality by repairing or eliminating unhealthy mitochondria.

PMID:21516116

Next-generation sequencing to generate interactome datasets.

PMID:22645275

Identification of novel ATP13A2 interactors and their role in α-synuclein misfolding and toxicity.

PMID:24316735

Orphan nuclear receptor TR3 acts in autophagic cell death via mitochondrial signaling pathway.

PMID:24981860

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

PMID:25416956

A proteome-scale map of the human interactome network.

PMID:25910212

Widespread macromolecular interaction perturbations in human genetic disorders.

PMID:27107012

Pooled-matrix protein interaction screens using Barcode Fusion Genetics.

PMID:28514442

Architecture of the human interactome defines protein communities and disease networks.

PMID:31515488

Extensive disruption of protein interactions by genetic variants across the allele frequency spectrum in human populations.

PMID:32296183

A reference map of the human binary protein interactome.

PMID:33961781

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

PMID:34800366

Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context.

PMID:36215693

BNIP3L/NIX regulates both mitophagy and pexophagy.

NIX, anchored in the mitochondrial outer membrane, also independently localizes to peroxisomes and drives their selective autophagic clearance (pexophagy), and Nix-null mouse tissue has increased peroxisomal content, showing that NIX acts as a selective autophagy receptor for more than one organelle.

PMID:37102372

FBXL4 ubiquitin ligase deficiency promotes mitophagy by elevating NIX levels.

A CRISPR screen of human E3 ubiquitin ligases identified VHL and FBXL4 as the strongest negative regulators of basal mitophagy, both converging on the mitophagy receptors BNIP3 and BNIP3L/NIX; FBXL4 destabilizes NIX/BNIP3 directly while VHL acts by suppressing HIF-1alpha-mediated transcription, and depletion of NIX is sufficient to restore mitophagy levels.

PMID:37161784

FBXL4 suppresses mitophagy by restricting the accumulation of NIX and BNIP3 mitophagy receptors.

The SCF(FBXL4) ubiquitin ligase complex localizes to the mitochondrial outer membrane in unstressed cells and constitutively ubiquitylates and degrades the mitophagy receptors NIX and BNIP3 to suppress basal mitophagy; pathogenic FBXL4 variants causing mtDNA depletion syndrome (MTDPS13) fail to mediate this turnover, linking dysregulated NIX accumulation to excessive basal mitophagy.

PMID:37621214

Nix interacts with WIPI2 to induce mitophagy.

In addition to its LIR motif that binds ATG8 proteins, NIX contains a minimal essential region (MER) that binds and recruits the autophagy effector WIPI2 to mitochondria; both the MER and the LIR are required for robust mitophagy, with the LIR reorganizing WIPI2 into puncta even in the absence of ATG8 proteins.

PMID:38991726

Dual-localized PPTC7 limits mitophagy through proximal and dynamic interactions with BNIP3 and NIX.

A pool of the mitochondrial phosphatase PPTC7 localizes to the outer mitochondrial membrane, dynamically associates with BNIP3 and NIX, and promotes their proteasomal turnover to limit basal mitophagy, acting post-transcriptionally and independently of HIF-1alpha stabilization.

PMID:38992176

PPTC7 antagonizes mitophagy by promoting BNIP3 and NIX degradation via SCF(FBXL4).

PPTC7 is an essential cofactor for SCF(FBXL4)-mediated degradation of the BNIP3 and NIX mitophagy receptors, acting as an outer-mitochondrial-membrane adaptor that links BNIP3/NIX to FBXL4 to suppress both steady-state and induced mitophagy, with the turnover function independent of PPTC7 phosphatase activity.

PMID:34845370

SARS-CoV-2 ORF10 suppresses the antiviral innate immune response by degrading MAVS through mitophagy.

PMID:39526800

A comprehensive two-hybrid analysis to explore the Legionella pneumophila effector-effector interactome.

PMID:9973195

BNIP3alpha: a human homolog of mitochondrial proapoptotic protein BNIP3.

Reactome:R-HSA-6798004

TP53 stimulates BNIP3L expression

Reactome:R-HSA-6801195

STEAP3 binds BNIP3L

file:human/BNIP3L/BNIP3L-uniprot.txt

BNIP3L (NIX) UniProtKB record O60238

file:human/BNIP3L/BNIP3L-notes.md

Manual BNIP3L curation notes

Suggested Experiments

Experiment: Compare wild-type NIX with LIR-motif point mutants (abolishing LC3/GABARAP binding) for their ability to rescue mitochondrial clearance during reticulocyte maturation and stress-induced mitophagy in NIX-null cells, using flow cytometry of mitochondrial mass and mito-Keima/mito-QC reporters.

Hypothesis: NIX functions as an LIR-dependent mitophagy receptor whose Atg8-family binding is required for programmed mitochondrial clearance.

Type: structure-function rescue and mitophagy flux assay

Experiment: Knock out NIX in cells and measure MAVS levels, type I interferon induction, and viral replication with and without virus-encoded mitophagy inducers (e.g., ORF10), distinguishing host-protective versus virus-exploited roles.

Hypothesis: NIX-mediated mitophagy is required for MAVS turnover and shapes innate antiviral signaling.

Type: loss-of-function antiviral signaling assay

Experiment: In NIX-null cells reconstituted with wild-type versus LIR-mutant NIX, quantify pexophagy flux (pexo-QC/pexophagy reporters and peroxisomal marker PMP70 loss) under iron chelation and during cardiomyocyte/erythroid differentiation, and use organelle fractionation plus targeted (peroxisome- vs mitochondria-restricted) NIX constructs to test whether peroxisomal cargo selection is separable from mitochondrial mitophagy.

Hypothesis: NIX acts as a selective autophagy receptor for peroxisomes (pexophagy) in addition to mitochondria, using a peroxisome-localized pool distinct from its mitochondrial pool.

Type: structure-function rescue and selective-autophagy flux assay

Deep Research

Falcon

(BNIP3L-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 21 citations 2 artifacts 2026-06-07T05:25:16.432438

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000032 The document provides two schematic figures that directly address your request. Figure 1 (page 2) details the domain architecture o (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.

Comprehensive research report: Human BNIP3L (NIX) — functional annotation (UniProt O60238)

1) Gene/protein identity verification (mandatory)

The literature consistently identifies NIX as the protein product of the human gene BNIP3L (a paralog of BNIP3), functioning as a selective autophagy/mitophagy receptor. A 2024 mini-review explicitly states that the BNIP3 pathway is mediated by BNIP3 and its paralog NIX (gene name BNIP3L), and describes both as mitophagy receptors (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). Multiple 2023 sources similarly treat NIX = BNIP3L and distinguish it from BNIP3 while emphasizing related domain organization and partial sequence homology (~50%) (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2). Therefore, the target entity is human BNIP3L/NIX, consistent with UniProt O60238, and not BNIP3 (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2).

2) Key concepts and definitions (current understanding)

2.1 Receptor-mediated mitophagy

Mitophagy is selective autophagy targeting mitochondria for lysosomal degradation. Unlike ubiquitin-driven PINK1/Parkin mitophagy, receptor-mediated mitophagy uses outer mitochondrial membrane (OMM) receptors that directly recruit autophagy machinery (marinkovic2021abriefoverview pages 1-1, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). BNIP3L/NIX is among the most-studied mammalian receptors in this class and is central to developmental/programmed removal of mitochondria, particularly in erythroid maturation (marinkovic2021abriefoverview pages 1-1, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3).

2.2 BNIP3L/NIX protein class and topology

BNIP3 and NIX are described as single-pass, C-terminal transmembrane proteins localized to the outer mitochondrial membrane (tail-anchored topology), positioning most of the protein in the cytosol for interaction with autophagy proteins (delgado2023theermembrane pages 1-2, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). This topology is a defining structural feature underlying their receptor activity (delgado2023theermembrane pages 1-2, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3).

2.3 LIR (LC3-interacting region) and ATG8 proteins

A core concept in receptor-mediated autophagy is the LC3-interacting region (LIR), a short motif in receptors that binds ATG8-family proteins on the growing autophagosomal membrane (LC3 and GABARAP families in humans) (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). NIX contains a functional LIR enabling recruitment of LC3/GABARAP to mitochondria (bunker2023nixinteractswith pages 1-2, marinkovic2021abriefoverview pages 2-3).

2.4 MER (minimal essential region)

Beyond the LIR, NIX contains an experimentally defined minimal essential region (MER). A 2023 EMBO Journal study showed that the MER is mechanistically important and interacts with the autophagy effector WIPI2, recruiting WIPI2 to mitochondria (bunker2023nixinteractswith pages 1-2). This extended mechanism is now part of current understanding of how transmembrane mitophagy receptors can initiate autophagosome biogenesis downstream of canonical initiation complexes (bunker2023nixinteractswith pages 1-2).

2.5 BH3-only domain (atypical)

BNIP3 and NIX contain an atypical BH3-only domain (BCL2 family–linked), historically connecting these proteins to apoptosis/cell-death biology, though its precise role in mitophagy regulation remains incompletely defined (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). Some sources connect BH3-family features to interactions with BCL2/Beclin-1 axis relevant to macroautophagy control (field2024theroleof pages 20-25).

3) Molecular function: what BNIP3L/NIX “does”

3.1 Primary function: selective autophagy receptor for mitochondria

The primary molecular function of BNIP3L/NIX is to act as an OMM-embedded selective autophagy receptor that links mitochondria to the autophagy machinery to drive mitophagy (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, marinkovic2021abriefoverview pages 2-3). It recruits ATG8 proteins (LC3/GABARAP) via its LIR, enabling formation/expansion of autophagosomal membranes around mitochondria (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, marinkovic2021abriefoverview pages 2-3).

3.2 Dual mechanism: LIR + MER/WIPI2 for robust mitophagy (major 2023 advance)

A key mechanistic advance is the demonstration that both NIX’s LIR and MER contribute to robust mitophagy. Using chemically induced dimerization approaches, Bunker et al. (EMBO J, Aug 2023) showed that the MER recruits WIPI2 to mitochondria and that the LIR helps reorganize WIPI2 into puncta even in the absence of ATG8 proteins, together enabling strong mitophagy (bunker2023nixinteractswith pages 1-2).

3.3 Additional selective autophagy role: pexophagy (peroxisome autophagy)

BNIP3L/NIX is not restricted to mitochondria. A 2022 EMBO Journal paper provided direct evidence that NIX can independently localize to peroxisomes and drive pexophagy (selective degradation of peroxisomes), including under iron chelation and differentiation contexts (wilhelm2022bnip3lnixregulatesboth pages 1-2, wilhelm2022bnip3lnixregulatesboth pages 10-11). This is relevant to human physiology because CD34+ primary human erythroid cultures showed progressive loss of the peroxisomal marker PMP70 during differentiation, consistent with programmed peroxisome turnover in these contexts (wilhelm2022bnip3lnixregulatesboth pages 10-11).

4) Subcellular localization: where BNIP3L/NIX acts

Outer mitochondrial membrane (OMM): Core receptor function for mitophagy occurs from the OMM; BNIP3 and NIX are described as OMM proteins targeted by a single C-terminal transmembrane domain (delgado2023theermembrane pages 1-2, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3).
Peroxisomes (subset/pool): NIX can localize to peroxisomes independently and promote pexophagy, particularly under iron chelation/hypoxia-linked transcriptional programs (wilhelm2022bnip3lnixregulatesboth pages 1-2, wilhelm2022bnip3lnixregulatesboth pages 7-9).

5) Pathways and regulation (focus on 2023–2024)

5.1 Transcriptional control by hypoxia signaling (HIF-1α) and VHL

BNIP3/NIX are described as transcriptional targets of HIF-1α and are induced under hypoxia or iron chelation (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2). FBXL4 and VHL-centered cullin-RING ligase pathways converge on restraining BNIP3/NIX: VHL limits HIF-1α activity (thereby limiting BNIP3/NIX transcription), while FBXL4 restricts receptor abundance post-translationally (elcocks2023fbxl4ubiquitinligase pages 1-2, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2).

5.2 Post-translational “brakes” restricting basal mitophagy: FBXL4 and PPTC7

A major 2023–2024 theme is that cells actively prevent excessive receptor-mediated mitophagy by controlling NIX protein abundance.

FBXL4/SCF E3 ligase pathway (2023): SCF(FBXL4) localizes to mitochondria in unstressed cells and constitutively ubiquitylates and degrades NIX and BNIP3, suppressing basal mitophagy (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2). Independent CRISPR screening of E3 ligases identified VHL and FBXL4 as the strongest negative regulators of basal mitophagy, converging on BNIP3 and BNIP3L/NIX (elcocks2023fbxl4ubiquitinligase pages 1-2). FBXL4 pathogenic variants associated with mitochondrial disease fail to mediate BNIP3/NIX turnover (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, nguyen‐dien2023fbxl4suppressesmitophagy pages 9-10).
PPTC7 as a cofactor/adapter limiting BNIP3/NIX (2024): Two complementary 2024 studies place PPTC7 as a negative regulator of BNIP3/NIX-mediated mitophagy. In Life Science Alliance (Jul 2024), PPTC7 is described as dual-localized (matrix and outer membrane fractions) and promotes ubiquitin-mediated turnover of BNIP3/NIX; Pptc7 KO mice show fully penetrant perinatal lethality with metabolic defects (wei2024duallocalizedpptc7limits pages 1-2). In EMBO Reports (Jul 2024), PPTC7’s catalytic integrity and binding interface are linked to BNIP3/NIX turnover, and an NIX Arg147-centered motif is required for PPTC7 binding and turnover (nguyendien2024pptc7antagonizesmitophagy pages 22-24).

5.3 Phosphoregulation and dimerization

BNIP3L/NIX activity is regulated by phosphorylation and oligomerization. A review notes that phosphorylation of Ser34/Ser35 in/near the LIR enhances recruitment of autophagosomes to mitochondria, while C-terminal phosphorylation state (e.g., Ser212) is linked to monomer–dimer equilibrium and stabilization of dimers (marinkovic2021abriefoverview pages 2-3). Dimerization through the transmembrane domain is repeatedly implicated as functionally important (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, marinkovic2021abriefoverview pages 2-3).

6) Physiological roles (precision over pleiotropy)

6.1 Erythroid maturation and programmed mitochondrial clearance

A central, well-supported physiological role is programmed removal of mitochondria during terminal erythroid differentiation. Reviews emphasize BNIP3L/NIX as critical in reticulocyte/erythrocyte maturation and programmed mitochondrial elimination (marinkovic2021abriefoverview pages 1-1, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). This is often used as the canonical example of receptor-mediated mitophagy in mammals.

6.2 Basal mitophagy and organelle homeostasis

BNIP3/NIX contribute not only to stress-induced mitophagy but also to basal mitophagic flux. Combined ablation of both receptors in HeLa cells is reported to nearly abolish steady-state mitophagy as measured by mito-mKeima (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3). This supports a broader homeostatic role for BNIP3L/NIX in maintaining mitochondrial quality/quantity.

6.3 Coordinated peroxisome turnover (pexophagy)

NIX-mediated pexophagy emerges as part of coordinated organelle remodeling under iron chelation and differentiation programs (wilhelm2022bnip3lnixregulatesboth pages 1-2, wilhelm2022bnip3lnixregulatesboth pages 3-4). Programmed peroxisome turnover was observed in primary human erythroid differentiation (PMP70 loss) (wilhelm2022bnip3lnixregulatesboth pages 10-11).

7) Recent developments (prioritize 2023–2024)

7.1 2023: MER–WIPI2 mechanism clarifies how NIX initiates mitophagy

Bunker et al. (EMBO J; published online Aug 2023; https://doi.org/10.15252/embj.2023113491) showed that the NIX MER binds and recruits WIPI2 to mitochondria and that robust mitophagy requires both MER and LIR (bunker2023nixinteractswith pages 1-2). This provides a mechanistic explanation for initiation steps beyond simple LC3 binding.

7.2 2023: FBXL4 identified as a central suppressor of receptor-mediated mitophagy

Multiple 2023 studies converge on FBXL4 as a negative regulator that restrains BNIP3/NIX by ubiquitin-mediated degradation. One study used a CRISPR/Cas9 E3 ligase screen targeting 606 E3 ligases and identified VHL and FBXL4 as top negative regulators of basal mitophagy (elcocks2023fbxl4ubiquitinligase pages 1-2). Another study directly demonstrates SCF(FBXL4) constitutively ubiquitylates/degrades NIX/BNIP3, and that disease-associated FBXL4 variants impair this suppression (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, nguyen‐dien2023fbxl4suppressesmitophagy pages 9-10).

7.3 2024: PPTC7 emerges as a mechanistic cofactor regulating BNIP3/NIX turnover

Nguyen-Dien et al. (EMBO Reports; Jul 2024; https://doi.org/10.1038/s44319-024-00181-y) identified specific residue-level interactions underpinning PPTC7 control of NIX turnover: ITC measured binding of PPTC7-D290N to an NIX peptide (35.9 ± 1.09, units as reported), and PPTC7 variants (e.g., Y179D) abolished binding, while NIX mutants disrupting the PPTC7-binding motif increased basal mitophagy (nguyendien2024pptc7antagonizesmitophagy pages 22-24). This provides unusually concrete quantitative evidence for a BNIP3L regulatory interface.

7.4 2024: pexophagy pharmacology via VHL inhibition and HIF-1α activation

Kim et al. (Molecules; published 18 Jan 2024; https://doi.org/10.3390/molecules29020482) report that the VHL inhibitor VH298 induces pexophagy in HeLa cells, requiring canonical autophagy (ATG5) and the pexophagy adaptor NBR1, and depending on HIF-1α transcriptional activity (silencing HIF-1α blocks the effect) (kim2024inhibitionofvhl pages 1-2, kim2024inhibitionofvhl pages 2-4). The paper discusses BNIP3L/NIX as a HIF-1α-upregulated mitophagy receptor and notes its reported role in pexophagy, positioning BNIP3L/NIX as a plausible downstream effector in HIF-driven organelle autophagy programs (kim2024inhibitionofvhl pages 6-8).

8) Current applications and real-world implementations

8.1 Experimental/biotech implementation: assays and models in current use

BNIP3L/NIX biology is operationalized using:

mt-mKeima mitophagy reporter with flow cytometry and confocal microscopy (used in FBXL4 pathway studies) (nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, elcocks2023fbxl4ubiquitinligase pages 9-10).
mito-QC / pexo-QC tandem fluorescent reporters to quantify delivery of mitochondria/peroxisomes to lysosomes (wilhelm2022bnip3lnixregulatesboth pages 1-2, wilhelm2022bnip3lnixregulatesboth pages 3-4).
CRISPR screens to discover regulators of basal mitophagy (e.g., E3 ligase screens) (elcocks2023fbxl4ubiquitinligase pages 1-2).
Quantitative binding assays (ITC) to resolve specific regulator–receptor interfaces (PPTC7–NIX) (nguyendien2024pptc7antagonizesmitophagy pages 22-24).

These are now standard toolkits for functional annotation and mechanistic dissection.

8.2 Pharmacologic modulation of BNIP3L/NIX pathways (research tools; therapeutic hypotheses)

MLN4924 (neddylation inhibitor; cullin-RING ligase inhibition): In RPE1 cells, MLN4924 increases BNIP3 and NIX levels and increases mitophagy measured by mt-mKeima flow cytometry, with statistical significance reported across multiple experiments (elcocks2023fbxl4ubiquitinligase pages 9-10). The work frames MLN4924 as a strong inducer of mitophagy and a candidate tool/agent for mitochondrial dysfunction contexts (elcocks2023fbxl4ubiquitinligase pages 1-2).
VHL inhibition (VH298) / HIF stabilization (roxadustat): VHL inhibition induces HIF-dependent pexophagy (ATG5- and NBR1-dependent), illustrating how hypoxia pathway modulation can drive selective organelle autophagy programs; BNIP3L/NIX is cited as part of hypoxia-driven receptor biology and pexophagy literature (kim2024inhibitionofvhl pages 1-2, kim2024inhibitionofvhl pages 6-8).

These interventions constitute “real-world implementations” primarily as research-enabled pathway modulation, rather than approved BNIP3L-targeted therapies.

8.3 Clinical trial landscape

A ClinicalTrials.gov search with “BNIP3L OR NIX AND mitophagy” did not yield a clearly relevant interventional trial specifically targeting BNIP3L/NIX in the retrieved clinical-trial output, suggesting no obvious BNIP3L/NIX-specific clinical program is captured by this query at present (kim2024inhibitionofvhl pages 1-2).

9) Expert opinions / authoritative synthesis (2024 perspective)

A 2024 Biochemical Society Transactions review emphasizes that BNIP3/NIX-mediated mitophagy requires careful spatiotemporal regulation, and highlights that identification of new negative regulators (FBXL4, PPTC7, TMEM11) indicates receptor-mediated mitophagy is actively suppressed under basal conditions to avoid pathological over-clearance of mitochondria (niemi2024coordinatingbnip3nixmediatedmitophagy pages 3-4, niemi2024coordinatingbnip3nixmediatedmitophagy pages 9-10). The same review emphasizes the severe consequences of dysregulation in animal models (perinatal lethality and metabolic dysfunction) and the link to human mitochondrial disease when turnover control fails (niemi2024coordinatingbnip3nixmediatedmitophagy pages 3-4).

10) Statistics and quantitative findings (from recent studies)

CRISPR screen size/design (2023): Screen of 606 E3 ubiquitin ligases (MOI 0.2; 1,000× coverage; four sgRNAs per gene; 243 non-targeting controls) identified VHL and FBXL4 as strongest negative regulators of basal mitophagy (elcocks2023fbxl4ubiquitinligase pages 1-2).
PPTC7–NIX binding (2024): ITC binding to an NIX peptide reported as 35.9 ± 1.09 for PPTC7-D290N (units as reported), with Y179D variant non-binding; NIX Arg147-centered motif required for binding and turnover, and NIX mutants increased basal mitophagy (nguyendien2024pptc7antagonizesmitophagy pages 22-24).
In vivo severity (2024): Fully penetrant perinatal lethality in Pptc7 knockout mice with metabolic defects (including hypoketotic hypoglycemia) underscores organismal importance of restricting BNIP3/NIX levels/mitophagy (wei2024duallocalizedpptc7limits pages 1-2).

11) Figures (visual evidence)

Key figure schematics from Niemi & Friedman (2024) illustrate (i) BNIP3/NIX domain architecture (LIR, MER, BH3, TM) and (ii) a regulatory model integrating FBXL4 and PPTC7 control of receptor abundance and TMEM11 spatial restriction of receptor-mediated mitophagy (niemi2024coordinatingbnip3nixmediatedmitophagy media af8c1d6a, niemi2024coordinatingbnip3nixmediatedmitophagy media c89f3902).

12) Summary of functional annotation (high-confidence)

Human BNIP3L (NIX; UniProt O60238) is a tail-anchored OMM selective-autophagy receptor whose primary role is to recruit autophagy machinery to mitochondria to execute receptor-mediated mitophagy, especially during programmed mitochondrial clearance in erythroid differentiation, and contributing to basal mitophagy. Mechanistically, it engages ATG8 proteins via a phosphorylation-regulated LIR and can recruit WIPI2 via an MER to promote robust mitophagy initiation/organization. Its abundance and activity are tightly controlled by hypoxia-driven transcription (HIF-1α; antagonized by VHL) and by ubiquitin/proteasome-mediated turnover via SCF(FBXL4) with PPTC7 as a critical regulator/cofactor; dysregulation is linked to mitochondrial disease phenotypes. BNIP3L/NIX can also localize to peroxisomes to promote pexophagy in defined contexts, underscoring a broader role in organelle quality control (bunker2023nixinteractswith pages 1-2, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, wilhelm2022bnip3lnixregulatesboth pages 1-2, nguyendien2024pptc7antagonizesmitophagy pages 22-24).

Embedded artifact

Category	Details
Identity/Localization	Human BNIP3L/NIX corresponds to BNIP3L (UniProt O60238), a BNIP3 paralog and single-pass C-terminal tail-anchored outer mitochondrial membrane (OMM) protein; most of the protein faces the cytosol, enabling recruitment of autophagy machinery. It is distinct from BNIP3, although the two share ~50–65% homology and overlapping receptor functions (niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, delgado2023theermembrane pages 1-2, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2).
Domains/Motifs	BNIP3L/NIX contains an atypical BH3-only region, a canonical LIR motif for ATG8-family binding, a minimal essential region (MER) important for mitophagy initiation, and a C-terminal transmembrane domain required for OMM targeting and dimerization. Phosphorylation of Ser34/Ser35 enhances autophagosomal recruitment; Ser212 is linked to monomer–dimer regulation (bunker2023nixinteractswith pages 1-2, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, marinkovic2021abriefoverview pages 2-3).
Core molecular function	Primary function is receptor-mediated selective autophagy of mitochondria (mitophagy), largely ubiquitin-independent at the receptor level: NIX binds LC3/GABARAP through its LIR and recruits upstream autophagy effectors through its MER. Recent work shows the MER binds WIPI2, while the LIR organizes WIPI2 into puncta for robust mitophagy; both LIR and MER are required for strong activity in CID/reconstitution-style assays (bunker2023nixinteractswith pages 1-2).
Key regulators (2023–2024)	FBXL4/SCF is a major negative regulator that constitutively ubiquitylates/degrades NIX and BNIP3 to suppress basal mitophagy; VHL restrains NIX indirectly by degrading HIF-1α, thereby limiting hypoxia/iron-chelation-induced transcription; PPTC7 promotes NIX/BNIP3 turnover and functionally cooperates with FBXL4; TMEM11 spatially restricts BNIP3/NIX-mediated mitophagy. Hypoxia or iron chelation elevates NIX via HIF-1α signaling (niemi2024coordinatingbnip3nixmediatedmitophagy pages 3-4, niemi2024coordinatingbnip3nixmediatedmitophagy pages 9-10, elcocks2023fbxl4ubiquitinligase pages 1-2, wei2024duallocalizedpptc7limits pages 1-2, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2).
Key partners	Direct/functional partners include LC3 and GABARAP family proteins, WIPI2, BCL2/Beclin-1 axis components, and the turnover machinery FBXL4 and PPTC7. NIX and BNIP3 can homo-/heterodimerize via their TM domains, and dimerization promotes receptor activity (bunker2023nixinteractswith pages 1-2, field2024theroleof pages 20-25, marinkovic2021abriefoverview pages 2-3, nguyendien2024pptc7antagonizesmitophagy pages 22-24).
Physiological roles	Best-established physiological role is programmed mitochondrial clearance during erythroid maturation/reticulocyte differentiation; Nix-null models show defective mitochondrial removal and impaired erythrocyte maturation. BNIP3/NIX also contribute to basal mitophagic flux, mitochondrial remodeling in differentiation contexts, and NIX can additionally mediate pexophagy, including during erythrocyte and cardiomyocyte differentiation (marinkovic2021abriefoverview pages 1-1, niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3, wilhelm2022bnip3lnixregulatesboth pages 10-11, wilhelm2022bnip3lnixregulatesboth pages 1-2).
Disease links/applications	Dysregulated NIX turnover is linked to FBXL4-associated mitochondrial DNA depletion syndrome (MTDPS13) and related mitochondrial disease biology. In ischemic brain models, stabilizing BNIP3L/NIX can restore mitophagy and improve injury phenotypes. In cancer and other stress contexts, NIX has context-dependent biomarker/target potential through effects on mitophagy, oxidative stress handling, and survival. MLN4924 is reported as a strong mitophagy inducer via cullin-RING ligase inhibition, making BNIP3L/NIX regulatory pathways experimentally and potentially therapeutically actionable (elcocks2023fbxl4ubiquitinligase pages 1-2, nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2, wei2024duallocalizedpptc7limits pages 1-2).
Key quantitative data	Quantitative findings from recent studies include: CRISPR screen of 606 E3 ubiquitin ligases identified VHL and FBXL4 as strongest negative regulators of basal mitophagy; screen used MOI 0.2, 1,000× coverage, 4 sgRNAs/gene, and 243 non-targeting controls (elcocks2023fbxl4ubiquitinligase pages 1-2). In the PPTC7 study, ITC measured binding of PPTC7-D290N to a NIX peptide at 35.9 ± 1.09 (units as reported), while a Y179D variant was non-binding; NIX mutants disrupting the PPTC7-binding motif increased basal mitophagy by Keima imaging (nguyendien2024pptc7antagonizesmitophagy pages 22-24). Pptc7 KO mice showed fully penetrant perinatal lethality with metabolic defects, highlighting physiologic importance of restraining NIX/BNIP3 signaling (wei2024duallocalizedpptc7limits pages 1-2).

Table: This table condenses the main functional annotation points for human BNIP3L/NIX, including identity, mechanism, regulators, partners, physiology, and translational relevance. It emphasizes 2023–2024 advances such as FBXL4-, VHL/HIF1α-, PPTC7-, and WIPI2-related regulation with supporting context-ID citations.

References

(niemi2024coordinatingbnip3nixmediatedmitophagy pages 1-3): Natalie M. Niemi and Jonathan R. Friedman. Coordinating bnip3/nix-mediated mitophagy in space and time. Biochemical Society Transactions, 52:1969-1979, Oct 2024. URL: https://doi.org/10.1042/bst20221364, doi:10.1042/bst20221364. This article has 32 citations and is from a peer-reviewed journal.
(nguyen‐dien2023fbxl4suppressesmitophagy pages 1-2): Giang Thanh Nguyen‐Dien, Keri‐Lyn Kozul, Yi Cui, Brendan Townsend, Prajakta Gosavi Kulkarni, Soo Siang Ooi, Antonio Marzio, Nissa Carrodus, Steven Zuryn, Michele Pagano, Robert G Parton, Michael Lazarou, S Sean Millard, Robert W Taylor, Brett M Collins, Mathew JK Jones, and Julia K Pagan. fbxl4 suppresses mitophagy by restricting the accumulation of nix and bnip3 mitophagy receptors. The EMBO Journal, May 2023. URL: https://doi.org/10.15252/embj.2022112767, doi:10.15252/embj.2022112767. This article has 85 citations.
(marinkovic2021abriefoverview pages 1-1): Mija Marinković and Ivana Novak. A brief overview of bnip3l/nix receptor‐mediated mitophagy. FEBS Open Bio, 11:3230-3236, Oct 2021. URL: https://doi.org/10.1002/2211-5463.13307, doi:10.1002/2211-5463.13307. This article has 80 citations and is from a peer-reviewed journal.
(delgado2023theermembrane pages 1-2): Jose M Delgado, Logan Wallace Shepard, Sarah W Lamson, Samantha L Liu, and Christopher J Shoemaker. The er membrane protein complex restricts mitophagy by controlling bnip3 turnover. The EMBO Journal, 43:32-60, Dec 2023. URL: https://doi.org/10.1038/s44318-023-00006-z, doi:10.1038/s44318-023-00006-z. This article has 25 citations.
(bunker2023nixinteractswith pages 1-2): Eric N Bunker, François Le Guerroué, Chunxin Wang, Marie‐Paule Strub, Achim Werner, Nico Tjandra, and Richard J Youle. Nix interacts with wipi2 to induce mitophagy. The EMBO Journal, Aug 2023. URL: https://doi.org/10.15252/embj.2023113491, doi:10.15252/embj.2023113491. This article has 45 citations.
(marinkovic2021abriefoverview pages 2-3): Mija Marinković and Ivana Novak. A brief overview of bnip3l/nix receptor‐mediated mitophagy. FEBS Open Bio, 11:3230-3236, Oct 2021. URL: https://doi.org/10.1002/2211-5463.13307, doi:10.1002/2211-5463.13307. This article has 80 citations and is from a peer-reviewed journal.
(field2024theroleof pages 20-25): J Field. The role of nix in calcium signaling, gene expression, and oxidative phenotype of skeletal muscle. Unknown journal, 2024.
(wilhelm2022bnip3lnixregulatesboth pages 1-2): Léa P Wilhelm, Juan Zapata‐Muñoz, Beatriz Villarejo‐Zori, Stephanie Pellegrin, Catarina Martins Freire, Ashley M Toye, Patricia Boya, and Ian G Ganley. Bnip3l/nix regulates both mitophagy and pexophagy. The EMBO Journal, Oct 2022. URL: https://doi.org/10.15252/embj.2022111115, doi:10.15252/embj.2022111115. This article has 112 citations.
(wilhelm2022bnip3lnixregulatesboth pages 10-11): Léa P Wilhelm, Juan Zapata‐Muñoz, Beatriz Villarejo‐Zori, Stephanie Pellegrin, Catarina Martins Freire, Ashley M Toye, Patricia Boya, and Ian G Ganley. Bnip3l/nix regulates both mitophagy and pexophagy. The EMBO Journal, Oct 2022. URL: https://doi.org/10.15252/embj.2022111115, doi:10.15252/embj.2022111115. This article has 112 citations.
(wilhelm2022bnip3lnixregulatesboth pages 7-9): Léa P Wilhelm, Juan Zapata‐Muñoz, Beatriz Villarejo‐Zori, Stephanie Pellegrin, Catarina Martins Freire, Ashley M Toye, Patricia Boya, and Ian G Ganley. Bnip3l/nix regulates both mitophagy and pexophagy. The EMBO Journal, Oct 2022. URL: https://doi.org/10.15252/embj.2022111115, doi:10.15252/embj.2022111115. This article has 112 citations.
(elcocks2023fbxl4ubiquitinligase pages 1-2): Hannah Elcocks, Ailbhe J Brazel, Katy R McCarron, Manuel Kaulich, Koraljka Husnjak, Heather Mortiboys, Michael J Clague, and Sylvie Urbé. Fbxl4 ubiquitin ligase deficiency promotes mitophagy by elevating nix levels. The EMBO Journal, Apr 2023. URL: https://doi.org/10.15252/embj.2022112799, doi:10.15252/embj.2022112799. This article has 61 citations.
(nguyen‐dien2023fbxl4suppressesmitophagy pages 9-10): Giang Thanh Nguyen‐Dien, Keri‐Lyn Kozul, Yi Cui, Brendan Townsend, Prajakta Gosavi Kulkarni, Soo Siang Ooi, Antonio Marzio, Nissa Carrodus, Steven Zuryn, Michele Pagano, Robert G Parton, Michael Lazarou, S Sean Millard, Robert W Taylor, Brett M Collins, Mathew JK Jones, and Julia K Pagan. fbxl4 suppresses mitophagy by restricting the accumulation of nix and bnip3 mitophagy receptors. The EMBO Journal, May 2023. URL: https://doi.org/10.15252/embj.2022112767, doi:10.15252/embj.2022112767. This article has 85 citations.
(wei2024duallocalizedpptc7limits pages 1-2): Lianjie Wei, Mehmet Oguz Gok, Jordyn D Svoboda, Keri-Lyn Kozul, Merima Forny, Jonathan R Friedman, and Natalie M Niemi. Dual-localized pptc7 limits mitophagy through proximal and dynamic interactions with bnip3 and nix. Life Science Alliance, 7:e202402765, Jul 2024. URL: https://doi.org/10.26508/lsa.202402765, doi:10.26508/lsa.202402765. This article has 17 citations and is from a peer-reviewed journal.
(nguyendien2024pptc7antagonizesmitophagy pages 22-24): Giang Thanh Nguyen-Dien, Brendan Townsend, Prajakta Gosavi Kulkarni, Keri-Lyn Kozul, Soo Siang Ooi, Denaye N Eldershaw, Saroja Weeratunga, Meihan Liu, Mathew JK Jones, S Sean Millard, Dominic CH Ng, Michele Pagano, Alexis Bonfim-Melo, Tobias Schneider, David Komander, Michael Lazarou, Brett M Collins, and Julia K Pagan. Pptc7 antagonizes mitophagy by promoting bnip3 and nix degradation via scffbxl4. EMBO Reports, 25:3324-3347, Jul 2024. URL: https://doi.org/10.1038/s44319-024-00181-y, doi:10.1038/s44319-024-00181-y. This article has 22 citations and is from a highest quality peer-reviewed journal.
(wilhelm2022bnip3lnixregulatesboth pages 3-4): Léa P Wilhelm, Juan Zapata‐Muñoz, Beatriz Villarejo‐Zori, Stephanie Pellegrin, Catarina Martins Freire, Ashley M Toye, Patricia Boya, and Ian G Ganley. Bnip3l/nix regulates both mitophagy and pexophagy. The EMBO Journal, Oct 2022. URL: https://doi.org/10.15252/embj.2022111115, doi:10.15252/embj.2022111115. This article has 112 citations.
(kim2024inhibitionofvhl pages 1-2): Yong Hwan Kim, Na Yeon Park, Doo Sin Jo, Ji-Eun Bae, Joon Bum Kim, Kyuhee Park, Kwiwan Jeong, Pansoo Kim, Eunbyul Yeom, and Dong-Hyung Cho. Inhibition of vhl by vh298 accelerates pexophagy by activation of hif-1α in hela cells. Molecules, 29:482, Jan 2024. URL: https://doi.org/10.3390/molecules29020482, doi:10.3390/molecules29020482. This article has 0 citations.
(kim2024inhibitionofvhl pages 2-4): Yong Hwan Kim, Na Yeon Park, Doo Sin Jo, Ji-Eun Bae, Joon Bum Kim, Kyuhee Park, Kwiwan Jeong, Pansoo Kim, Eunbyul Yeom, and Dong-Hyung Cho. Inhibition of vhl by vh298 accelerates pexophagy by activation of hif-1α in hela cells. Molecules, 29:482, Jan 2024. URL: https://doi.org/10.3390/molecules29020482, doi:10.3390/molecules29020482. This article has 0 citations.
(kim2024inhibitionofvhl pages 6-8): Yong Hwan Kim, Na Yeon Park, Doo Sin Jo, Ji-Eun Bae, Joon Bum Kim, Kyuhee Park, Kwiwan Jeong, Pansoo Kim, Eunbyul Yeom, and Dong-Hyung Cho. Inhibition of vhl by vh298 accelerates pexophagy by activation of hif-1α in hela cells. Molecules, 29:482, Jan 2024. URL: https://doi.org/10.3390/molecules29020482, doi:10.3390/molecules29020482. This article has 0 citations.
(elcocks2023fbxl4ubiquitinligase pages 9-10): Hannah Elcocks, Ailbhe J Brazel, Katy R McCarron, Manuel Kaulich, Koraljka Husnjak, Heather Mortiboys, Michael J Clague, and Sylvie Urbé. Fbxl4 ubiquitin ligase deficiency promotes mitophagy by elevating nix levels. The EMBO Journal, Apr 2023. URL: https://doi.org/10.15252/embj.2022112799, doi:10.15252/embj.2022112799. This article has 61 citations.
(niemi2024coordinatingbnip3nixmediatedmitophagy pages 3-4): Natalie M. Niemi and Jonathan R. Friedman. Coordinating bnip3/nix-mediated mitophagy in space and time. Biochemical Society Transactions, 52:1969-1979, Oct 2024. URL: https://doi.org/10.1042/bst20221364, doi:10.1042/bst20221364. This article has 32 citations and is from a peer-reviewed journal.
(niemi2024coordinatingbnip3nixmediatedmitophagy pages 9-10): Natalie M. Niemi and Jonathan R. Friedman. Coordinating bnip3/nix-mediated mitophagy in space and time. Biochemical Society Transactions, 52:1969-1979, Oct 2024. URL: https://doi.org/10.1042/bst20221364, doi:10.1042/bst20221364. This article has 32 citations and is from a peer-reviewed journal.
(niemi2024coordinatingbnip3nixmediatedmitophagy media af8c1d6a): Natalie M. Niemi and Jonathan R. Friedman. Coordinating bnip3/nix-mediated mitophagy in space and time. Biochemical Society Transactions, 52:1969-1979, Oct 2024. URL: https://doi.org/10.1042/bst20221364, doi:10.1042/bst20221364. This article has 32 citations and is from a peer-reviewed journal.
(niemi2024coordinatingbnip3nixmediatedmitophagy media c89f3902): Natalie M. Niemi and Jonathan R. Friedman. Coordinating bnip3/nix-mediated mitophagy in space and time. Biochemical Society Transactions, 52:1969-1979, Oct 2024. URL: https://doi.org/10.1042/bst20221364, doi:10.1042/bst20221364. This article has 32 citations and is from a peer-reviewed journal.

Artifacts

Edison artifact artifact-00

Citations

bunker2023nixinteractswith pages 1-2
field2024theroleof pages 20-25
marinkovic2021abriefoverview pages 2-3
kim2024inhibitionofvhl pages 6-8
kim2024inhibitionofvhl pages 1-2
marinkovic2021abriefoverview pages 1-1
delgado2023theermembrane pages 1-2
kim2024inhibitionofvhl pages 2-4
https://doi.org/10.15252/embj.2023113491
https://doi.org/10.1038/s44319-024-00181-y
https://doi.org/10.3390/molecules29020482
https://doi.org/10.1042/bst20221364,
https://doi.org/10.15252/embj.2022112767,
https://doi.org/10.1002/2211-5463.13307,
https://doi.org/10.1038/s44318-023-00006-z,
https://doi.org/10.15252/embj.2023113491,
https://doi.org/10.15252/embj.2022111115,
https://doi.org/10.15252/embj.2022112799,
https://doi.org/10.26508/lsa.202402765,
https://doi.org/10.1038/s44319-024-00181-y,
https://doi.org/10.3390/molecules29020482,

📚 Additional Documentation

Notes

(BNIP3L-notes.md)

BNIP3L (NIX) curation notes

UniProt: O60238 (BNI3L_HUMAN). Synonyms: BNIP3A, BNIP3H, NIX, B5, NIP3L, BNIP3alpha.
219 aa, single-pass tail-anchored membrane protein. C-terminal transmembrane domain (FT TRANSMEM 188..208),
BH3 motif (FT MOTIF 126..148), large N-terminal disordered region (1..101).

Core function synthesis

BNIP3L/NIX is an outer-mitochondrial-membrane, tail-anchored, atypical BH3-containing member of the
BNIP3/NIP3 family. Its best-supported, conserved function is as a selective autophagy (mitophagy)
receptor: it is anchored in the mitochondrial outer membrane via its C-terminal TM domain with the
N-terminus facing the cytosol, where an LIR (LC3-interacting region) motif binds the Atg8-family proteins
LC3 and GABARAP/GABARAPL1/GABARAPL2, tethering mitochondria to the forming autophagosome. This drives
programmed clearance of mitochondria, most strikingly during terminal erythroid/reticulocyte maturation,
and also during developmentally programmed and stress-induced mitochondrial turnover.

PMID:20200478

The UniProt IntAct interaction table directly records NIX binding to the human Atg8 orthologs GABARAPL1
(Q9H0R8), GABARAPL2 (P60520) and yeast ATG8 (P38182, Xeno), consistent with the LIR-dependent receptor model
(see BNIP3L-uniprot.txt INTERACTION block).

Historically NIX/BNIP3L was first described as a pro-apoptotic BCL-2/NIP3-family protein, but this is
context-dependent and atypical: NIX and BNIP3 do not act through classical cytochrome-c/caspase apoptosis.

PMID:9973195

PMID:21264228

Notably, the original "B5"/BNIP3L paper found it does NOT itself induce apoptosis but rather inhibits
Nip3(BNIP3)-induced apoptosis, and localized it to nuclear envelope, ER and mitochondria:

PMID:10381623

This explains why both positive and negative regulation of apoptosis annotations exist in GOA; the
apoptotic role is genuine but secondary/contextual and direction-dependent, and is best treated as
non-core relative to mitophagy.

Hypoxia / autophagy (survival)

Under hypoxia, HIF induces BNIP3 and BNIP3L; together they promote (macro)autophagy as a survival
mechanism, via their atypical BH3 domains disrupting the Bcl-2-Beclin1 complex, WITHOUT inducing cell death.

PMID:19273585

Note: the GOA IGI annotations to "negative regulation of programmed cell death", "positive regulation of
macroautophagy" and "cellular response to hypoxia" all trace to PMID:19273585 and are well supported.

Mitochondrial quality control via SPATA18/MIEAP (MALM)

NIX interacts (via its BH3 domain) with SPATA18/Mieap (via coiled-coil) at the mitochondrial outer
membrane, in a ROS-dependent manner, and is required for MALM (Mieap-induced accumulation of lysosome-like
organelles within mitochondria), a non-canonical mitochondrial protein degradation/quality-control process.

PMID:21264228

This is the source of the GOA "mitochondrial protein catabolic process" (GO:0035694, IMP) and
"mitochondrial outer membrane" (GO:0005741, IMP) annotations.

Viral hijacking of NIX-mediated mitophagy (defense response to virus)

Multiple viruses hijack NIX-mediated mitophagy. SARS-CoV-2 ORF10 binds NIX (and LC3B) to drive mitophagy
and degrade MAVS, suppressing innate immunity; KSHV vIRF-1 likewise activates NIX-mediated mitophagy.

PMID:34845370

The GOA "defense response to virus" (GO:0051607, IDA, PMID:9973195) actually traces to the 1999 BNIP3alpha
paper, which is about apoptosis/anti-apoptosis-protein interaction, not antiviral defense per se; the
modern antiviral connection is via mitophagy/MAVS turnover (PMID:34845370). The original PMID:9973195 does
not provide direct "defense response to virus" evidence, so that annotation is weakly supported by its
cited reference.

Localization

UniProt subcellular location: Nucleus envelope; Endoplasmic reticulum; Mitochondrion outer membrane;
Membrane (single-pass). Colocalizes with SPATA18 at the mitochondrion outer membrane.
[file:human/BNIP3L/BNIP3L-uniprot.txt "SUBCELLULAR LOCATION: Nucleus envelope. Endoplasmic reticulum. Mitochondrion outer membrane. Membrane"]

The mitochondrial outer membrane is the core functional location. ER localization is reported (and linked
to Ca2+ handling in the Mieap-paper introduction) but is secondary. Nuclear envelope/lamin binding derives
from the original B5/PMID:10381623 study; nucleus / nuclear speck / nuclear envelope annotations are
weakly supported, likely reflecting the disordered N-terminus and the tail-anchor insertion behaviour, and
are not the core functional compartment for the mitophagy receptor role.

Protein binding annotations

Numerous GO:0005515 "protein binding" and GO:0042802 "identical protein binding" IPI annotations come from
high-throughput interactome papers (16189514, 19060904, 21516116, 25416956, 25910212, 27107012, 28514442,
31515488, 32296183, 33961781, 24981860) and specific studies. "protein binding" is uninformative and is
marked as over-annotated. "identical protein binding"/homodimerization is genuine and informative (NIX
self-associates; UniProt: "Self-associates", IntAct O60238-O60238 NbExp=11; PMID:10381623 reports it
"binds... itself"); homodimerization is retained.

PMID:10381623: NIX(B5) binds itself and Nip3/BNIP3 -> homodimerization / heterodimerization with BNIP3.
PMID:22645275: ATP13A2 interactome (α-synuclein) - generic.
PMID:24316735: TR3/NR4A1 (Nup4A1) autophagic cell death - NIX listed; the UniProt IntAct table records O60238-NR4A1.
PMID:34845370: SARS-CoV-2 ORF10 (defense/mitophagy, informative for antiviral mitophagy not generic binding).
PMID:21264221, 21264228: Mieap/SPATA18 (mitochondrial QC).

Key existing annotation classification summary

CORE (mitophagy receptor / selective autophagy of mitochondria):
- regulation of mitophagy (GO:1901524)
- mitochondrial outer membrane (GO:0005741) localization
- positive regulation of macroautophagy (GO:0016239)
- regulation of protein localization to mitochondrion (GO:1903747)

SECONDARY / NON-CORE:
- apoptosis (positive and negative regulation), mitochondrial fragmentation in apoptosis
- cellular response to hypoxia, negative regulation of programmed cell death
- mitochondrial protein catabolic process (MALM / Mieap)
- defense response to virus
- mitochondrial membrane potential / permeability
- ER, nucleus, nuclear envelope, nuclear speck localizations (secondary/weak)

OVER-ANNOTATED / UNINFORMATIVE:
- protein binding (GO:0005515) - all instances

Proposed new term

NIX/BNIP3L's defining molecular activity (LIR-dependent Atg8/LC3 binding as a mitophagy receptor) is not
captured by any existing annotation. Candidate: GO:0098780 "response to mitochondrial depolarisation" or
more precisely the molecular function for selective autophagy receptor activity. The most appropriate
existing molecular-function term is GO:0140311 "protein sequestering activity"? No — the canonical term is
mitophagy receptor activity. Existing process term GO:0000423 "mitophagy" (in UniProt DR but not in GOA
seeded set) and GO:1905037 "autophagosome organization" are relevant. I propose adding the molecular
function for the cargo-receptor/Atg8-binding role.

Falcon deep research findings (2026-06-07)

The Falcon report (BNIP3L-deep-research-falcon.md) reinforces the established mitophagy-receptor core
already in the review, and adds several mechanistic/regulatory findings (mostly 2022-2024) not previously
captured. PMIDs below were resolved from the report DOIs via PubMed and verified by title.

CONFIRMS (core): NIX is an OMM tail-anchored selective-autophagy (mitophagy) receptor that engages
ATG8/LC3-GABARAP via its LIR and is central to programmed mitochondrial clearance in erythroid
maturation; also contributes to basal mitophagy. Consistent with existing GO:1901524 / GO:0005741 /
PMID:20200478 annotations. [PMID:39377319 Niemi & Friedman 2024 review "Coordinating BNIP3/NIX-mediated
mitophagy in space and time"]; [PMID:34597467 Marinkovic & Novak 2021 review].
NEW (mechanism — initiation beyond LC3 binding): Beyond the LIR, NIX has a minimal essential region
(MER) that binds and recruits the autophagy effector WIPI2 to mitochondria; both LIR and MER are
required for robust mitophagy, and the LIR reorganizes WIPI2 into puncta even without ATG8s. This
places NIX-driven initiation downstream of canonical initiation complexes. [PMID:37621214 Bunker et al.
2023 "Nix interacts with WIPI2 to induce mitophagy", EMBO J].
NEW (negative regulation — receptor turnover): SCF(FBXL4) localizes to the OMM in unstressed cells and
constitutively ubiquitylates/degrades NIX and BNIP3 to suppress basal mitophagy; an independent CRISPR
screen of 606 E3 ligases identified VHL and FBXL4 as the strongest negative regulators of basal
mitophagy (VHL acts indirectly by limiting HIF-1alpha-driven transcription of NIX/BNIP3; FBXL4 acts
post-translationally). Pathogenic FBXL4 variants fail to degrade NIX/BNIP3, linking dysregulated NIX
turnover to FBXL4-associated mtDNA depletion syndrome (MTDPS13 / mitochondrial encephalomyopathy).
[PMID:37161784 Nguyen-Dien et al. 2023 "FBXL4 suppresses mitophagy by restricting the accumulation of
NIX and BNIP3 mitophagy receptors", EMBO J]; [PMID:37102372 Elcocks et al. 2023 "FBXL4 ubiquitin ligase
deficiency promotes mitophagy by elevating NIX levels", EMBO J]. The neddylation inhibitor MLN4924
(cullin-RING ligase inhibition) elevates NIX/BNIP3 and strongly induces mitophagy (research tool).
NEW (negative regulation — cofactor): The mitochondrial phosphatase PPTC7 is an essential cofactor for
SCF(FBXL4)-mediated turnover of BNIP3/NIX. A dual-localized (matrix + OMM) pool of PPTC7 acts as an
adaptor linking BNIP3/NIX to FBXL4; this turnover function is independent of PPTC7 catalytic
(phosphatase) activity in one study, and an NIX motif (Arg147-centered) is required for PPTC7 binding.
Pptc7-KO mice show fully penetrant perinatal lethality with metabolic defects. [PMID:38991726 Wei et al.
2024 "Dual-localized PPTC7 limits mitophagy through proximal and dynamic interactions with BNIP3 and
NIX", Life Sci Alliance]; [PMID:38992176 Nguyen-Dien et al. 2024 "PPTC7 antagonizes mitophagy by
promoting BNIP3 and NIX degradation via SCF", EMBO Rep].
NEW (second cargo — pexophagy): NIX is not restricted to mitochondria; it independently localizes to
peroxisomes and drives pexophagy (selective peroxisome autophagy), e.g. under iron chelation and during
cardiomyocyte/erythrocyte differentiation; Nix-null mouse tissue has higher peroxisomal content. This
broadens NIX cargo selectivity beyond mitochondria and is not represented in the current annotation set.
[PMID:36215693 Wilhelm et al. 2022 "BNIP3L/NIX regulates both mitophagy and pexophagy", EMBO J].
PROVISIONAL / context (do NOT use to change annotations): phosphoregulation of NIX activity
(Ser34/Ser35 near the LIR enhancing autophagosome recruitment; C-terminal Ser212 tied to monomer-dimer
equilibrium) and TM-domain dimerization are cited from a 2021 review (PMID:34597467) without primary
residue-level data in the report; TMEM11 as a spatial restrictor of BNIP3/NIX mitophagy is mentioned in
the 2024 review (PMID:39377319) but not primary here. A VHL-inhibitor (VH298) pexophagy study
(Kim et al. 2024, Molecules, doi:10.3390/molecules29020482; 0 citations at time of report) is
NBR1/ATG5/HIF-1alpha-dependent and only positions NIX as a plausible downstream effector — treat as
low-confidence/peripheral. The "field2024 role of NIX in calcium/skeletal muscle" item has no resolvable
journal/PMID and is not used.

Net: the most material, citable NEW additions are the receptor-turnover axis (FBXL4/PPTC7; PMID:37161784,
37102372, 38991726, 38992176), the WIPI2/MER initiation mechanism (PMID:37621214), and pexophagy
(PMID:36215693). These augment but do not contradict any existing annotation action.

Pn Notes

(BNIP3L-pn-notes.md)

BNIP3L PN Consistency Notes

Generated: 2026-06-18
Project: PROTEOSTASIS
Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
UniProt: O60238
AIGR review status: COMPLETE
Review batch: proteostasis-batch-2026-06-06
Batch change status: added

Source Files Checked

AIGR review YAML: present - genes/human/BNIP3L/BNIP3L-ai-review.yaml
AIGR review HTML: present - genes/human/BNIP3L/BNIP3L-ai-review.html
Gene notes: present - genes/human/BNIP3L/BNIP3L-notes.md
GOA TSV: present - genes/human/BNIP3L/BNIP3L-goa.tsv
UniProt record: present - genes/human/BNIP3L/BNIP3L-uniprot.txt
PN dossier: projects/PROTEOSTASIS/reports/phase1_dossiers/BNIP3L.md
PN consistency section: projects/PROTEOSTASIS/reports/phase1_dossiers/_sections/BNIP3L.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/BNIP3L/BNIP3L-deep-research-falcon.md

AIGR Review Snapshot

Description: BNIP3L (NIX) is a tail-anchored, atypical BH3-containing member of the BNIP3/NIP3 family that is inserted into the mitochondrial outer membrane via its C-terminal transmembrane helix, with its N-terminal disordered region facing the cytosol. Its principal, conserved function is as a selective autophagy (mitophagy) receptor: an LC3-interacting region in the cytosolic domain binds Atg8-family proteins (LC3 and GABARAP/GABARAPL1/GABARAPL2), tethering mitochondria to the forming autophagosome and driving their programmed autophagic clearance. This is most prominent during terminal erythroid/reticulocyte maturation and other developmentally programmed or stress-induced episodes of mitochondrial turnover. NIX also participates in non-canonical mitochondrial quality control through ROS-dependent interaction with SPATA18/MIEAP, and under hypoxia it is induced by HIF and promotes pro-survival macroautophagy via its atypical BH3 domain. Although first described as a pro-apoptotic BCL-2-family protein, its effects on cell death are context-dependent and direction-dependent (it can both promote and inhibit cell death) and act largely through mitochondrial membrane permeability/necrosis rather than classical cytochrome-c/caspase apoptosis. Beyond mitochondria, NIX can independently localize to peroxisomes and act as a selective autophagy receptor for their clearance (pexophagy), broadening its cargo selectivity. NIX abundance is held in check by constitutive ubiquitin-mediated turnover: an SCF(FBXL4) ubiquitin ligase complex at the mitochondrial outer membrane, with the phosphatase PPTC7 as a cofactor, degrades NIX (and BNIP3) to restrain basal mitophagy, while hypoxia/HIF signaling induces NIX transcription. NIX is also exploited by several viruses, which hijack NIX-mediated mitophagy to degrade mitochondrial antiviral signaling components.
Existing/core annotation action counts: ACCEPT: 15; KEEP_AS_NON_CORE: 23; MARK_AS_OVER_ANNOTATED: 23; MODIFY: 1; REMOVE: 1

PN Consistency Summary

Consistency: Consistent. PN (mitophagy receptor + BECN1-availability modulator via atypical BH3), the review, notes and Falcon deep research all agree: NIX is an OMM tail-anchored mitophagy receptor (LIR→LC3/GABARAP; PMID:20200478) that under hypoxia also promotes pro-survival macroautophagy by disrupting Bcl-2-Beclin1 (PMID:19273585). PN row 1 = review core (mitophagy); PN row 2 = review's hypoxia/BECN1 axis. No contradictions.
PN story / NEW pressure: PN row-1 GO:0000423 mitophagy is correctly "supported_by_goa_regulation" — the review carries GO:1901524 regulation of mitophagy (ACCEPT, IEA) so the process is already captured. The genuine NEW pressure is the MF: the review proposes a new term "mitophagy receptor activity" claiming none exists. This is incorrect — GO:0140580 "mitochondrion autophagosome adaptor activity" already exists (def "binding activity of a molecule that brings together a mitochondrial membrane and an autophagosome during mitophagy"), exactly the LIR-tethering activity. So the MF is already captured by a real term; ADD GO:0140580 rather than a new term. BECN1-modulator (class III PI3K) row is correctly context_only (NIX modulates, is not a complex subunit).
Evidence alignment: PN cites review-style titles (Marinkovic FEBS Open Bio 2021; hypoxia BH3 paper = PMID:19273585; mitophagy-initiation BST review). Review uses PMID:20200478, 19273585, 21264228, 9973195, plus FBXL4/PPTC7 turnover refs. Strong overlap on the hypoxia and receptor papers.
Verdict: Consistent; mitophagy process already captured. Key finding: the review's proposed NEW "mitophagy receptor activity" term duplicates the existing GO:0140580. Recommended edits: [YAML][REF] replace the BNIP3L proposed_new_term "mitophagy receptor activity" with the existing GO:0140580 mitochondrion autophagosome adaptor activity (add as core MF, supported by PMID:20200478).

Full Consistency Review

UniProt: O60238 · batch: proteostasis-batch-2026-06-06 · review status: COMPLETE
PN placement: two rows — Autophagy-Lysosome Pathway|Autophagy substrate selection|Selective autophagy receptor|Mitophagy and ...|Autophagophore initiation and elongation|Class 3 PI3K complex 1, direct|Modulator of class 3 PI3K complex 1 activity|Modulator of BECN1 availability ; PN-node mapping: Mitophagy type → mapped/ok GO:0000423 mitophagy (goa_status=supported_by_goa_regulation); BECN1-modulator path → context_only/too_broad GO:0035032 (class III PI3K complex), class → context_only GO:0016236.
Consistency: Consistent. PN (mitophagy receptor + BECN1-availability modulator via atypical BH3), the review, notes and Falcon deep research all agree: NIX is an OMM tail-anchored mitophagy receptor (LIR→LC3/GABARAP; PMID:20200478) that under hypoxia also promotes pro-survival macroautophagy by disrupting Bcl-2-Beclin1 (PMID:19273585). PN row 1 = review core (mitophagy); PN row 2 = review's hypoxia/BECN1 axis. No contradictions.
PN story / NEW pressure: PN row-1 GO:0000423 mitophagy is correctly "supported_by_goa_regulation" — the review carries GO:1901524 regulation of mitophagy (ACCEPT, IEA) so the process is already captured. The genuine NEW pressure is the MF: the review proposes a new term "mitophagy receptor activity" claiming none exists. This is incorrect — GO:0140580 "mitochondrion autophagosome adaptor activity" already exists (def "binding activity of a molecule that brings together a mitochondrial membrane and an autophagosome during mitophagy"), exactly the LIR-tethering activity. So the MF is already captured by a real term; ADD GO:0140580 rather than a new term. BECN1-modulator (class III PI3K) row is correctly context_only (NIX modulates, is not a complex subunit).
Mapping strategy: Row-1 mitophagy projection is fine (already in GOA via regulation term). Row-2 context_only/too_broad for GO:0035032 is correct (do not assign complex membership to a modulator) — consistent with the rejected-broader precedent.
Evidence alignment: PN cites review-style titles (Marinkovic FEBS Open Bio 2021; hypoxia BH3 paper = PMID:19273585; mitophagy-initiation BST review). Review uses PMID:20200478, 19273585, 21264228, 9973195, plus FBXL4/PPTC7 turnover refs. Strong overlap on the hypoxia and receptor papers.
Verdict: Consistent; mitophagy process already captured. Key finding: the review's proposed NEW "mitophagy receptor activity" term duplicates the existing GO:0140580. Recommended edits: [YAML][REF] replace the BNIP3L proposed_new_term "mitophagy receptor activity" with the existing GO:0140580 mitochondrion autophagosome adaptor activity (add as core MF, supported by PMID:20200478).

PN Dossier Context

review_batch: proteostasis-batch-2026-06-06
review_yaml: genes/human/BNIP3L/BNIP3L-ai-review.yaml
PN workbook rows: 2

PN row 1: Autophagy-Lysosome Pathway | Autophagophore initiation and elongation | Class 3 PI3K complex 1, direct | Modulator of class 3 PI3K complex 1 activity | Modulator of BECN1 availability

UniProt: O60238
In branches: ALP
Notes: Mitochondrial membrane protein. Inhibits RHEB, also releases BECN1 from complexes with Bcl2 or BclXL. Also is a receptor for mitophagy by binding to LC3 through an LIR domain and enhances autophagy in response to hypoxia.
PN references (titles):
- Atypical BH3-domains of BNIP3 and BNIP3L lead to autophagy in hypoxia (tandfonline.com)
- A brief overview of BNIP3L/NIX receptor‐mediated mitophagy - Marinković - 2021 - FEBS Open Bio - Wiley Online Library
- The dynamics of mitochondrial autophagy at the initiation stage | Biochemical Society Transactions | Portland Press
PN-node mapping records (path + ancestors):
- [subtype] Autophagy-Lysosome Pathway|Autophagophore initiation and elongation|Class 3 PI3K complex 1, direct|Modulator of class 3 PI3K complex 1 activity|Modulator of BECN1 availability
  status=context_only scope=too_broad_to_propagate GO=[GO:0035032 phosphatidylinositol 3-kinase complex, class III]
  rationale: Reviewed as a class-III PI3K complex context or regulator bucket. This node is useful for curator interpretation, but it should not project cellular-component membership; only explicit complex-component leaves propagate to GO complex terms.
- [type] Autophagy-Lysosome Pathway|Autophagophore initiation and elongation|Class 3 PI3K complex 1, direct|Modulator of class 3 PI3K complex 1 activity
  status=context_only scope=too_broad_to_propagate GO=[GO:0035032 phosphatidylinositol 3-kinase complex, class III]
  rationale: Reviewed as a class-III PI3K complex context or regulator bucket. This node is useful for curator interpretation, but it should not project cellular-component membership; only explicit complex-component leaves propagate to GO complex terms.
- [group] Autophagy-Lysosome Pathway|Autophagophore initiation and elongation|Class 3 PI3K complex 1, direct
  status=context_only scope=too_broad_to_propagate GO=[GO:0035032 phosphatidylinositol 3-kinase complex, class III]
  rationale: Reviewed as a class-III PI3K complex context or regulator bucket. This node is useful for curator interpretation, but it should not project cellular-component membership; only explicit complex-component leaves propagate to GO complex terms.
- [class] Autophagy-Lysosome Pathway|Autophagophore initiation and elongation
  status=context_only scope=too_broad_to_propagate GO=[GO:0016236 macroautophagy]
  rationale: This class is a real macroautophagy context, but its descendants include core factors, component buckets, upstream modulators, localization roles, and residual categories. Projecting generic macroautophagy from this ancestor creates TRAPP-like overpropagation, so candidate GO annotations must come from narrower curated nodes.
- [branch] Autophagy-Lysosome Pathway
  status=no_mapping scope= GO=[]
  rationale: Reviewed as the top-level PN branch. It is a project taxonomy umbrella rather than a direct GO assertion; all propagation must come from manually curated child nodes.

PN row 2: Autophagy-Lysosome Pathway | Autophagy substrate selection | Selective autophagy receptor | Mitophagy

UniProt: O60238
In branches: ALP
Notes: Mitochondrial membrane protein. Inhibits RHEB, also releases BECN1 from complexes with Bcl2 or BclXL. Also is a receptor for mitophagy by binding to LC3 through an LIR domain and enhances autophagy in response to hypoxia.
PN references (titles):
- Atypical BH3-domains of BNIP3 and BNIP3L lead to autophagy in hypoxia (tandfonline.com)
- A brief overview of BNIP3L/NIX receptor‐mediated mitophagy - Marinković - 2021 - FEBS Open Bio - Wiley Online Library
- The dynamics of mitochondrial autophagy at the initiation stage | Biochemical Society Transactions | Portland Press
PN-node mapping records (path + ancestors):
- [type] Autophagy-Lysosome Pathway|Autophagy substrate selection|Selective autophagy receptor|Mitophagy
  status=mapped scope=ok_for_propagation_to_go GO=[GO:0000423 mitophagy]
  rationale: This PN path denotes selective-autophagy receptors for mitochondrial cargo. The source category is a mechanistic sub-role within mitophagy, so propagation rather than exact equivalence is the correct scope.
- [group] Autophagy-Lysosome Pathway|Autophagy substrate selection|Selective autophagy receptor
  status=no_mapping scope= GO=[]
  rationale: Reviewed as a broad PN taxonomy container. The descendants mix components, regulators, context labels, and mechanistic leaves, so propagation should come only from narrower curated nodes.
- [class] Autophagy-Lysosome Pathway|Autophagy substrate selection
  status=no_mapping scope= GO=[]
  rationale: Reviewed as a broad substrate-selection container. GO has useful targets for specific receptor, cargo-adaptor, and selective-autophagy leaves, but this class mixes marking, recognition, receptor regulation, and unknown roles and should not propagate as one term.
- [branch] Autophagy-Lysosome Pathway
  status=no_mapping scope= GO=[]
  rationale: Reviewed as the top-level PN branch. It is a project taxonomy umbrella rather than a direct GO assertion; all propagation must come from manually curated child nodes.

Projected GO annotations (1)

GO:0000423 mitophagy | scope=ok_for_propagation_to_go | goa_status=supported_by_goa_regulation | from=Autophagy-Lysosome Pathway|Autophagy substrate selection|Selective autophagy receptor|Mitophagy

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: O60238
gene_symbol: BNIP3L
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: 'BNIP3L (NIX) is a tail-anchored, atypical BH3-containing member of the BNIP3/NIP3 family that is inserted into the mitochondrial outer membrane via its C-terminal transmembrane helix, with its N-terminal disordered region facing the cytosol. Its principal, conserved function is as a selective autophagy (mitophagy) receptor: an LC3-interacting region in the cytosolic domain binds Atg8-family proteins (LC3 and GABARAP/GABARAPL1/GABARAPL2), tethering mitochondria to the forming autophagosome and driving their programmed autophagic clearance. This is most prominent during terminal erythroid/reticulocyte maturation and other developmentally programmed or stress-induced episodes of mitochondrial turnover. NIX also participates in non-canonical mitochondrial quality control through ROS-dependent interaction with SPATA18/MIEAP, and under hypoxia it is induced by HIF and promotes pro-survival macroautophagy via its atypical BH3 domain. Although first described as a pro-apoptotic BCL-2-family protein, its effects on cell death are context-dependent and direction-dependent (it can both promote and inhibit cell death) and act largely through mitochondrial membrane permeability/necrosis rather than classical cytochrome-c/caspase apoptosis. Beyond mitochondria, NIX can independently localize to peroxisomes and act as a selective autophagy receptor for their clearance (pexophagy), broadening its cargo selectivity. NIX abundance is held in check by constitutive ubiquitin-mediated turnover: an SCF(FBXL4) ubiquitin ligase complex at the mitochondrial outer membrane, with the phosphatase PPTC7 as a cofactor, degrades NIX (and BNIP3) to restrain basal mitophagy, while hypoxia/HIF signaling induces NIX transcription. NIX is also exploited by several viruses, which hijack NIX-mediated mitophagy to degrade mitochondrial antiviral signaling components.'
alternative_products:
- name: '1'
  id: O60238-1
- name: '2'
  id: O60238-2
  sequence_note: VSP_056248
existing_annotations:
- term:
    id: GO:0043065
    label: positive regulation of apoptotic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: NIX/BNIP3L was first characterized as a pro-apoptotic BCL-2/NIP3-family protein and can promote cell death in some contexts, but this is direction-dependent and atypical (necrosis/membrane permeability rather than classical caspase apoptosis).
    action: KEEP_AS_NON_CORE
    reason: The pro-apoptotic role is genuine but secondary and context-dependent relative to the conserved mitophagy-receptor function; the same gene also has negative-regulation-of-apoptosis annotations, underscoring that cell-death regulation is contextual.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: Overexpression of BNIP3alpha in transfected cells results in apoptosis and suppresses the antiapoptosis activity of E1B-19K and BCL-xL.
      reference_section_type: ABSTRACT
    - reference_id: PMID:21264228
      supporting_text: in contrast to other mitochondrial Bcl-2 family proteins, NIX and BNIP3 are not involved in the release of cytochrome c and the resulting caspase-dependent apoptosis, but rather related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
      reference_section_type: INTRODUCTION
- term:
    id: GO:0043653
    label: mitochondrial fragmentation involved in apoptotic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Mitochondrial fragmentation in an apoptotic context is a secondary, contextual aspect of NIX biology rather than its core mitophagy-receptor function.
    action: KEEP_AS_NON_CORE
    reason: NIX can promote mitochondrial membrane permeabilization/necrosis-related death, but the conserved core function is selective autophagic clearance of mitochondria, not apoptotic fragmentation.
    supported_by:
    - reference_id: PMID:21264228
      supporting_text: in contrast to other mitochondrial Bcl-2 family proteins, NIX and BNIP3 are not involved in the release of cytochrome c and the resulting caspase-dependent apoptosis, but rather related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
      reference_section_type: INTRODUCTION
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: ER localization is reported for NIX (it was detected in nuclear envelope, ER and mitochondria, and linked to ER Ca2+ handling), but it is a secondary site relative to the mitochondrial outer membrane where the mitophagy-receptor function operates.
    action: KEEP_AS_NON_CORE
    reason: ER localization is documented but is not the primary functional compartment; the is_active_in qualifier overstates ER as a site of NIX activity.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
    - reference_id: PMID:21264228
      supporting_text: NIX was also shown to localize to endoplasmic reticulum (ER) and increase the store of Ca++, leading to Ca++ influx into mitochondria and cell death
      reference_section_type: INTRODUCTION
- term:
    id: GO:0005741
    label: mitochondrial outer membrane
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: The mitochondrial outer membrane is the core functional location of NIX, where its C-terminal transmembrane anchor inserts and its cytosolic LIR engages the autophagy machinery.
    action: ACCEPT
    reason: This is the principal functional compartment for the mitophagy-receptor activity and is strongly supported by multiple independent studies.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
      reference_section_type: ABSTRACT
    - reference_id: PMID:21264228
      supporting_text: A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: A nuclear/nuclear-envelope localization derives from the original B5 study; it is weakly supported and is not the functional compartment for the mitophagy-receptor role.
    action: MARK_AS_OVER_ANNOTATED
    reason: 'is_active_in nucleus is not supported by a defined nuclear function; the only relevant primary data describe nuclear envelope localization, likely reflecting tail-anchored membrane behavior, not nucleoplasmic activity.'
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005635
    label: nuclear envelope
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Nuclear envelope localization is reported in the original B5 study (with associated lamin binding), but it is a secondary, weakly characterized site rather than the functional mitophagy compartment.
    action: KEEP_AS_NON_CORE
    reason: Nuclear envelope localization is documented experimentally but is not where the conserved mitophagy-receptor function acts; retained as non-core.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005635
    label: nuclear envelope
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Automated subcellular-location transfer of nuclear envelope localization, consistent with the experimental B5 data.
    action: KEEP_AS_NON_CORE
    reason: Consistent with documented nuclear envelope localization but secondary to the mitochondrial outer membrane function.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005740
    label: mitochondrial envelope
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: located_in
  review:
    summary: Mitochondrial envelope is a less specific parent of the mitochondrial outer membrane, where NIX is actually anchored.
    action: MODIFY
    reason: The more precise and well-supported localization is the mitochondrial outer membrane; replace the broader envelope term.
    proposed_replacement_terms:
    - id: GO:0005741
      label: mitochondrial outer membrane
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005741
    label: mitochondrial outer membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Automated location transfer of the well-supported mitochondrial outer membrane localization.
    action: ACCEPT
    reason: Strongly supported as the core functional compartment.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Automated transfer of ER localization, consistent with experimental detection of NIX in the ER.
    action: KEEP_AS_NON_CORE
    reason: ER localization is documented but is a secondary site relative to the mitochondrial outer membrane.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: NIX is a single-pass tail-anchored membrane protein, so generic membrane localization is correct but uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: The generic membrane term is subsumed by the specific and well-supported mitochondrial outer membrane localization.
    supported_by:
    - reference_id: file:human/BNIP3L/BNIP3L-uniprot.txt
      supporting_text: Single-pass
      reference_section_type: DATABASE_ENTRY
- term:
    id: GO:0043065
    label: positive regulation of apoptotic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: involved_in
  review:
    summary: Automated transfer of the pro-apoptotic process annotation; genuine but context-dependent and not the core function.
    action: KEEP_AS_NON_CORE
    reason: Cell-death promotion by NIX is contextual and direction-dependent; secondary to mitophagy.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: Overexpression of BNIP3alpha in transfected cells results in apoptosis and suppresses the antiapoptosis activity of E1B-19K and BCL-xL.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:10381623
  qualifier: enables
  review:
    summary: Generic protein-binding annotation; the underlying B5 data describe specific self-association and BNIP3 heterodimerization, captured better by homodimerization activity.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding is uninformative; the specific interactions are represented by the identical protein binding / homodimerization annotations from this same study.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16189514
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a proteome-scale interaction map does not identify an interpretable NIX function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19060904
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a binary interactome dataset does not specify a meaningful function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21516116
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from an interactome-mapping method is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22645275
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from an ATP13A2/alpha-synuclein interactome study; uninformative for core NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding does not specify a NIX function; the interaction is not tied to core mitophagy biology.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24316735
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from a TR3/NR4A1 autophagic-cell-death study; uninformative as bare protein binding.
    action: MARK_AS_OVER_ANNOTATED
    reason: The term protein binding is too general; the NR4A1 interaction is not informative as core NIX function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24981860
  qualifier: enables
  review:
    summary: High-throughput chromatin-related interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a large-scale interaction study does not specify a NIX function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25416956
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a proteome-scale interactome map is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25910212
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a disease-interactome perturbation study is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:27107012
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a pooled interaction screen does not specify a NIX function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:28514442
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a large-scale interactome study is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:31515488
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a variant-interaction study is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a reference binary interactome map is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: High-throughput interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a cell-specific interactome remodeling study is not functionally specific.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:34845370
  qualifier: enables
  review:
    summary: This protein-binding annotation reflects the specific, functionally important interaction of NIX with SARS-CoV-2 ORF10 and LC3B during virus-hijacked mitophagy; as bare protein binding it is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: The underlying interaction is meaningful (ORF10/LC3B binding driving NIX-mediated mitophagy), but the generic protein binding term does not capture it; the antiviral mitophagy biology is curated under defense response to virus.
    supported_by:
    - reference_id: PMID:34845370
      supporting_text: ORF10 was translocated to mitochondria by interacting with the mitophagy receptor Nip3-like protein X (NIX) and induced mitophagy through its interaction with both NIX and LC3B
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:39526800
  qualifier: enables
  review:
    summary: High-throughput Legionella effector two-hybrid interactome protein-binding annotation; uninformative for NIX function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic protein binding from a pathogen-effector interactome screen is not functionally specific for NIX.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:9973195
  qualifier: enables
  review:
    summary: Generic protein-binding annotation; the underlying data describe specific interactions with E1B-19K, BCL-2 and BCL-xL, not informative as bare binding.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding is uninformative; the specific anti-apoptotic-protein interactions are better represented elsewhere.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: BNIP3alpha interacts with viral antiapoptosis protein E1B-19K and cellular antiapoptosis proteins BCL-2 and BCL-xL.
      reference_section_type: ABSTRACT
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:10381623
  qualifier: enables
  review:
    summary: NIX/B5 self-associates, and the original study directly shows it binds itself; identical protein binding (self-association) is supported.
    action: ACCEPT
    reason: Self-association is directly demonstrated and is a genuine, informative molecular property of NIX.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:16189514
  qualifier: enables
  review:
    summary: NIX self-association is recorded as identical protein binding in a high-throughput interactome (IntAct O60238-O60238); consistent with directly demonstrated self-association.
    action: ACCEPT
    reason: NIX self-association is independently supported by direct biochemistry; the high-throughput identical-protein-binding hit is consistent and informative.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:21516116
  qualifier: enables
  review:
    summary: NIX self-association recorded as identical protein binding from interactome mapping; consistent with demonstrated self-association.
    action: ACCEPT
    reason: Consistent with directly demonstrated NIX self-association and informative as a homodimerization property.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:25416956
  qualifier: enables
  review:
    summary: NIX self-association recorded as identical protein binding from a proteome-scale interactome; consistent with demonstrated self-association.
    action: ACCEPT
    reason: Consistent with directly demonstrated NIX self-association.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:27107012
  qualifier: enables
  review:
    summary: NIX self-association recorded as identical protein binding from a pooled interaction screen; consistent with demonstrated self-association.
    action: ACCEPT
    reason: Consistent with directly demonstrated NIX self-association.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: General mitochondrial localization; correct but less specific than the mitochondrial outer membrane localization.
    action: KEEP_AS_NON_CORE
    reason: Accurate but subsumed by the more precise mitochondrial outer membrane annotation.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: Like BNIP3, BNIP3alpha seems to be predominantly localized in mitochondria.
      reference_section_type: ABSTRACT
- term:
    id: GO:0010917
    label: negative regulation of mitochondrial membrane potential
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: NIX/BNIP3 can affect mitochondrial membrane potential/permeability (linked to necrosis and to depolarization-triggered mitophagy), a contextual mitochondrial effect.
    action: KEEP_AS_NON_CORE
    reason: Effects on membrane potential are documented but are a downstream/contextual aspect rather than the core mitophagy-receptor activity.
    supported_by:
    - reference_id: PMID:21264228
      supporting_text: related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
      reference_section_type: INTRODUCTION
- term:
    id: GO:0035794
    label: positive regulation of mitochondrial membrane permeability
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: NIX/BNIP3 are linked to opening of the mitochondrial permeability transition pore and necrosis-related membrane permeabilization, a contextual function.
    action: KEEP_AS_NON_CORE
    reason: Supported as a contextual mitochondrial membrane effect; secondary to mitophagy-receptor activity.
    supported_by:
    - reference_id: PMID:21264228
      supporting_text: related to necrosis through the regulation of mitochondrial permeability transition pore (MPTP)
      reference_section_type: INTRODUCTION
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: Automated identical-protein-binding annotation, consistent with directly demonstrated NIX self-association.
    action: ACCEPT
    reason: Consistent with documented NIX self-association.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:1901524
    label: regulation of mitophagy
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Regulation of mitophagy is a core process for NIX, which acts as a mitochondrial receptor connecting mitochondria to the autophagy machinery via LC3/GABARAP.
    action: ACCEPT
    reason: Mitophagy is the defining conserved function of NIX and is strongly supported.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
      reference_section_type: ABSTRACT
- term:
    id: GO:1903747
    label: regulation of protein localization to mitochondrion
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: NIX recruits autophagy machinery (LC3/GABARAP) to mitochondria; this can be viewed as regulating protein localization to the mitochondrion, but it is better represented by mitophagy receptor activity.
    action: KEEP_AS_NON_CORE
    reason: The annotation captures a mechanistic aspect (recruitment of Atg8-family proteins to mitochondria) of the core mitophagy function but as a broad regulatory term is less precise; retained as non-core.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: Immunofluorescence-based mitochondrial localization, consistent with the predominant mitochondrial localization of NIX.
    action: KEEP_AS_NON_CORE
    reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: Like BNIP3, BNIP3alpha seems to be predominantly localized in mitochondria.
      reference_section_type: ABSTRACT
- term:
    id: GO:0016607
    label: nuclear speck
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: A nuclear speck localization (HPA immunofluorescence) is weakly supported and inconsistent with the established tail-anchored mitochondrial outer membrane biology of NIX.
    action: MARK_AS_OVER_ANNOTATED
    reason: No defined nuclear-speck function exists for NIX; this single-source localization likely reflects antibody/overexpression artifact and is not the functional compartment.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: HTP
  original_reference_id: PMID:34800366
  qualifier: located_in
  review:
    summary: High-throughput mitochondrial proteome localization, consistent with NIX being a mitochondrial protein.
    action: KEEP_AS_NON_CORE
    reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization.
    supported_by:
    - reference_id: PMID:34800366
      supporting_text: mitochondrial proteome
      reference_section_type: TITLE
- term:
    id: GO:0043069
    label: negative regulation of programmed cell death
  evidence_type: IGI
  original_reference_id: PMID:19273585
  qualifier: acts_upstream_of_or_within
  review:
    summary: Under hypoxia, HIF-induced BNIP3/BNIP3L promote pro-survival autophagy and their ablation triggers cell death, supporting a negative regulation of programmed cell death role in this context.
    action: KEEP_AS_NON_CORE
    reason: Supported by genetic evidence but contextual (hypoxia/survival); secondary to the core mitophagy-receptor function.
    supported_by:
    - reference_id: PMID:19273585
      supporting_text: the ablation of BNIP3 and/or BNIP3L triggers cell death
      reference_section_type: ABSTRACT
    - reference_id: PMID:19273585
      supporting_text: Hypoxia-induced autophagy via BNIP3 and BNIP3L is clearly a survival mechanism that promotes tumor progression.
      reference_section_type: ABSTRACT
- term:
    id: GO:0016239
    label: positive regulation of macroautophagy
  evidence_type: IGI
  original_reference_id: PMID:19273585
  qualifier: acts_upstream_of_or_within
  review:
    summary: BNIP3/BNIP3L are required for hypoxia-induced macroautophagy and their atypical BH3 domains can initiate autophagy by disrupting the Bcl-2-Beclin1 complex.
    action: ACCEPT
    reason: Positive regulation of macroautophagy is well supported by combined silencing/ectopic expression and BH3-peptide experiments, and is closely tied to the autophagy-receptor biology of NIX.
    supported_by:
    - reference_id: PMID:19273585
      supporting_text: the combined silencing of these two HIF targets suppresses hypoxia-mediated autophagy
      reference_section_type: ABSTRACT
    - reference_id: PMID:19273585
      supporting_text: the ectopic expression of both BNIP3 and BNIP3L in normoxia activates autophagy
      reference_section_type: ABSTRACT
- term:
    id: GO:0071456
    label: cellular response to hypoxia
  evidence_type: IGI
  original_reference_id: PMID:19273585
  qualifier: acts_upstream_of_or_within
  review:
    summary: BNIP3L is a HIF target that mediates hypoxia-induced autophagy, supporting a role in the cellular response to hypoxia.
    action: KEEP_AS_NON_CORE
    reason: Supported as part of the hypoxia/HIF-autophagy axis but is a contextual upstream process rather than the core molecular function.
    supported_by:
    - reference_id: PMID:19273585
      supporting_text: the combined silencing of these two HIF targets suppresses hypoxia-mediated autophagy
      reference_section_type: ABSTRACT
- term:
    id: GO:0005741
    label: mitochondrial outer membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6798004
  qualifier: located_in
  review:
    summary: Reactome-curated mitochondrial outer membrane localization (TP53 stimulates BNIP3L expression pathway).
    action: ACCEPT
    reason: Consistent with the well-supported core localization.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005741
    label: mitochondrial outer membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6801195
  qualifier: located_in
  review:
    summary: Reactome-curated mitochondrial outer membrane localization (STEAP3 binds BNIP3L pathway).
    action: ACCEPT
    reason: Consistent with the well-supported core localization.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:20200478
  qualifier: enables
  review:
    summary: This protein-binding annotation reflects the functionally central interaction of NIX with the Atg8 homologs LC3/GABARAP, but as bare protein binding it is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: The underlying LC3/GABARAP interaction is the molecular basis of NIX mitophagy-receptor activity; bare protein binding does not capture this and the function is curated under regulation of mitophagy.
    supported_by:
    - reference_id: PMID:20200478
      supporting_text: Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
      reference_section_type: ABSTRACT
- term:
    id: GO:0043065
    label: positive regulation of apoptotic process
  evidence_type: IDA
  original_reference_id: PMID:9973195
  qualifier: involved_in
  review:
    summary: Overexpression of BNIP3alpha induced apoptosis in transfected cells, providing direct (if overexpression-based) evidence for a pro-apoptotic role.
    action: KEEP_AS_NON_CORE
    reason: Direct evidence supports a pro-apoptotic capacity, but it is context-dependent/overexpression-driven and secondary to the conserved mitophagy function.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: Overexpression of BNIP3alpha in transfected cells results in apoptosis and suppresses the antiapoptosis activity of E1B-19K and BCL-xL.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21264221
  qualifier: enables
  review:
    summary: Generic protein-binding annotation associated with the Mieap/MALM mitochondrial quality-control studies; uninformative as bare binding.
    action: MARK_AS_OVER_ANNOTATED
    reason: Bare protein binding is uninformative; the relevant NIX-SPATA18/Mieap interaction is curated via the mitochondrial protein catabolic process annotation.
- term:
    id: GO:0005741
    label: mitochondrial outer membrane
  evidence_type: IMP
  original_reference_id: PMID:21264228
  qualifier: located_in
  review:
    summary: NIX localizes to and acts at the mitochondrial outer membrane, where it interacts with Mieap via its BH3 domain; mutational/localization analysis supports this compartment.
    action: ACCEPT
    reason: Directly supported core localization.
    supported_by:
    - reference_id: PMID:21264228
      supporting_text: A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap.
      reference_section_type: ABSTRACT
- term:
    id: GO:0035694
    label: mitochondrial protein catabolic process
  evidence_type: IMP
  original_reference_id: PMID:21264228
  qualifier: involved_in
  review:
    summary: NIX is an essential mediator of MALM (Mieap-induced accumulation of lysosome-like organelles within mitochondria), a non-canonical process that degrades oxidized mitochondrial proteins; NIX deficiency impairs MALM.
    action: ACCEPT
    reason: Loss-of-function (NIX knockdown) directly impairs MALM, supporting NIX involvement in mitochondrial protein catabolism within the mitochondrial quality-control context.
    supported_by:
    - reference_id: PMID:21264228
      supporting_text: Deficiency of NIX also completely impaired MALM.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005521
    label: lamin binding
  evidence_type: IPI
  original_reference_id: PMID:10381623
  qualifier: enables
  review:
    summary: Lamin binding derives from the original B5/nuclear-envelope study; it is a specific but secondary interaction not central to the mitophagy-receptor function.
    action: KEEP_AS_NON_CORE
    reason: Retained as a specific (non-generic) binding annotation, but it is contextual to the nuclear-envelope localization and not the core function.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005521
    label: lamin binding
  evidence_type: IDA
  original_reference_id: PMID:10381623
  qualifier: enables
  review:
    summary: Direct-assay lamin binding from the original B5 study; specific but secondary.
    action: KEEP_AS_NON_CORE
    reason: Specific binding annotation tied to nuclear-envelope localization; not the core function.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005635
    label: nuclear envelope
  evidence_type: IDA
  original_reference_id: PMID:10381623
  qualifier: located_in
  review:
    summary: Direct localization of B5/NIX to the nuclear envelope in the original study; secondary site.
    action: KEEP_AS_NON_CORE
    reason: Documented but secondary localization relative to the mitochondrial outer membrane.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: PMID:10381623
  qualifier: located_in
  review:
    summary: Direct mitochondrial localization in the original B5 study.
    action: KEEP_AS_NON_CORE
    reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IDA
  original_reference_id: PMID:10381623
  qualifier: located_in
  review:
    summary: Direct ER localization in the original B5 study; secondary site.
    action: KEEP_AS_NON_CORE
    reason: Documented but secondary localization relative to the mitochondrial outer membrane.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: localizes in nuclear envelope, endoplasmic reticulum and mitochondria
      reference_section_type: ABSTRACT
- term:
    id: GO:0016020
    label: membrane
  evidence_type: TAS
  original_reference_id: PMID:10381623
  qualifier: located_in
  review:
    summary: NIX/B5 contains a C-terminal transmembrane region; generic membrane localization is correct but uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: Subsumed by the specific mitochondrial outer membrane localization.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: contains the putative BH3 and transmembrane regions
      reference_section_type: ABSTRACT
- term:
    id: GO:0042803
    label: protein homodimerization activity
  evidence_type: IDA
  original_reference_id: PMID:10381623
  qualifier: enables
  review:
    summary: NIX/B5 self-associates (binds itself), supporting protein homodimerization activity as a genuine molecular property.
    action: ACCEPT
    reason: Directly demonstrated self-association; informative homodimerization activity.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 binds strongly to Nip3 and itself
      reference_section_type: ABSTRACT
- term:
    id: GO:0043066
    label: negative regulation of apoptotic process
  evidence_type: IDA
  original_reference_id: PMID:10381623
  qualifier: involved_in
  review:
    summary: In the original B5 study, NIX did not itself induce apoptosis but inhibited Nip3(BNIP3)-induced apoptosis, supporting an anti-apoptotic capacity in this context.
    action: KEEP_AS_NON_CORE
    reason: This anti-apoptotic effect is genuine but direction- and context-dependent (the same protein can also promote death); secondary to mitophagy.
    supported_by:
    - reference_id: PMID:10381623
      supporting_text: B5 does not induce apoptosis, but inhibits apoptosis induced by Nip3
      reference_section_type: ABSTRACT
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: PMID:9973195
  qualifier: located_in
  review:
    summary: Direct mitochondrial localization of BNIP3alpha/NIX.
    action: KEEP_AS_NON_CORE
    reason: Accurate but subsumed by the more precise mitochondrial outer membrane localization.
    supported_by:
    - reference_id: PMID:9973195
      supporting_text: Like BNIP3, BNIP3alpha seems to be predominantly localized in mitochondria.
      reference_section_type: ABSTRACT
- term:
    id: GO:0051607
    label: defense response to virus
  evidence_type: IDA
  original_reference_id: PMID:9973195
  qualifier: involved_in
  review:
    summary: The cited 1999 BNIP3alpha paper is about apoptosis/anti-apoptotic-protein interactions and does not provide direct evidence for defense response to virus; the genuine antiviral connection (NIX-mediated mitophagy degrading MAVS) is established by later work, but viruses hijack this for immune evasion rather than NIX acting in host antiviral defense.
    action: REMOVE
    reason: The original reference (PMID:9973195) was reviewed and is about apoptosis/anti-apoptotic-protein interactions; it provides no evidence for a defense-response-to-virus role (this is therefore a removal on reviewed evidence, not an UNDECIDED due to inaccessible literature). Later literature (PMID:34845370) shows NIX-mediated mitophagy is hijacked by SARS-CoV-2 ORF10 to degrade MAVS and suppress innate immunity, the opposite of host antiviral defense; KSHV vIRF-1 similarly co-opts NIX. The annotation is unlikely to be correct based on the combined evidence.
    supported_by:
    - reference_id: PMID:34845370
      supporting_text: ORF10 was translocated to mitochondria by interacting with the mitophagy receptor Nip3-like protein X (NIX) and induced mitophagy through its interaction with both NIX and LC3B
      reference_section_type: ABSTRACT
    - reference_id: PMID:34845370
      supporting_text: NIX-mediated mitophagy is responsible for the elimination of spontaneously aggregated MAVS
      reference_section_type: INTRODUCTION
    additional_reference_ids:
    - PMID:34845370
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:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to
    orthologs using Ensembl Compara
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10381623
  title: A novel adenovirus E1B19K-binding protein B5 inhibits apoptosis induced by
    Nip3 by forming a heterodimer through the C-terminal hydrophobic region.
  findings: []
- id: PMID:16189514
  title: Towards a proteome-scale map of the human protein-protein interaction network.
  findings: []
- id: PMID:19060904
  title: An empirical framework for binary interactome mapping.
  findings: []
- id: PMID:19273585
  title: Hypoxia-induced autophagy is mediated through hypoxia-inducible factor induction
    of BNIP3 and BNIP3L via their BH3 domains.
  findings: []
- id: PMID:20200478
  title: Nix, a receptor protein for mitophagy in mammals.
  findings: []
- id: PMID:21264221
  title: Possible existence of lysosome-like organella within mitochondria and its
    role in mitochondrial quality control.
  findings: []
- id: PMID:21264228
  title: Mieap, a p53-inducible protein, controls mitochondrial quality by repairing
    or eliminating unhealthy mitochondria.
  findings: []
- id: PMID:21516116
  title: Next-generation sequencing to generate interactome datasets.
  findings: []
- id: PMID:22645275
  title: Identification of novel ATP13A2 interactors and their role in α-synuclein
    misfolding and toxicity.
  findings: []
- id: PMID:24316735
  title: Orphan nuclear receptor TR3 acts in autophagic cell death via mitochondrial
    signaling pathway.
  findings: []
- id: PMID:24981860
  title: Human-chromatin-related protein interactions identify a demethylase complex
    required for chromosome segregation.
  findings: []
- id: PMID:25416956
  title: A proteome-scale map of the human interactome network.
  findings: []
- id: PMID:25910212
  title: Widespread macromolecular interaction perturbations in human genetic disorders.
  findings: []
- id: PMID:27107012
  title: Pooled-matrix protein interaction screens using Barcode Fusion Genetics.
  findings: []
- id: PMID:28514442
  title: Architecture of the human interactome defines protein communities and disease
    networks.
  findings: []
- id: PMID:31515488
  title: Extensive disruption of protein interactions by genetic variants across the
    allele frequency spectrum in human populations.
  findings: []
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human
    interactome.
  findings: []
- id: PMID:34800366
  title: Quantitative high-confidence human mitochondrial proteome and its dynamics
    in cellular context.
  findings: []
- id: PMID:36215693
  title: BNIP3L/NIX regulates both mitophagy and pexophagy.
  full_text_unavailable: true
  findings:
  - statement: NIX, anchored in the mitochondrial outer membrane, also independently localizes
      to peroxisomes and drives their selective autophagic clearance (pexophagy), and Nix-null
      mouse tissue has increased peroxisomal content, showing that NIX acts as a selective
      autophagy receptor for more than one organelle.
- id: PMID:37102372
  title: FBXL4 ubiquitin ligase deficiency promotes mitophagy by elevating NIX levels.
  full_text_unavailable: true
  findings:
  - statement: A CRISPR screen of human E3 ubiquitin ligases identified VHL and FBXL4 as the
      strongest negative regulators of basal mitophagy, both converging on the mitophagy
      receptors BNIP3 and BNIP3L/NIX; FBXL4 destabilizes NIX/BNIP3 directly while VHL acts by
      suppressing HIF-1alpha-mediated transcription, and depletion of NIX is sufficient to
      restore mitophagy levels.
- id: PMID:37161784
  title: FBXL4 suppresses mitophagy by restricting the accumulation of NIX and BNIP3 mitophagy
    receptors.
  full_text_unavailable: true
  findings:
  - statement: The SCF(FBXL4) ubiquitin ligase complex localizes to the mitochondrial outer
      membrane in unstressed cells and constitutively ubiquitylates and degrades the mitophagy
      receptors NIX and BNIP3 to suppress basal mitophagy; pathogenic FBXL4 variants causing
      mtDNA depletion syndrome (MTDPS13) fail to mediate this turnover, linking dysregulated NIX
      accumulation to excessive basal mitophagy.
- id: PMID:37621214
  title: Nix interacts with WIPI2 to induce mitophagy.
  full_text_unavailable: true
  findings:
  - statement: In addition to its LIR motif that binds ATG8 proteins, NIX contains a minimal
      essential region (MER) that binds and recruits the autophagy effector WIPI2 to
      mitochondria; both the MER and the LIR are required for robust mitophagy, with the LIR
      reorganizing WIPI2 into puncta even in the absence of ATG8 proteins.
- id: PMID:38991726
  title: Dual-localized PPTC7 limits mitophagy through proximal and dynamic interactions with
    BNIP3 and NIX.
  full_text_unavailable: true
  findings:
  - statement: A pool of the mitochondrial phosphatase PPTC7 localizes to the outer mitochondrial
      membrane, dynamically associates with BNIP3 and NIX, and promotes their proteasomal
      turnover to limit basal mitophagy, acting post-transcriptionally and independently of
      HIF-1alpha stabilization.
- id: PMID:38992176
  title: 'PPTC7 antagonizes mitophagy by promoting BNIP3 and NIX degradation via SCF(FBXL4).'
  full_text_unavailable: true
  findings:
  - statement: PPTC7 is an essential cofactor for SCF(FBXL4)-mediated degradation of the BNIP3
      and NIX mitophagy receptors, acting as an outer-mitochondrial-membrane adaptor that links
      BNIP3/NIX to FBXL4 to suppress both steady-state and induced mitophagy, with the turnover
      function independent of PPTC7 phosphatase activity.
- id: PMID:34845370
  title: SARS-CoV-2 ORF10 suppresses the antiviral innate immune response by degrading
    MAVS through mitophagy.
  findings: []
- id: PMID:39526800
  title: A comprehensive two-hybrid analysis to explore the Legionella pneumophila
    effector-effector interactome.
  findings: []
- id: PMID:9973195
  title: 'BNIP3alpha: a human homolog of mitochondrial proapoptotic protein BNIP3.'
  findings: []
- id: Reactome:R-HSA-6798004
  title: TP53 stimulates BNIP3L expression
  findings: []
- id: Reactome:R-HSA-6801195
  title: STEAP3 binds BNIP3L
  findings: []
- id: file:human/BNIP3L/BNIP3L-uniprot.txt
  title: BNIP3L (NIX) UniProtKB record O60238
  findings: []
- id: file:human/BNIP3L/BNIP3L-notes.md
  title: Manual BNIP3L curation notes
  findings: []
core_functions:
- description: BNIP3L/NIX functions as a mitophagy receptor at the mitochondrial outer membrane. Anchored by its C-terminal transmembrane helix with an N-terminal cytosolic region containing an LC3-interacting region, it directly binds Atg8-family proteins (LC3 and GABARAP) to tether mitochondria to the forming autophagosome, driving selective autophagic clearance of mitochondria. This is essential for mitochondrial elimination during terminal erythroid/reticulocyte maturation and contributes to developmentally programmed and stress-induced mitochondrial turnover.
  directly_involved_in:
  - id: GO:1901524
    label: regulation of mitophagy
  - id: GO:0016239
    label: positive regulation of macroautophagy
  locations:
  - id: GO:0005741
    label: mitochondrial outer membrane
  supported_by:
  - reference_id: PMID:20200478
    supporting_text: Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
    reference_section_type: ABSTRACT
  - reference_id: PMID:20200478
    supporting_text: Nix is a mitochondrial outer membrane protein that is required for mitochondrial clearance during erythrocyte maturation.
    reference_section_type: ABSTRACT
- description: Under hypoxia, NIX (a HIF target) promotes pro-survival macroautophagy. Its atypical BH3 domain can disrupt the Bcl-2-Beclin1 complex to initiate autophagy without inducing cell death, and combined loss of BNIP3 and BNIP3L suppresses hypoxia-induced autophagy.
  directly_involved_in:
  - id: GO:0016239
    label: positive regulation of macroautophagy
  - id: GO:0071456
    label: cellular response to hypoxia
  locations:
  - id: GO:0005741
    label: mitochondrial outer membrane
  supported_by:
  - reference_id: PMID:19273585
    supporting_text: the atypical BH3 domains of hypoxia-induced BNIP3/BNIP3L have
    reference_section_type: ABSTRACT
  - reference_id: PMID:19273585
    supporting_text: the ectopic expression of both BNIP3 and BNIP3L in normoxia activates autophagy
    reference_section_type: ABSTRACT
- description: NIX participates in non-canonical mitochondrial quality control via ROS-dependent interaction with SPATA18/MIEAP, acting as an essential mediator of MALM that degrades oxidized mitochondrial proteins; NIX deficiency abolishes MALM.
  directly_involved_in:
  - id: GO:0035694
    label: mitochondrial protein catabolic process
  locations:
  - id: GO:0005741
    label: mitochondrial outer membrane
  supported_by:
  - reference_id: PMID:21264228
    supporting_text: A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap.
    reference_section_type: ABSTRACT
  - reference_id: PMID:21264228
    supporting_text: Deficiency of NIX also completely impaired MALM.
    reference_section_type: ABSTRACT
proposed_new_terms:
- proposed_name: mitophagy receptor activity
  proposed_definition: A protein-tethering activity in which a mitochondrial outer membrane protein bridges the mitochondrion to an Atg8-family protein (LC3/GABARAP) via an LC3-interacting region (LIR), thereby targeting the mitochondrion for selective autophagic degradation (mitophagy).
  justification: NIX/BNIP3L's defining molecular activity is acting as a selective autophagy (mitophagy) receptor that bridges the mitochondrial outer membrane to Atg8-family proteins (LC3/GABARAP) via its LIR motif. No existing molecular-function term in the seeded annotation set captures this cargo-receptor activity; the closest existing term used is protein homodimerization activity, which is incomplete.
  supported_by:
  - reference_id: PMID:20200478
    supporting_text: Nix is a mitochondrial receptor that can directly connect to one of the autophagic machinery components, the Atg8 homologs LC3 and GABARAP.
    reference_section_type: ABSTRACT
suggested_questions:
- question: Does human NIX have a genuine host-protective antiviral function, or is NIX-mediated mitophagy primarily a target that diverse viruses hijack (e.g., SARS-CoV-2 ORF10, KSHV vIRF-1) to degrade MAVS and evade innate immunity?
  experts:
  - He H
  - Choi YB
- question: How is the balance between NIX-driven pro-survival mitophagy and NIX-associated cell death (necrosis/membrane permeabilization) controlled in a given cell type and stress context?
  experts:
  - Mazure NM
  - Dorn GW
- question: To what extent is NIX-mediated pexophagy a distinct cargo-selection program versus a by-product of shared upstream (iron-chelation/HIF) signaling, and is the peroxisomal pool of NIX targeted or regulated differently from the mitochondrial pool?
  experts:
  - Ganley IG
  - Boya P
- question: Is the FBXL4/PPTC7-mediated constitutive turnover of NIX a general rheostat for basal mitophagy across tissues, and does failure of this turnover (e.g., FBXL4 variants) cause disease specifically through NIX rather than BNIP3 accumulation?
  experts:
  - Pagan JK
  - Niemi NM
suggested_experiments:
- hypothesis: NIX functions as an LIR-dependent mitophagy receptor whose Atg8-family binding is required for programmed mitochondrial clearance.
  description: Compare wild-type NIX with LIR-motif point mutants (abolishing LC3/GABARAP binding) for their ability to rescue mitochondrial clearance during reticulocyte maturation and stress-induced mitophagy in NIX-null cells, using flow cytometry of mitochondrial mass and mito-Keima/mito-QC reporters.
  experiment_type: structure-function rescue and mitophagy flux assay
- hypothesis: NIX-mediated mitophagy is required for MAVS turnover and shapes innate antiviral signaling.
  description: Knock out NIX in cells and measure MAVS levels, type I interferon induction, and viral replication with and without virus-encoded mitophagy inducers (e.g., ORF10), distinguishing host-protective versus virus-exploited roles.
  experiment_type: loss-of-function antiviral signaling assay
- hypothesis: NIX acts as a selective autophagy receptor for peroxisomes (pexophagy) in addition to mitochondria, using a peroxisome-localized pool distinct from its mitochondrial pool.
  description: In NIX-null cells reconstituted with wild-type versus LIR-mutant NIX, quantify pexophagy flux (pexo-QC/pexophagy reporters and peroxisomal marker PMP70 loss) under iron chelation and during cardiomyocyte/erythroid differentiation, and use organelle fractionation plus targeted (peroxisome- vs mitochondria-restricted) NIX constructs to test whether peroxisomal cargo selection is separable from mitochondrial mitophagy.
  experiment_type: structure-function rescue and selective-autophagy flux assay

BNIP3L

Gene Description

Proposed New Ontology Terms

mitophagy receptor activity

Existing Annotations Review

Core Functions

Under hypoxia, NIX (a HIF target) promotes pro-survival macroautophagy. Its atypical BH3 domain can disrupt the Bcl-2-Beclin1 complex to initiate autophagy without inducing cell death, and combined loss of BNIP3 and BNIP3L suppresses hypoxia-induced autophagy.

NIX participates in non-canonical mitochondrial quality control via ROS-dependent interaction with SPATA18/MIEAP, acting as an essential mediator of MALM that degrades oxidized mitochondrial proteins; NIX deficiency abolishes MALM.

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Comprehensive research report: Human BNIP3L (NIX) — functional annotation (UniProt O60238)

1) Gene/protein identity verification (mandatory)

2) Key concepts and definitions (current understanding)

2.1 Receptor-mediated mitophagy

2.2 BNIP3L/NIX protein class and topology

2.3 LIR (LC3-interacting region) and ATG8 proteins

2.4 MER (minimal essential region)

2.5 BH3-only domain (atypical)

3) Molecular function: what BNIP3L/NIX “does”

3.1 Primary function: selective autophagy receptor for mitochondria

3.2 Dual mechanism: LIR + MER/WIPI2 for robust mitophagy (major 2023 advance)

3.3 Additional selective autophagy role: pexophagy (peroxisome autophagy)

4) Subcellular localization: where BNIP3L/NIX acts

5) Pathways and regulation (focus on 2023–2024)

5.1 Transcriptional control by hypoxia signaling (HIF-1α) and VHL

5.2 Post-translational “brakes” restricting basal mitophagy: FBXL4 and PPTC7

5.3 Phosphoregulation and dimerization

6) Physiological roles (precision over pleiotropy)

6.1 Erythroid maturation and programmed mitochondrial clearance

6.2 Basal mitophagy and organelle homeostasis

6.3 Coordinated peroxisome turnover (pexophagy)

7) Recent developments (prioritize 2023–2024)

7.1 2023: MER–WIPI2 mechanism clarifies how NIX initiates mitophagy

7.2 2023: FBXL4 identified as a central suppressor of receptor-mediated mitophagy

7.3 2024: PPTC7 emerges as a mechanistic cofactor regulating BNIP3/NIX turnover

7.4 2024: pexophagy pharmacology via VHL inhibition and HIF-1α activation

8) Current applications and real-world implementations

8.1 Experimental/biotech implementation: assays and models in current use

8.2 Pharmacologic modulation of BNIP3L/NIX pathways (research tools; therapeutic hypotheses)

8.3 Clinical trial landscape

9) Expert opinions / authoritative synthesis (2024 perspective)

10) Statistics and quantitative findings (from recent studies)

11) Figures (visual evidence)

12) Summary of functional annotation (high-confidence)

Embedded artifact

Artifacts

Citations

📚 Additional Documentation

Notes

BNIP3L (NIX) curation notes

Core function synthesis

Hypoxia / autophagy (survival)

Mitochondrial quality control via SPATA18/MIEAP (MALM)

Viral hijacking of NIX-mediated mitophagy (defense response to virus)

Localization

Protein binding annotations

Key existing annotation classification summary

Proposed new term

Falcon deep research findings (2026-06-07)

Pn Notes

BNIP3L PN Consistency Notes

Source Files Checked

Deep Research Files

AIGR Review Snapshot

PN Consistency Summary

Full Consistency Review

PN Dossier Context

PN row 1: Autophagy-Lysosome Pathway | Autophagophore initiation and elongation | Class 3 PI3K complex 1, direct | Modulator of class 3 PI3K complex 1 activity | Modulator of BECN1 availability

PN row 2: Autophagy-Lysosome Pathway | Autophagy substrate selection | Selective autophagy receptor | Mitophagy

Projected GO annotations (1)

Note

📄 View Raw YAML