Affinage

IER3IP1

Immediate early response 3-interacting protein 1 · UniProt Q9Y5U9

Length
82 aa
Mass
9.0 kDa
Annotated
2026-06-10
13 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

IER3IP1 is a small endoplasmic reticulum membrane protein that supports the secretory pathway by facilitating ER-to-Golgi trafficking of specific cargo and by restraining ER stress (PMID:15276200, PMID:39115595). It is required for the efficient export of secreted and membrane proteins, and its loss causes mistrafficking of neuronal development and survival factors (FGFR3, UNC5B, SEMA4D), distension of ER membranes, increased lysosomal activity, and aberrant secretion of ER-resident chaperones (PMID:39115595). In pancreatic beta-cells, IER3IP1 is needed for ER-to-Golgi transport of proinsulin, and its loss reduces proinsulin trafficking, drives proinsulin misfolding with accumulation of ER chaperones (PDI, ERO1, BiP, P58IPK), and triggers ER stress and beta-cell apoptosis through a Bim/Bcl-xL imbalance, establishing impaired proinsulin trafficking as the basis of IER3IP1-associated insulin-deficient diabetes (PMID:28915629, PMID:36322741, PMID:39441964). IER3IP1 forms a complex with the Golgi transmembrane protein TMEM167A and limits IRE1α/XBP1-mediated unfolded protein response activation, a function relevant to B cell development (PMID:37934820). Beyond the secretory pathway, IER3IP1 localizes to and physically interacts with Rab11 recycling-endosome vesicles and is required for cytokinesis, with pathogenic mutations disrupting its Rab11-vesicle localization (PMID:40991444). Its transcription is driven by Sp1 and induced by TNF-α via an NF-κB element (PMID:19885854).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2004 Medium

    Established the basic identity and subcellular home of IER3IP1, defining it as an ER-resident membrane protein and providing the structural starting point for all later trafficking work.

    Evidence cDNA cloning, ER-marker co-localization, and transmembrane/domain analysis in HepG2 cells

    PMID:15276200

    Open questions at the time
    • G-patch domain function in RNA binding never tested experimentally
    • No interacting partners or cargo identified at this stage
    • Topology and orientation in the ER membrane not resolved
  2. 2010 Medium

    Defined the transcriptional control of IER3IP1, linking its expression to Sp1 basal activity and inflammatory TNF-α/NF-κB signaling.

    Evidence Promoter deletion/mutation analysis with Sp1 site mapping and TNF-α/NF-κB reporter assays

    PMID:19885854

    Open questions at the time
    • Physiological context in which TNF-α induction is relevant not established
    • No link drawn between transcriptional regulation and trafficking function
  3. 2017 Medium

    Connected IER3IP1 loss to beta-cell apoptosis through a defined Bim/Bcl-xL axis, providing the first mechanistic readout of why IER3IP1 deficiency damages beta-cells.

    Evidence shRNA knockdown in MIN6 cells with apoptosis assays, UPR/Bim/Bcl-xL westerns, and rescue by Bim knockdown or Bcl-xL overexpression

    PMID:28915629

    Open questions at the time
    • Upstream cause of apoptosis (trafficking defect vs. direct UPR effect) not resolved
    • Reported suppression of IRE1/PERK arms here contrasts with later UPR-limiting findings
    • Single cell line, no in vivo validation
  4. 2022 High

    Demonstrated in vivo that beta-cell IER3IP1 is required to prevent ER distension, proinsulin misfolding, and insulin-deficient diabetes, anchoring the human disease phenotype in a genetic mouse model.

    Evidence Constitutive and inducible beta-cell-specific knockout mice with EM, islet transcriptomics, and proliferation/maturation assays

    PMID:36322741

    Open questions at the time
    • Molecular trafficking step impaired not directly measured here
    • Whether ER distension is cause or consequence of misfolding unresolved
  5. 2023 High

    Identified TMEM167A as a physical partner and recast IER3IP1 as a limiter of IRE1α/XBP1 UPR signaling, extending its role beyond beta-cells to cell-intrinsic B cell development.

    Evidence ENU forward genetic screen yielding a hypomorphic allele, co-IP complex identification, UPR marker analysis, and hematopoietic transplantation

    PMID:37934820

    Open questions at the time
    • Whether the TMEM167A complex mediates trafficking, UPR control, or both not separated
    • Structural basis of the IER3IP1–TMEM167A interaction unknown
  6. 2024 High

    Defined IER3IP1 as a selective ER-to-Golgi transport factor by identifying specific mistrafficked cargo and machinery, explaining the neurodevelopmental phenotype.

    Evidence Secretome and cell-surface proteomics, ER morphology and lysosomal activity assays, and in-utero knockdown in mouse embryo brains

    PMID:39115595

    Open questions at the time
    • Mechanism of cargo selectivity not defined
    • Direct binding of IER3IP1 to the identified cargo not shown
  7. 2025 High

    Pinpointed impaired proinsulin ER-to-Golgi trafficking as the molecular mechanism of IER3IP1-mutation diabetes in a human stem cell-derived beta-cell system.

    Evidence CRISPR editing of human ESCs differentiated to islet lineages, quantitative ER-to-Golgi trafficking assay, ER stress markers, and in vivo transplantation

    PMID:39441964

    Open questions at the time
    • Whether IER3IP1 directly packages proinsulin into transport carriers not established
    • Quantitative relationship between trafficking reduction and ER stress not modeled
  8. 2025 High

    Revealed a distinct Rab11-dependent role for IER3IP1 in cytokinesis, showing it localizes to and binds Rab11 vesicles and that disease mutations disrupt this localization, with cross-species rescue confirming conserved function.

    Evidence Drosophila genetic screen and human-gene rescue, Rab11 co-IP, live imaging of Rab11 vesicles, human-cell cytokinesis assays, and pathogenic mutation localization analysis

    PMID:40991444

    Open questions at the time
    • How a single ER membrane protein bridges secretory trafficking and Rab11 recycling-endosome cytokinesis function unresolved
    • Whether Rab11 binding is direct or vesicle-membrane-mediated not distinguished

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unknown how IER3IP1 mechanistically reconciles its dual roles in selective ER-to-Golgi cargo export and Rab11-vesicle-dependent cytokinesis, and what molecular feature confers cargo specificity.
  • No structure of IER3IP1 or its complexes
  • No defined cargo-recognition mechanism
  • Relationship between TMEM167A complex and Rab11 association unexplored

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 1
Localization
GO:0005783 endoplasmic reticulum 3 GO:0031410 cytoplasmic vesicle 1
Pathway
R-HSA-5653656 Vesicle-mediated transport 2 R-HSA-1640170 Cell Cycle 1 R-HSA-5357801 Programmed Cell Death 1 R-HSA-8953897 Cellular responses to stimuli 1
Partners
RAB11TMEM167A

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2004 IER3IP1 is a novel endoplasmic reticulum membrane protein containing a G-patch domain (suggested to be involved in RNA binding) and a C-terminal transmembrane domain; it localizes to the ER of HepG2 cells, confirmed by co-localization with an ER-specific marker. cDNA cloning, northern blot, co-localization with ER marker in HepG2 cells, transmembrane domain analysis Gene Medium 15276200
2010 IER3IP1 gene transcription is activated by Sp1 binding to its basal promoter (-298/-59 region) and is induced by TNF-alpha through an NF-kappaB responsive element in the IER3IP1 promoter. Promoter deletion analysis, mutation analysis of Sp1 site, TNF-alpha treatment with NF-kappaB reporter assays Cell biochemistry and function Medium 19885854
2017 IER3IP1 knockdown in MIN6 beta-cells induces apoptosis associated with increased Bim and decreased Bcl-xL; knockdown of Bim or overexpression of Bcl-xL rescues this apoptosis. IER3IP1 suppression also impairs the IRE1 and PERK arms of the unfolded protein response (UPR) and decreases cell proliferation. shRNA knockdown in MIN6 cells, apoptosis assays, western blot for Bim/Bcl-xL/UPR markers, rescue experiments with Bim knockdown and Bcl-xL overexpression Oncotarget Medium 28915629
2022 Constitutive or inducible beta-cell-specific deletion of IER3IP1 in mice causes severe early-onset insulin-deficient diabetes, markedly dilated beta-cell ER, increased proinsulin misfolding, elevated ER chaperones (PDI, ERO1, BiP, P58IPK), impaired beta-cell maturation and proliferation, and increased nuclear chromatin condensation. Conditional/inducible knockout mouse models (IER3IP1-βKO, IER3IP1-iβKO), electron microscopy of ER, islet transcriptome analysis, qRT-PCR, multiple independent approaches for beta-cell maturation/proliferation Proceedings of the National Academy of Sciences of the United States of America High 36322741
2023 IER3IP1 forms a complex with the Golgi transmembrane protein TMEM167A (Golgi transmembrane protein 167A) and limits activation of the unfolded protein response mediated by IRE1alpha and XBP1 in B cells; loss of IER3IP1 impairs B cell development in a hematopoietic-intrinsic manner. Forward genetic screen (ENU mutagenesis in mice), identification of hypomorphic Ier3ip1 allele, co-immunoprecipitation/complex formation assay, UPR marker analysis in B cells, hematopoietic transplantation to establish cell-intrinsic role Proceedings of the National Academy of Sciences of the United States of America High 37934820
2024 IER3IP1 plays a non-essential role in ER-to-Golgi transport; its absence causes mistrafficking of neuronal development/survival proteins (FGFR3, UNC5B, SEMA4D), distension of ER membranes, increased lysosomal activity, compromised trafficking of cargo receptor ERGIC53 and KDEL-receptor 2, and anomalous secretion of ER-localized chaperones. In-utero knockdown of Ier3ip1 in mouse embryo brains causes morphological phenotype in newborn neurons. Secretome and cell-surface proteomics, in-utero knockdown of Ier3ip1 in mouse embryo brains, ER morphology analysis, lysosomal activity assays Cellular and molecular life sciences : CMLS High 39115595
2025 Loss of IER3IP1 causes a ~3-fold reduction in ER-to-Golgi trafficking of proinsulin in human stem cell-derived beta-cells, leading to beta-cell dysfunction in vitro and in vivo, and triggers increased ER stress markers; this identifies impaired proinsulin trafficking as the molecular mechanism underlying IER3IP1-mutation-associated diabetes. Targeted genome editing (CRISPR) in human embryonic stem cells, differentiation into pancreatic islet lineages, ER-to-Golgi trafficking assay, in vivo transplantation, ER stress marker analysis Diabetes High 39441964
2025 IER3IP1 (Drosophila ortholog: Inseparable/Insep) is required for cytokinesis in neuroblasts; loss leads to cytokinesis failure and excessive accumulation of Rab11 vesicles in the cytoplasm. IER3IP1 localizes to Rab11 vesicles and physically interacts with Rab11. Pathogenic mutations in IER3IP1 perturb its localization to Rab11 vesicles. The Drosophila phenotype (small brains, early larval lethality) is rescued by expressing human IER3IP1, confirming functional conservation. Drosophila genetic screen, loss-of-function analysis, rescue with human IER3IP1, live imaging of Rab11 vesicles, co-immunoprecipitation with Rab11, IER3IP1 knockdown in human cells with cytokinesis assay, pathogenic mutation analysis of localization Proceedings of the National Academy of Sciences of the United States of America High 40991444

Source papers

Stage 0 corpus · 13 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 A homozygous IER3IP1 mutation causes microcephaly with simplified gyral pattern, epilepsy, and permanent neonatal diabetes syndrome (MEDS). American journal of medical genetics. Part A 43 22991235
2013 Microcephaly, epilepsy, and neonatal diabetes due to compound heterozygous mutations in IER3IP1: insights into the natural history of a rare disorder. Pediatric diabetes 39 24138066
2004 Cloning and characterization of a novel endoplasmic reticulum localized G-patch domain protein, IER3IP1. Gene 20 15276200
2022 IER3IP1 is critical for maintaining glucose homeostasis through regulating the endoplasmic reticulum function and survival of β cells. Proceedings of the National Academy of Sciences of the United States of America 16 36322741
2017 IER3IP1 deficiency leads to increased β-cell death and decreased β-cell proliferation. Oncotarget 15 28915629
2023 Essential requirement for IER3IP1 in B cell development. Proceedings of the National Academy of Sciences of the United States of America 8 37934820
2024 IER3IP1-mutations cause microcephaly by selective inhibition of ER-Golgi transport. Cellular and molecular life sciences : CMLS 7 39115595
2022 A New Variant of the IER3IP1 Gene: The First Case of Microcephaly, Epilepsy, and Diabetes Syndrome 1 from Turkey. Journal of clinical research in pediatric endocrinology 6 36416459
2025 IER3IP1 Mutations Cause Neonatal Diabetes Due to Impaired Proinsulin Trafficking. Diabetes 5 39441964
2010 Transcriptional regulation of IER3IP1 gene by tumor necrosis factor-alpha and Sp family proteins. Cell biochemistry and function 2 19885854
2007 [The expression of IER3IP1 gene in K562 cells treated by matrine and its effect on the cell growth]. Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi 1 18476594
2025 Inseparable/IER3IP1 are essential for cytokinesis in Drosophila neuroblasts and human cells. Proceedings of the National Academy of Sciences of the United States of America 0 40991444
2025 Microcephaly, Epilepsy, and Diabetes Syndrome 1: A Moroccan Case Report of Novel Compound Heterozygous IER3IP1 Mutations and Literature Review. Balkan journal of medical genetics : BJMG 0 41200581

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