Affinage

MRPL20

Large ribosomal subunit protein bL20m · UniProt Q9BYC9

Length
149 aa
Mass
17.4 kDa
Annotated
2026-06-10
8 papers in source corpus 2 papers cited in narrative 2 extracted findings
Cross-family judge faithfulness: 1/1 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MRPL20 is a structural protein of the mitochondrial large ribosomal subunit required for mitochondrial translation and genome maintenance, established through its essential yeast ortholog YmL20, whose disruption causes mitochondrial dysfunction and mitochondrial DNA instability (PMID:2183197). Its mitochondrial import depends on OXA1L: under copper stress, OXA1L levels fall, MRPL20 import is disrupted, and oxidative phosphorylation complex I synthesis is impaired; mislocalized MRPL20 translocates to the nucleus and triggers the mitochondrial unfolded protein response as an adaptive response during early cuproptosis [PMID:bio_10.1101_2025.07.01.662679]. Beyond these findings, the structural role of MRPL20 within the assembled ribosome and the mechanism of its nuclear signaling are not characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 2 steps
  1. 1990 Medium

    Established that MRPL20's ortholog encodes a large-subunit mitochondrial ribosomal protein essential for mitochondrial function, linking it for the first time to maintenance of the mitochondrial genome.

    Evidence Gene cloning, sequencing, and disruption of the yeast ortholog YmL20 with phenotypic analysis

    PMID:2183197

    Open questions at the time
    • Human MRPL20 function inferred only from yeast ortholog
    • Direct demonstration of incorporation into the ribosome not shown
    • Mechanism connecting loss to mtDNA instability unresolved
  2. 2025 Medium

    Connected MRPL20 to copper stress biology by showing its mitochondrial import depends on OXA1L and that mislocalization drives a nuclear UPRmt signal, defining a stress-responsive role beyond constitutive ribosome function.

    Evidence Spatio-temporal mass spectrometry, genetic functional screen, and subcellular fractionation in a copper-stress/cuproptosis model (preprint)

    PMID:bio_10.1101_2025.07.01.662679

    Open questions at the time
    • Preprint, not peer-reviewed or independently replicated
    • Mechanism by which nuclear MRPL20 triggers UPRmt not defined
    • Direct OXA1L–MRPL20 interaction during import not demonstrated

Open questions

Synthesis pass · forward-looking unresolved questions
  • How MRPL20 is positioned within the assembled mitochondrial large ribosomal subunit and how its nuclear translocation is sensed to activate the UPRmt remain open.
  • No structural model of MRPL20 within the ribosome in the corpus
  • Signaling effectors downstream of nuclear MRPL20 unknown
  • Human-specific phenotypes of MRPL20 loss not characterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 1
Localization
GO:0005739 mitochondrion 2 GO:0005634 nucleus 1 GO:0005840 ribosome 1
Pathway
R-HSA-8953854 Metabolism of RNA 1 R-HSA-8953897 Cellular responses to stimuli 1
Partners
OXA1L
Complex memberships
mitochondrial large ribosomal subunit

Evidence

Reading pass · 2 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1990 MRP-L20 (yeast ortholog of MRPL20) encodes a 22.3-kDa mitochondrial ribosomal large subunit protein with an N-terminal presequence of 18 amino acids. Gene disruption experiments showed that the YmL20 protein is essential for mitochondrial function, and its absence causes instability of mitochondrial DNA. Gene cloning, sequencing, Southern blot hybridization, gene disruption experiments Nucleic acids research Medium 2183197
2025 Copper stress reduces OXA1L levels in mitochondria, which disrupts MRPL20 import into mitochondria and impairs oxidative phosphorylation complex I synthesis. This mitochondrial dysfunction promotes MRPL20 nuclear translocation, which triggers the mitochondrial unfolded protein response (UPRmt) as an adaptive mechanism to restore mitochondrial proteostasis during early cuproptosis. Spatio-temporal mass spectrometry (STMS) of subcellular proteome dynamics, genetic functional screen, subcellular fractionation/localization tracking bioRxivpreprint Medium bio_10.1101_2025.07.01.662679

Source papers

Stage 0 corpus · 8 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 Concurrent gene signatures for han chinese breast cancers. PloS one 67 24098497
1990 Cloning and characterization of nuclear genes for two mitochondrial ribosomal proteins in Saccharomyces cerevisiae. Nucleic acids research 40 2183197
1994 The complete sequence of an 18,002 bp segment of Saccharomyces cerevisiae chromosome XI contains the HBS1, MRP-L20 and PRP16 genes, and six new open reading frames. Yeast (Chichester, England) 12 8203164
2022 The lncRNA MRPL20-AS1 is associated with severe OSAS and downregulated upon hypoxic injury of endothelial cells. International journal of cardiology 10 35988669
2023 Integrated genomic analysis defines molecular subgroups in dilated cardiomyopathy and identifies novel biomarkers based on machine learning methods. Frontiers in genetics 2 36824437
2024 The impact of hsa-miR-1972 on the expression of von Willebrand factor in breast cancer progression regulation. PeerJ 1 39529627
2026 Interplay of the nasal microbiome and epigenome among adolescents. Clinical epigenetics 0 41749276
1992 Mapping the putative RNA helicase genes by sequence overlapping. Yeast (Chichester, England) 0 1481572

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