Affinage

MCUR1

Mitochondrial calcium uniporter regulator 1 · UniProt Q96AQ8

Length
359 aa
Mass
39.7 kDa
Annotated
2026-06-10
13 papers in source corpus 11 papers cited in narrative 11 extracted findings
Cross-family judge vs UniProt: tie faithfulness: 8/8 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MCUR1 (CCDC90A) is an integral inner mitochondrial membrane coiled-coil protein that acts as a scaffold for the mitochondrial calcium uniporter and as a broader regulator of mitochondrial metabolic homeostasis (PMID:23178883, PMID:27184846). It physically binds MCU and EMRE through minimal coiled-coil interaction domains, forming a heterooligomeric complex required for MCU-dependent, ruthenium-red-sensitive mitochondrial Ca2+ uptake and for normal IMCU current (PMID:23178883, PMID:27184846). The MCUR1 head domain directly engages MCU and is destabilized upon Ca2+ binding, within a conserved head-neck-stalk-anchor architecture shared with its paralog CCDC90B and prokaryotic relatives (PMID:30612859). MCUR1 sets the Ca2+ threshold for mitochondrial permeability transition, such that its loss raises the threshold and confers resistance to Ca2+ overload (PMID:26976564). Functionally, MCUR1-dependent Ca2+ uptake supports oxidative phosphorylation and cellular ATP, and its loss disrupts bioenergetics and activates AMPK-dependent autophagy (PMID:23178883, PMID:27184846); one study links MCUR1 loss specifically to a cytochrome c oxidase assembly defect and reduced membrane potential, arguing its effect on Ca2+ uptake is at least partly indirect (PMID:25565209). Beyond Ca2+ regulation, MCUR1 and CCDC90B form an MCUR1-stabilized hetero-oligomeric scaffold whose conserved function in proline, lipid, and amino acid metabolism is retained in yeast lacking MCU and rescuable by human MCUR1 [PMID:32978391, PMID:bio_10.1101_2025.10.14.682030]. In hepatocellular carcinoma, MCUR1-driven mitochondrial Ca2+ uptake elevates ROS to promote survival via AKT/MDM2-mediated p53 degradation and EMT/metastasis via the Nrf2/Notch1/Snail axis (PMID:30909929, PMID:28938844). A homozygous MCUR1 nonsense mutation causes autophagic vacuolar myopathy in humans, with compromised Ca2+ uptake and increased autophagic flux but no change in MCU complex assembly or localization, establishing that MCUR1 promotes MCU activity without being required for complex stability (PMID:42087238).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2012 High

    Established MCUR1 as a physical MCU partner required for mitochondrial Ca2+ uptake, defining it as a positive regulator of the uniporter and linking its loss to bioenergetic failure and autophagy.

    Evidence Co-IP of MCU-MCUR1 with siRNA knockdown, Ca2+ uptake assays in intact/permeabilized cells, ruthenium red sensitivity, ATP and AMPK assays

    PMID:23178883

    Open questions at the time
    • Did not resolve whether the Ca2+ uptake defect is direct or secondary to bioenergetic loss
    • No structural basis for MCU binding
    • Did not test EMRE involvement
  2. 2015 High

    Challenged the direct-regulator model by attributing MCUR1's effect on Ca2+ uptake to a cytochrome c oxidase assembly defect and lowered membrane potential, and showed the function is evolutionarily conserved in yeast.

    Evidence siRNA in human fibroblasts, COX assembly and membrane potential assays, yeast fmp32 deletion, cDNA rescue in patient fibroblasts

    PMID:25565209

    Open questions at the time
    • Did not reconcile COX-defect model with direct MCU binding data
    • Mechanism linking MCUR1 to COX assembly unresolved
  3. 2016 High

    Defined MCUR1 as a coiled-coil scaffold for MCU complex assembly and showed it regulates the Ca2+ threshold for permeability transition, connecting MCUR1 to both uniporter function and cell survival.

    Evidence Domain mapping of coiled-coil interactions, IMCU electrophysiology, Co-IP with MCU/EMRE, conditional knockout in cardiomyocytes and endothelial cells; Drosophila complementation and mPT Ca2+ titration assays

    PMID:26976564 PMID:27184846

    Open questions at the time
    • Structural detail of the heterooligomer not resolved
    • Whether scaffold and mPT-threshold roles are mechanistically separable unclear
  4. 2019 High

    Provided the structural framework for MCUR1, defining a conserved head-neck-stalk-anchor architecture, a head domain that directly binds MCU and is Ca2+-destabilized, and a paralog relationship with CCDC90B.

    Evidence Crystal structures of CCDC90B head domain and archaeal Kcr-0859, MCUR1 domain mutagenesis, Ca2+ binding/destabilization assays

    PMID:30612859

    Open questions at the time
    • No full-length MCUR1 structure
    • No co-structure of MCUR1 with MCU
    • Functional consequence of Ca2+-induced destabilization in cells untested
  5. 2017 Medium

    Placed MCUR1-driven Ca2+ uptake within a cancer survival circuit, showing it elevates mitochondrial ROS to drive AKT/MDM2-mediated p53 degradation and suppress apoptosis.

    Evidence MCUR1 knockdown/overexpression in HCC cells, Ca2+ and ROS measurements, p53 degradation and AKT/MDM2 analysis, xenograft assays, parvalbumin buffering

    PMID:28938844

    Open questions at the time
    • No direct biochemical binding linking MCUR1 to the AKT/MDM2 axis
    • Pathway placement inferred from pharmacological buffering
  6. 2019 Medium

    Extended the MCUR1-ROS axis to EMT and metastasis, showing MCUR1-dependent Ca2+ uptake activates Nrf2/Notch1/Snail signaling to promote invasion.

    Evidence MCUR1 knockdown/overexpression in HCC, EMT marker staining, invasion/metastasis assays, ROS measurement, chemical and parvalbumin pathway inhibition

    PMID:30909929

    Open questions at the time
    • No direct molecular binding assay
    • Causality relies on inhibitor and buffering experiments
  7. 2020 High

    Revealed a Ca2+-independent metabolic scaffold function by showing yeast homologs Put6/Put7 form an inner-membrane hetero-oligomer governing proline metabolism, rescuable by human MCUR1.

    Evidence Put6/Put7 deletion in S. cerevisiae, mitochondrial fractionation, complex characterization, proline utilization, metabolomics, redox assays, heterologous human MCUR1 complementation

    PMID:32978391

    Open questions at the time
    • Direct substrate/enzyme partners of the scaffold not defined
    • Mechanism connecting scaffold to proline metabolism unresolved
    • Conservation of proline role in human cells not directly tested
  8. 2025 Medium

    Connected MCUR1 to physiology by showing its loss raises cytosolic Ca2+ and limits erythropoiesis through the CAMKK2-AMPK-mTOR axis, with a human eQTL variant tuning MCUR1 expression in highlanders.

    Evidence MCUR1 knockdown with scRNA-seq, mitochondrial/cytosolic Ca2+ measurements, pharmacological pathway dissection, erythropoiesis assays, whole-genome sequencing and eQTL analysis

    PMID:40043709

    Open questions at the time
    • Pathway placement partly inhibitor-dependent
    • Direct link from cytosolic Ca2+ to CAMKK2 not biochemically shown
  9. 2026 Medium

    Established MCUR1 as a Mendelian disease gene, showing a homozygous nonsense mutation causes autophagic vacuolar myopathy with impaired Ca2+ uptake but intact MCU assembly, separating MCUR1's activating role from a structural requirement.

    Evidence Patient fibroblast and muscle biopsy analysis, Ca2+ uptake and autophagy flux assays, Western blot for MCU components, histology, membrane potential measurement

    PMID:42087238

    Open questions at the time
    • Single patient case
    • Mechanism by which MCUR1 promotes MCU activity without affecting assembly not defined
  10. 2025 Medium

    Defined the MCUR1-CCDC90B hetero-oligomer as MCUR1-stabilized and demonstrated a conserved, MCU-independent scaffold role in lipid and amino acid metabolism underlying the human disease phenotype.

    Evidence Complex stability/Co-IP assays, S. pombe deletion with human MCUR1 rescue, patient serum metabolomics and fibroblast functional assays (preprint)

    PMID:bio_10.1101_2025.10.14.682030

    Open questions at the time
    • Preprint not yet peer reviewed
    • Molecular substrates of the metabolic scaffold not identified
    • Mechanism of dominant-negative effect on CCDC90B unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • How MCUR1 mechanistically reconciles its direct MCU-scaffold role with its MCU-independent metabolic scaffold function — and which is primary in the human myopathy — remains unresolved.
  • No structure of MCUR1 bound to MCU or to CCDC90B
  • Direct enzymatic partners of the metabolic scaffold unidentified
  • Relative contributions of Ca2+ and metabolic functions to disease undetermined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0098772 molecular function regulator activity 3
Localization
GO:0005739 mitochondrion 3
Pathway
R-HSA-1430728 Metabolism 3 R-HSA-382551 Transport of small molecules 3 R-HSA-9612973 Autophagy 3
Partners
Complex memberships
MCU complex (uniporter)MCUR1-CCDC90B hetero-oligomer

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2012 MCUR1 (CCDC90A) is an integral inner mitochondrial membrane protein that physically binds to MCU and is required for ruthenium-red-sensitive, MCU-dependent mitochondrial Ca2+ uptake. MCUR1 knockdown abrogates Ca2+ uptake by energized mitochondria in intact and permeabilized cells without altering MCU localization. Loss of MCUR1 disrupts oxidative phosphorylation, lowers cellular ATP, and activates AMPK-dependent pro-survival autophagy. Co-immunoprecipitation (MCU-MCUR1 binding), siRNA knockdown with Ca2+ uptake assays in intact and permeabilized cells, ruthenium red sensitivity assays, ATP measurements, AMPK activation assays Nature cell biology High 23178883
2015 Suppression of CCDC90A (MCUR1) in human fibroblasts produces a specific cytochrome c oxidase (COX) assembly defect, resulting in decreased mitochondrial membrane potential and reduced mitochondrial Ca2+ uptake capacity. The yeast homolog Fmp32 deletion also causes COX deficiency, indicating the function is evolutionarily conserved. This study argues CCDC90A acts indirectly on Ca2+ uptake via membrane potential, not as a direct MCU regulator. siRNA knockdown in human fibroblasts, COX assembly assays, mitochondrial membrane potential measurements, Ca2+ uptake capacity assays, genetic deletion of yeast homolog fmp32, rescue with wild-type cDNA in COX-deficient patient fibroblasts Cell metabolism High 25565209
2016 MCUR1 functions as a scaffold factor for the MCU complex, binding both MCU and EMRE. Loss of MCUR1 in mouse cardiomyocytes and endothelial cells severely impairs mitochondrial Ca2+ uptake current (IMCU). The minimal coiled-coil domains of both MCU and MCUR1 are necessary for heterooligomeric complex formation. Loss of MCUR1 perturbs MCU complex assembly and impairs mitochondrial bioenergetics, cell proliferation, and migration while eliciting autophagy. Protein binding analyses identifying coiled-coil interaction domains, IMCU current measurements (electrophysiology), Co-IP of MCUR1 with MCU and EMRE, conditional genetic deletion in cardiomyocytes and endothelial cells, cell proliferation and migration assays Cell reports High 27184846
2016 MCUR1 expression regulates the Ca2+ threshold required for mitochondrial permeability transition (mPT). Expression of MCUR1 in Drosophila cells conferred mPT sensitivity to electrophoretic Ca2+ uptake; inhibiting MCUR1 in mammalian cells increased the Ca2+ threshold required to induce mPT. This resistance to Ca2+ overload improved cell survival. The effect was specific to Ca2+-induced permeability transition. Cross-species complementation (MCUR1 expression in Drosophila cells), MCUR1 knockdown in mammalian cells, mitochondrial permeability transition assays with Ca2+ titration, cell survival assays Proceedings of the National Academy of Sciences of the United States of America High 26976564
2019 The head domain of MCUR1 directly interacts with the mitochondrial calcium uniporter (MCU) and is destabilized upon Ca2+ binding. Crystal structures of the related CCDC90B head domain and archaeal Kcr-0859 reveal a conserved head-neck-stalk-anchor architecture with a β-layer neck. MCUR1 and CCDC90B are part of a heterogeneous group of trimeric membrane-anchored coiled-coil proteins conserved from prokaryotes to eukaryotic organelles. Crystal structure determination of CCDC90B head domain and archaeal Kcr-0859, domain deletion/mutagenesis studies of MCUR1, Ca2+ binding and destabilization assays, sequence analysis defining domain architecture Structure (London, England : 1993) High 30612859
2019 MCUR1-mediated mitochondrial Ca2+ uptake activates the ROS/Nrf2/Notch1 pathway, which drives EMT via Snail in hepatocellular carcinoma cells. MCUR1 promotes in vitro invasion and in vivo metastasis. Inhibition of ROS, mitochondrial Ca2+ uptake, Nrf2, or Notch1 suppresses MCUR1-induced EMT. Mitochondrial Ca2+-buffering with parvalbumin inhibits the pathway and MCUR1-induced EMT and metastasis. MCUR1 knockdown/overexpression in HCC cells, immunofluorescent staining for EMT markers, in vitro invasion assays, in vivo metastasis assays, ROS measurement, pathway inhibition with chemical inhibitors and parvalbumin treatment, Western blot Journal of experimental & clinical cancer research : CR Medium 30909929
2017 MCUR1-mediated mitochondrial Ca2+ uptake elevates mitochondrial ROS production, which drives AKT/MDM2-mediated P53 degradation to inhibit intrinsic apoptosis and promote HCC cell survival and proliferation. MCUR1 overexpression enhances MCU-dependent Ca2+ uptake; knockdown impairs it. Mitochondrial Ca2+ buffering with parvalbumin inhibits HCC cell growth. MCUR1 knockdown/overexpression in HCC cells, mitochondrial Ca2+ uptake measurements, ROS measurement, P53 degradation assays, AKT/MDM2 pathway analysis, in vivo xenograft assays (TUNEL, Ki67 staining), parvalbumin treatment Antioxidants & redox signaling Medium 28938844
2020 Yeast homologs of MCUR1, Put6 and Put7, form a large hetero-oligomeric complex tethered to the inner mitochondrial membrane and regulate mitochondrial proline metabolism. Loss of this complex perturbs mitochondrial proline homeostasis and cellular redox balance; cells lacking Put6 or Put7 cannot utilize proline. This defect is rescued by heterologous expression of human MCUR1, demonstrating functional conservation of MCUR1 homologs in mitochondrial metabolic scaffolding beyond Ca2+ regulation. Genetic deletion of Put6/Put7 in S. cerevisiae, mitochondrial fractionation, hetero-oligomeric complex characterization, proline utilization assays, metabolomics, redox assays, heterologous complementation with human MCUR1 Nature communications High 32978391
2025 MCUR1 knockdown reduces mitochondrial Ca2+ uptake and concomitantly increases cytosolic Ca2+, which reduces erythropoiesis via the CAMKK2-AMPK-mTOR signaling axis under both hypoxia and normoxia. A functional SNP (rs61644582) acts as an expression QTL reducing MCUR1 transcription, and attenuates erythropoiesis in Tibetan highlanders. MCUR1 knockdown with single-cell RNA sequencing, mitochondrial Ca2+ uptake measurements, cytosolic Ca2+ measurements, pharmacological inhibition of CAMKK2-AMPK-mTOR pathway components, erythropoiesis differentiation assays, whole-genome sequencing and eQTL analysis Cell genomics Medium 40043709
2026 A homozygous MCUR1 nonsense mutation in a human patient causes compromised mitochondrial Ca2+ uptake (stimulated by histamine or rising extracellular Ca2+), increased autophagic flux (LAMP2, LC3B markers), and autophagic vacuolar myopathy. Critically, MCUR1 loss-of-function does NOT alter MCU complex assembly, MCU subcellular localization, or resting mitochondrial membrane potential, indicating MCUR1 promotes MCU activity without being required for MCU complex assembly or stability. Patient fibroblasts and muscle biopsy analysis, mitochondrial Ca2+ uptake assays, autophagy flux assays, Western blot for MCU complex components, histological analysis, mitochondrial membrane potential measurement Acta neuropathologica communications Medium 42087238
2025 MCUR1 and its paralog CCDC90B form a hetero-oligomeric complex whose stability depends on MCUR1. Loss of MCUR1 exerts a dominant-negative effect on CCDC90B. Deletion of MCUR1/CCDC90B homologs in S. pombe (which lacks MCU) impairs lipid and amino acid metabolism; this is rescued by human MCUR1 expression, indicating a Ca2+-independent scaffold function. MCUR1 deficiency in patient fibroblasts upregulates autophagy, perturbs non-essential amino acid metabolism, and limits biosynthetic capacity. Complex stability assays (co-IP, protein abundance measurement), S. pombe genetic deletion with metabolic rescue by human MCUR1 expression, patient serum metabolomics, patient fibroblast functional assays (autophagy, amino acid metabolism, proliferation, migration) bioRxivpreprint Medium bio_10.1101_2025.10.14.682030

Source papers

Stage 0 corpus · 13 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 MCUR1 is an essential component of mitochondrial Ca2+ uptake that regulates cellular metabolism. Nature cell biology 447 23178883
2016 MCUR1 Is a Scaffold Factor for the MCU Complex Function and Promotes Mitochondrial Bioenergetics. Cell reports 184 27184846
2019 MCUR1 facilitates epithelial-mesenchymal transition and metastasis via the mitochondrial calcium dependent ROS/Nrf2/Notch pathway in hepatocellular carcinoma. Journal of experimental & clinical cancer research : CR 128 30909929
2015 CCDC90A (MCUR1) is a cytochrome c oxidase assembly factor and not a regulator of the mitochondrial calcium uniporter. Cell metabolism 105 25565209
2016 Mitochondrial calcium uniporter regulator 1 (MCUR1) regulates the calcium threshold for the mitochondrial permeability transition. Proceedings of the National Academy of Sciences of the United States of America 87 26976564
2017 MCUR1-Mediated Mitochondrial Calcium Signaling Facilitates Cell Survival of Hepatocellular Carcinoma via Reactive Oxygen Species-Dependent P53 Degradation. Antioxidants & redox signaling 62 28938844
2020 Yeast homologs of human MCUR1 regulate mitochondrial proline metabolism. Nature communications 24 32978391
2019 Characterization of MCU-Binding Proteins MCUR1 and CCDC90B - Representatives of a Protein Family Conserved in Prokaryotes and Eukaryotic Organelles. Structure (London, England : 1993) 20 30612859
2023 Mitochondrial Calcium Uniporter Regulator 1 (MCUR1) Relieves Mitochondrial Damage Induced by Lipopolysaccharide by Mediating Mitochondrial Ca2+ Homeostasis in Bovine Mammary Epithelial Cells. Journal of agricultural and food chemistry 6 37145034
2021 Key Role of MCUR1 in Malignant Progression of Breast Cancer. OncoTargets and therapy 6 34285508
2025 A highland-adaptation variant near MCUR1 reduces its transcription and attenuates erythrogenesis in Tibetans. Cell genomics 4 40043709
2023 miR‑4732‑5p promotes ovarian cancer mobility by targeting MCUR1. Oncology letters 3 37153048
2026 Biallelic MCUR1 nonsense mutation associated with vacuolar myopathy and altered mitochondrial calcium signaling. Acta neuropathologica communications 0 42087238

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