Affinage

BNIP1

Vesicle transport protein SEC20 · UniProt Q12981

Length
228 aa
Mass
26.1 kDa
Annotated
2026-04-28
42 papers in source corpus 11 papers cited in narrative 11 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

BNIP1 is a BH3-domain-containing SNARE protein anchored in the endoplasmic reticulum membrane that integrates vesicular trafficking with apoptotic and autophagic signaling. As a component of the syntaxin-18 SNARE complex, BNIP1 mediates retrograde Golgi-to-ER transport and ER network formation, and its BH3 domain serves as a regulatory switch: α-SNAP binding to this domain suppresses apoptosis, whereas failure of cis-SNARE complex disassembly exposes the BH3 domain to trigger cell death (PMID:15272311, PMID:23725763). BNIP1 is polyubiquitinated by RNF185 (K63-linked) and RNF186 (K29/K63-linked), linking it to p62-dependent selective autophagy and ER-stress-associated apoptosis, and its loss blocks autophagic flux at the autolysosome stage and impairs lysosomal acidification (PMID:21931693, PMID:23896122, PMID:31344970). Hypomorphic BNIP1 variants in humans cause spondylo-epiphyseal dysplasia associated with defective autophagic clearance (PMID:35266227).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1999 Medium

    Establishing that BNIP1 interacts with anti-apoptotic BCL-2 family members resolved its identity as a BCL-2-binding protein but revealed a potentially BH3-independent binding mode through splice variants.

    Evidence In vitro protein–protein interaction assays with BNIP1 splice variants and BCL2/BCL-XL

    PMID:10217402

    Open questions at the time
    • Single in vitro method without cellular validation
    • Functional significance of BH3-independent binding not demonstrated
    • Splice variant stoichiometry in vivo unknown
  2. 2000 High

    Demonstrating that the BH3 domain is both necessary and sufficient for BNIP1 apoptotic activity — and transferable to BAX — established BNIP1 as a bona fide BH3-only pro-apoptotic protein.

    Evidence Deletion/substitution mutagenesis and domain-swap into BAX with apoptosis readout in transfected cells

    PMID:10822388

    Open questions at the time
    • Physiological trigger for BNIP1-dependent apoptosis unknown
    • Endogenous expression context not addressed
  3. 2004 High

    Identifying BNIP1 as a subunit of the syntaxin-18 SNARE complex unified its dual identity: a SNARE protein whose BH3 domain is normally masked by α-SNAP, switching to a pro-apoptotic state when freed from SNARE complex regulation.

    Evidence Reciprocal co-immunoprecipitation, BH3 mutagenesis, α-SNAP competition, and ER network formation assays

    PMID:15272311

    Open questions at the time
    • Structural basis for α-SNAP versus BCL-2 competition at BH3 domain not resolved
    • Signals that shift BNIP1 from trafficking to apoptotic mode not identified
  4. 2011 Medium

    Discovery that RNF185 K63-polyubiquitinates BNIP1 to recruit p62 and LC3 established a ubiquitin-dependent mechanism linking BNIP1 to selective autophagy.

    Evidence In vivo ubiquitination assays, co-immunoprecipitation, and LC3 accumulation in cultured cells

    PMID:21931693

    Open questions at the time
    • Selectivity of RNF185 for BNIP1 versus other substrates unclear
    • Physiological autophagic cargo not identified
    • Not independently replicated at time of publication
  5. 2012 Medium

    Showing that ER-localized BNIP1 induces mitochondrial fragmentation through BH3-dependent Drp1 upregulation and translocation revealed a non-cell-autonomous mechanism by which ER-resident BNIP1 remodels mitochondria.

    Evidence Overexpression of wild-type and BH3-mutant BNIP1, live-cell imaging of mitochondrial morphology, Bcl-2 epistasis

    PMID:22020994

    Open questions at the time
    • Mechanism connecting BNIP1 BH3 domain to Drp1 transcriptional upregulation unknown
    • Overexpression system limits physiological interpretation
  6. 2013 High

    Two parallel advances — RNF186-mediated K29/K63 polyubiquitination promoting ER-stress apoptosis, and zebrafish genetic epistasis showing BH3-dependent photoreceptor death upon β-SNAP loss — convergently established that BNIP1 senses SNARE complex dysfunction and transduces it into apoptosis in vivo.

    Evidence RNF186: co-IP, ubiquitination assay, calcium imaging in cultured cells; Zebrafish: β-snap mutant with bnip1 knockdown rescue, vesicular transport assays

    PMID:23725763 PMID:23896122

    Open questions at the time
    • Whether RNF186 and β-SNAP pathways converge on the same apoptotic mechanism unclear
    • Endogenous ER stress conditions that activate RNF186–BNIP1 axis not defined
  7. 2019 Medium

    Drosophila loss-of-function studies revealed that the BNIP1 ortholog Sec20, together with Syntaxin-18 but independently of other retrograde transport SNAREs, is required for lysosomal acidification and autophagic vesicle clearance, separating its autophagy role from canonical Golgi-to-ER transport.

    Evidence Drosophila fat body and nephrocyte Sec20 knockdown, autophagic vesicle accumulation, lysosomal acidification, genetic epistasis with Use1/Sec22/Zw10

    PMID:31344970

    Open questions at the time
    • Mammalian validation of autophagy-specific versus retrograde transport functions not yet performed
    • Mechanism of BNIP1/Stx18-dependent lysosomal acidification not resolved
  8. 2020 Medium

    Temporal analysis in zebrafish showed BNIP1-dependent apoptosis is triggered specifically during high vesicular transport load (outer segment growth), positioning BNIP1 as a sensor of excessive ER–Golgi trafficking stress rather than a constitutive death effector.

    Evidence Zebrafish β-snap1 mutant with BNip1 knockdown, Ift88/Kif3b knockdown, rapamycin/mTOR inhibition, developmental timing of photoreceptor death

    PMID:33060680

    Open questions at the time
    • Whether this trafficking-stress-sensing role extends to mammalian tissues unknown
    • Direct molecular mechanism of transport load detection not identified
  9. 2022 Medium

    Identification of a hypomorphic BNIP1 variant causing spondylo-epiphyseal dysplasia in humans, with a specific block in autophagic flux at the autolysosome stage, established BNIP1 as essential for autophagy completion and skeletal homeostasis in humans.

    Evidence Patient fibroblast analysis with LC3B immunofluorescence/immunoblotting, bafilomycin A1 flux assay, lysosome positioning assay

    PMID:35266227

    Open questions at the time
    • Whether the skeletal phenotype results from autophagy defect, trafficking defect, or both is not resolved
    • Rescue experiments with wild-type BNIP1 not reported
    • Number of independent families limited

Open questions

Synthesis pass · forward-looking unresolved questions
  • The molecular mechanism by which BNIP1 promotes autolysosome maturation/lysosomal acidification — and whether this is SNARE-dependent or BH3-dependent — remains unresolved, as does the structural basis for α-SNAP competition at the BH3 domain and the physiological signals that switch BNIP1 between trafficking, autophagy, and apoptotic modes.
  • No structural model of BNIP1 in the syntaxin-18 SNARE complex
  • Autophagy versus retrograde transport functions not genetically separated in mammals
  • Endogenous signals regulating BNIP1 ubiquitination by RNF185/RNF186 unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 2
Localization
GO:0005783 endoplasmic reticulum 3
Pathway
R-HSA-5357801 Programmed Cell Death 3 R-HSA-9612973 Autophagy 3 R-HSA-5653656 Vesicle-mediated transport 2
Partners
BCL2BCL2L1DNM1LNAPARNF185RNF186SQSTM1STX18
Complex memberships
Syntaxin-18 SNARE complex

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2004 BNIP1 is a component of the syntaxin 18 SNARE complex at the endoplasmic reticulum and participates in ER network formation. A conserved leucine in the BH3 domain is required for both apoptosis induction and binding to alpha-SNAP (an NSF/SNARE adaptor), suggesting alpha-SNAP competes with antiapoptotic proteins for the BH3 domain to suppress apoptosis. Co-immunoprecipitation, functional overexpression/knockdown assays, mutagenesis of BH3 domain, staurosporine-induced apoptosis assay The EMBO journal High 15272311
2000 BNIP1 is a BH3-only pro-apoptotic protein; its BH3 domain is the functional apoptosis effector domain, as BH3 deletions abolish apoptotic activity and substitution of BNIP1 BH3 into BAX restores BAX apoptotic activity. BNIP1 also binds BCL-XL via the BH3 domain and a second N-terminal binding motif. Transient transfection, deletion/substitution mutagenesis, apoptosis assays, heterodimerization/interaction assays Oncogene High 10822388
2011 RNF185, a mitochondrial ubiquitin E3 ligase, polyubiquitinates BNIP1 via K63-linked chains. This polyubiquitinated BNIP1 recruits the autophagy receptor p62 (which binds both ubiquitin and LC3), linking BNIP1 ubiquitination to selective mitochondrial autophagy. Co-immunoprecipitation, in vivo ubiquitination assay, immunofluorescence colocalization, LC3 accumulation assay PloS one Medium 21931693
2013 RNF186, an ER-localized RING finger E3 ligase, polyubiquitinates BNIP1 via K29- and K63-linked chains, promoting BNIP1 translocation to mitochondria and ER stress-associated apoptotic signaling; BNIP1 knockdown attenuates RNF186-induced ER stress signals. Co-immunoprecipitation, in vivo ubiquitination assay, knockdown/overexpression, immunofluorescence, calcium imaging Cellular signalling Medium 23896122
1999 BNIP1 splice variants interact with BCL2 and BCL2L1 (BCL-XL) through a BH3-independent mechanism, and BNIP1 variants cannot interact with BAX, indicating a distinct binding mode from canonical BH3-only proteins. In vitro protein-protein interaction assays, PCR/EST database identification of splice variants FEBS letters Medium 10217402
2013 BNip1 (zebrafish ortholog) functions as a t-SNARE component of the syntaxin-18 SNARE complex regulating retrograde Golgi-to-ER transport, and mediates photoreceptor apoptosis when β-SNAP fails to disassemble the syntaxin-18 cis-SNARE complex; apoptosis requires the BH3 domain of BNip1. Genetic zebrafish β-snap mutant analysis, epistasis (bnip1 knockdown rescues apoptosis), immunofluorescence, vesicular transport assays Developmental cell High 23725763
2012 BNIP1 expression at the ER induces mitochondrial fragmentation in a BH3 domain-dependent manner, acting through upregulation of Drp1 expression and its mitochondrial translocation; Bcl-2 overexpression abrogates both Drp1 translocation and mitochondrial fission. Overexpression of BNIP1 and BH3-mutant constructs, live-cell imaging of mitochondrial morphology, immunofluorescence of Drp1 localization, Bcl-2 epistasis Journal of cellular physiology Medium 22020994
2017 A MTD-like motif (B1MLM) in BNIP1 conjugated to a cell-penetrating peptide induces necrosis via an intracellular calcium spike, mitochondrial ROS generation, and mitochondrial fragmentation, implicating this domain in calcium-mediated cell death. Cell-penetrating peptide delivery of B1MLM peptide, calcium imaging, ROS measurement, mitochondrial morphology assay Biochemical and biophysical research communications Low 29222049
2022 A hypomorphic BNIP1 variant in humans (~50% reduction in BNIP1 protein) causes a block in autophagic flux at the terminal autolysosome formation/clearance stage, with increased LC3B-positive structures, altered lysosome positioning (peripheral shift), and results in spondylo-epiphyseal dysplasia. Patient fibroblast analysis, immunofluorescence and immunoblotting for LC3B, bafilomycin A1 flux assay, lysosome positioning assay Human mutation Medium 35266227
2019 Drosophila Sec20 (BNIP1 ortholog) is required for autophagic vesicle clearance and lysosomal acidification during starvation-induced autophagy, and for endolysosomal maturation in nephrocytes; this function is shared with its partner Syntaxin 18 but is independent of the Golgi-ER retrograde transport partners Use1, Sec22, and Zw10. Drosophila fat cell and nephrocyte Sec20 loss-of-function, autophagic vesicle accumulation assay, lysosomal acidification assay, genetic epistasis with partner SNAREs Cells Medium 31344970
2020 BNip1-dependent photoreceptor apoptosis in zebrafish β-snap1 mutants occurs specifically during the outer segment (OS) growth period; inhibiting OS protein transport (Ift88/Kif3b knockdown) or protein synthesis (rapamycin/mTOR inhibition) rescues apoptosis, indicating BNip1 monitors excessive vesicular transport as a stress sensor. Zebrafish β-snap1 mutant with BNip1 knockdown epistasis, transient β-SNAP1 rescue, Ift88/Kif3b knockdown, rapamycin treatment, photoreceptor apoptosis quantification Scientific reports Medium 33060680

Source papers

Stage 0 corpus · 42 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2008 NIP1;1, an aquaporin homolog, determines the arsenite sensitivity of Arabidopsis thaliana. The Journal of biological chemistry 150 19029297
2004 Interactions of eukaryotic translation initiation factor 3 (eIF3) subunit NIP1/c with eIF1 and eIF5 promote preinitiation complex assembly and regulate start codon selection. Molecular and cellular biology 140 15485912
1995 The race-specific elicitor, NIP1, from the barley pathogen, Rhynchosporium secalis, determines avirulence on host plants of the Rrs1 resistance genotype. The EMBO journal 138 7556057
2003 The yeast eIF3 subunits TIF32/a, NIP1/c, and eIF5 make critical connections with the 40S ribosome in vivo. Genes & development 128 12651896
2004 Involvement of BNIP1 in apoptosis and endoplasmic reticulum membrane fusion. The EMBO journal 109 15272311
2017 NIP1;2 is a plasma membrane-localized transporter mediating aluminum uptake, translocation, and tolerance in Arabidopsis. Proceedings of the National Academy of Sciences of the United States of America 100 28439024
1992 The Saccharomyces cerevisiae SEC20 gene encodes a membrane glycoprotein which is sorted by the HDEL retrieval system. The EMBO journal 85 1537327
2011 RNF185, a novel mitochondrial ubiquitin E3 ligase, regulates autophagy through interaction with BNIP1. PloS one 84 21931693
2004 Molecular population genetic analysis differentiates two virulence mechanisms of the fungal avirulence gene NIP1. Molecular plant-microbe interactions : MPMI 81 15497404
2011 The eIF3c/NIP1 PCI domain interacts with RNA and RACK1/ASC1 and promotes assembly of translation preinitiation complexes. Nucleic acids research 63 22123745
1993 Cultivar-specific elicitation of barley defense reactions by the phytotoxic peptide NIP1 from Rhynchosporium secalis. Molecular plant-microbe interactions : MPMI 47 8118056
2008 Molecular characterization of the role of the Schizosaccharomyces pombe nip1+/ctp1+ gene in DNA double-strand break repair in association with the Mre11-Rad50-Nbs1 complex. Molecular and cellular biology 41 18378696
2019 Variation in Membrane Trafficking Linked to SNARE AtSYP51 Interaction With Aquaporin NIP1;1. Frontiers in plant science 36 30687352
2013 A novel RING finger E3 ligase RNF186 regulate ER stress-mediated apoptosis through interaction with BNip1. Cellular signalling 36 23896122
1997 The Sec20/Tip20p complex is involved in ER retrieval of dilysine-tagged proteins. European journal of cell biology 35 9208221
2012 Functional characterization of the role of the N-terminal domain of the c/Nip1 subunit of eukaryotic initiation factor 3 (eIF3) in AUG recognition. The Journal of biological chemistry 30 22718758
1992 NIP1, a gene required for nuclear transport in yeast. Proceedings of the National Academy of Sciences of the United States of America 30 1332047
2017 Genome-wide Association Study Reveals that the Aquaporin NIP1;1 Contributes to Variation in Hydrogen Peroxide Sensitivity in Arabidopsis thaliana. Molecular plant 29 28712931
2000 Functional identification of the apoptosis effector BH3 domain in cellular protein BNIP1. Oncogene 25 10822388
2013 The BH3-only SNARE BNip1 mediates photoreceptor apoptosis in response to vesicular fusion defects. Developmental cell 24 23725763
1999 Novel BNIP1 variants and their interaction with BCL2 family members. FEBS letters 23 10217402
2012 Endoplasmic reticulum-specific BH3-only protein BNIP1 induces mitochondrial fragmentation in a Bcl-2- and Drp1-dependent manner. Journal of cellular physiology 22 22020994
2008 Mossbauer evidence for an exchange-coupled {[Fe4S4]1+ Nip1+} A-cluster in isolated alpha subunits of acetyl-coenzyme A synthase/carbon monoxide dehydrogenase. Journal of the American Chemical Society 22 18459773
2009 NIP1/DUOXA1 expression in epithelial breast cancer cells: regulation of cell adhesion and actin dynamics. Breast cancer research and treatment 19 19322654
2007 A single binding site mediates resistance- and disease-associated activities of the effector protein NIP1 from the barley pathogen Rhynchosporium secalis. Plant physiology 19 17478637
2019 The emergence of the multi-species NIP1 effector in Rhynchosporium was accompanied by high rates of gene duplications and losses. Environmental microbiology 17 30838748
2003 Solution structure of the plant disease resistance-triggering protein NIP1 from the fungus Rhynchosporium secalis shows a novel beta-sheet fold. The Journal of biological chemistry 16 12944393
2004 NIP1/XB51/NECAB3 is a potential substrate of Nek2, suggesting specific roles of Nek2 in Golgi. Experimental cell research 15 14697346
2001 Divergence of eukaryotic secretory components: the Candida albicans homolog of the Saccharomyces cerevisiae ++Sec20 protein is N terminally truncated, and its levels determine antifungal drug resistance and growth. Journal of bacteriology 15 11114899
2018 Aluminum-activated root malate and citrate exudation is independent of NIP1;2-facilitated root-cell-wall aluminum removal in Arabidopsis. Plant signaling & behavior 14 29293394
2022 Evaluation of Dittrichia viscosa Aquaporin Nip1.1 Gene as Marker for Arsenic-Tolerant Plant Selection. Plants (Basel, Switzerland) 10 35956446
2019 BNIP1 inhibits cell proliferation, migration and invasion, and promotes apoptosis by mTOR in cervical cancer cells. European review for medical and pharmacological sciences 10 30840260
2019 Sec20 is Required for Autophagic and Endocytic Degradation Independent of Golgi-ER Retrograde Transport. Cells 9 31344970
2022 A homozygous hypomorphic BNIP1 variant causes an increase in autophagosomes and reduced autophagic flux and results in a spondylo-epiphyseal dysplasia. Human mutation 8 35266227
1999 Heterologous expression of the avirulence gene product, NIP1, from the barley pathogen Rhynchosporium secalis. Protein expression and purification 8 10497070
2001 The yeast SEC20 gene is required for N- and O-glycosylation in the Golgi. Evidence that impaired glycosylation does not correlate with the secretory defect. The Journal of biological chemistry 7 11477110
2024 ARR1 and ARR12 modulate arsenite toxicity responses in Arabidopsis roots by transcriptionally controlling the actions of NIP1;1 and NIP6;1. The Plant journal : for cell and molecular biology 5 39378328
2020 β-SNAP activity in the outer segment growth period is critical for preventing BNip1-dependent apoptosis in zebrafish photoreceptors. Scientific reports 4 33060680
2024 Generation of a competing endogenous RNA network and validation of BNIP1 expression in the lung of irradiated mice. Translational oncology 3 38906065
2018 Involvement of aquaporin NIP1;1 in the contrasting tolerance response to root hypoxia in Prunus rootstocks. Journal of plant physiology 3 29842998
2017 MTD-like motif of a BH3-only protein, BNIP1, induces necrosis accompanied by an intracellular calcium spike. Biochemical and biophysical research communications 3 29222049
2024 Retraction Note: BNIP1 inhibits cell proliferation, migration and invasion, and promotes apoptosis by mTOR in cervical cancer cells. European review for medical and pharmacological sciences 0 38766787