Affinage

RPS28

Small ribosomal subunit protein eS28 · UniProt P62857

Length
69 aa
Mass
7.8 kDa
Annotated
2026-06-10
23 papers in source corpus 10 papers cited in narrative 10 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

RPS28 is a small, eukaryote-specific structural protein of the 40S ribosomal subunit head that contributes to translational accuracy and selective mRNA translation (PMID:947902, PMID:7498767). It binds with high affinity to the 3' major domain of 18S rRNA and localizes to the head of the 40S subunit, where it sits near the decoding center (PMID:20951136). Genetic and in vitro translation analyses in yeast established RPS28 as a regulator of translational fidelity that acts in functional concert with ribosomal protein S4/SUP44, with Lys-62 being a critical residue whose substitution shifts decoding accuracy and antibiotic sensitivity (PMID:7498767, PMID:8950190). RPS28 levels are tuned post-transcriptionally: a tRNA-derived fragment, LeuCAG3'tsRNA, binds the RPS28 mRNA coding sequence and 3' UTR and enhances its translation at a post-initiation step (PMID:31851915), while in yeast an Edc3-bound autoregulatory feedback loop directs RPS28B mRNA decay through direct binding to the Rps28 core (PMID:23956223). Incorporation of RPS28 into ribosomes, downstream of FBL-catalyzed rRNA 2'-O-methylation, enables selective translation of a defined protein subset including oncogenes such as MTA1, IRAK1, and TMSB10, indicating a specialized-ribosome function (PMID:41260515). De novo mutations affecting the RPS28 start codon cause Diamond-Blackfan anemia with mandibulofacial dysostosis (PMID:24942156).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1976 Medium

    Establishing whether S28 was a genuine ribosomal constituent was the first requirement; purification from native 40S subunits defined it as a structural small-subunit protein.

    Evidence Protein purification and amino acid composition analysis from rat liver 40S subunits

    PMID:947902

    Open questions at the time
    • No sequence or gene identity
    • No functional role assigned
    • Position within the subunit unknown
  2. 1991 Medium

    Defining the primary structure and gene copy number converted the purified protein into a molecularly tractable entity and tied it to a yeast ortholog.

    Evidence cDNA sequencing and genomic Southern blot in rat, with homology to S. cerevisiae S33

    PMID:1679328

    Open questions at the time
    • No functional consequence of sequence features
    • rRNA contacts unknown
    • No structural model
  3. 1996 High

    Whether RPS28 actively shapes decoding rather than merely scaffolding was answered by showing that specific substitutions, notably at Lys-62, bidirectionally alter translational accuracy and that RPS28 acts with S4/SUP44.

    Evidence Yeast genetic suppressor and antibiotic assays plus poly(U)-directed cell-free translation with mutant ribosomes

    PMID:7498767 PMID:8950190

    Open questions at the time
    • Structural basis of Lys-62 effect on the decoding center not resolved
    • Mechanism of functional coupling to S4 unknown
    • Conservation of effect in mammalian ribosomes not tested
  4. 2010 High

    Localizing RPS28 and defining its rRNA target established the physical basis for its decoding-center role in the human ribosome.

    Evidence RNase H cleavage and mass spectrometry of human 40S plus quantitative in vitro binding of recombinant S28e to the 3' major domain of 18S rRNA

    PMID:20951136

    Open questions at the time
    • Atomic-resolution contacts not defined
    • Assembly order into the subunit unknown
    • Link between binding site and fidelity not directly tested
  5. 2013 High

    How RPS28 abundance is homeostatically controlled was partly answered by identifying a direct Edc3-Rps28 interaction driving an autoregulatory mRNA decay loop in yeast.

    Evidence In vitro direct binding and functional analysis of Edc3 motif mutants with RPS28B mRNA decay assays

    PMID:23956223

    Open questions at the time
    • Whether an equivalent autoregulatory loop exists in mammals unknown
    • Structural detail of the Edc3-binding motif on Rps28 not resolved
    • Trigger sensing excess Rps28 not defined
  6. 2014 Medium

    Linking RPS28 to human disease, start-codon mutations were identified as a cause of Diamond-Blackfan anemia with craniofacial anomalies, implicating defective ribosome function in erythropoiesis and development.

    Evidence Whole-exome and Sanger sequencing of two unrelated DBA probands with mandibulofacial dysostosis

    PMID:24942156

    Open questions at the time
    • No functional rescue or molecular mechanism experiment
    • Tissue-specific basis of erythroid sensitivity unexplained
    • Quantitative effect on RPS28 protein not measured
  7. 2019 High

    A post-transcriptional regulator of RPS28 in mammals was identified, showing a tRNA-derived small RNA enhances RPS28 mRNA translation at a post-initiation step via structural remodeling.

    Evidence RNA structure probing, reporter assays, ribosome profiling, binding-site mutagenesis, and cross-species validation in mouse

    PMID:31851915

    Open questions at the time
    • Mechanism of post-initiation enhancement at the ribosome unresolved
    • Physiological contexts engaging this regulation unclear
    • Protein machinery mediating tsRNA action not identified
  8. 2021 Medium

    Whether RPS28 could confer ribosome specialization was supported by showing muscle-specific RpS28a overexpression selectively reshapes the proteome and reduces early mortality in Drosophila.

    Evidence Tissue-specific transgenic overexpression with proteomics and lifespan analysis in Drosophila

    PMID:33974070

    Open questions at the time
    • Molecular basis of selective translation not defined
    • Relevance to mammalian tissues untested
    • Overexpression rather than physiological-level effect
  9. 2025 Medium

    Connecting RPS28 incorporation to rRNA modification and oncogenic translation showed that FBL-dependent 2'-O-methylation controls RPS28 loading into ribosomes, which is required for selective translation of specific oncogenes.

    Evidence siRNA knockdown, RiboMethSeq, SHAPE, ribosome fractionation, and translation efficiency in triple-negative breast cancer cells

    PMID:41260515

    Open questions at the time
    • How methylation regulates RPS28 incorporation mechanistically unresolved
    • Generality beyond TNBC unknown
    • Direct demonstration of selective decoding by RPS28-containing ribosomes lacking

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unknown how RPS28's rRNA-binding position and Lys-62 chemistry mechanistically govern decoding-center fidelity and how this links to its emerging role in specialized, selective translation.
  • No atomic-resolution model coupling RPS28 contacts to decoding accuracy
  • No unified mechanism connecting fidelity control to oncogene-selective translation
  • Mammalian autoregulation of RPS28 abundance uncharacterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0045182 translation regulator activity 3 GO:0005198 structural molecule activity 2 GO:0003723 RNA binding 1
Localization
GO:0005840 ribosome 2
Pathway
R-HSA-392499 Metabolism of proteins 4 R-HSA-1643685 Disease 2 R-HSA-8953854 Metabolism of RNA 1
Partners
EDC3FBLRPS4/SUP44
Complex memberships
40S ribosomal subunit

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1976 RPS28 (S28) was isolated and purified from rat liver 40S ribosomal subunit by ion-exchange chromatography and gel filtration; its molecular weight and amino acid composition were characterized, establishing it as a structural component of the small ribosomal subunit. Protein purification (ion-exchange chromatography, gel filtration), SDS-PAGE, amino acid composition analysis The Journal of biological chemistry Medium 947902
1991 The primary amino acid sequence of rat ribosomal protein S28 (RPS28) was determined: 69 amino acids, molecular weight 7,836 Da, encoded by 8–10 gene copies, with an mRNA of ~450 nucleotides; rat S28 is homologous to Saccharomyces cerevisiae S33. cDNA sequencing, Southern blot hybridization, sequence homology analysis Biochemical and biophysical research communications Medium 1679328
1995 In yeast, different mutations in RPS28 (encoded by RPS28A and RPS28B) can have diametrically opposite effects on translational accuracy: substitutions in the diverged N-terminal portion cause nonsense suppression or antibiotic sensitivity, while substitutions in the conserved C-terminal portion counteract SUP44/SUP46-associated antibiotic sensitivity, establishing RPS28 as a regulator of translational fidelity at the decoding center. Site-directed and random mutagenesis, genetic suppressor analysis, antibiotic sensitivity assays Genetics High 7498767
1996 Using a poly(U)-dependent cell-free translation system with yeast ribosomes bearing RPS28 mutant proteins, specific substitutions at Lys-62 of S28 (Lys→Asn, Thr, or Gln) increased translational accuracy and antibiotic resistance, while Lys-62→Arg decreased accuracy. RPS28 and S4 (SUP44) interact functionally to control translational accuracy, and S28 mutations can partially reverse the translational infidelity caused by SUP44. In vitro cell-free translation system (poly(U)-directed), genetic epistasis with SUP44 alleles, antibiotic sensitivity assays, site-directed mutagenesis Biochimica et biophysica acta High 8950190
2010 RNase H site-specific cleavage of the human 40S ribosomal subunit and mass spectrometry of the resulting head fragment showed that eukaryote-specific RPS28 (S28e) localizes to the head of the 40S subunit. Recombinant S28e binds specifically to the 3' major domain of 18S rRNA with high affinity (Ka = 8.0±0.5×10⁹ M⁻¹). RNase H cleavage of 40S subunit, mass spectrometry, in vitro RNA-binding assay (Ka measurement) with recombinant protein FEBS letters High 20951136
2013 Yeast Edc3 protein directly and tightly binds to the globular core of Rps28 through a specific motif present only in Edc3 proteins from Saccharomycetaceae yeast. This Rps28-Edc3 interaction is exclusively required for the autoregulatory feedback loop controlling RPS28B mRNA decay but is dispensable for Edc3's general mRNA decay functions and YRA1 pre-mRNA decay regulation. Direct binding assay (in vitro), functional genetic analysis of Edc3 motif mutants, mRNA decay assays Nucleic acids research High 23956223
2014 De novo mutations affecting the RPS28 start codon (affecting translation initiation) were found in two unrelated probands with Diamond-Blackfan anemia combined with mandibulofacial dysostosis, identifying RPS28 as a novel DBA disease gene and implicating its loss in impaired ribosome biogenesis leading to defective erythropoiesis and abnormal development. Whole-exome sequencing, Sanger sequencing, clinical phenotyping American journal of medical genetics. Part A Medium 24942156
2019 The tRNA-derived small RNA LeuCAG3'tsRNA regulates RPS28 levels by binding to both the coding sequence (CDS) and 3' UTR of RPS28 mRNA, altering its secondary structure and enhancing translation at a post-initiation step. The functional 3' UTR target site is primate-specific while the CDS site is conserved across vertebrates, and this mechanism also operates in mouse Rps28. RNA secondary structure analysis, reporter assays, ribosome profiling, site-directed mutation of binding sites, species conservation analysis Cell reports High 31851915
2021 In Drosophila, muscle-specific overexpression of the RpS28a variant (at germline-like levels) promotes synthesis of a specific subset of proteins with anti-aging roles and decreases early mortality, demonstrating that RpS28 contributes to a specialized ribosome that selectively regulates the muscle proteome. Tissue-specific transgenic overexpression, proteomics (mass spectrometry), lifespan analysis G3 (Bethesda, Md.) Medium 33974070
2025 FBL (Fibrillarin) knockdown in triple-negative breast cancer cells reduces RPS28 incorporation into ribosomes (confirmed by altered 18S rRNA structure via SHAPE); silencing RPS28 independently impairs oncogenic traits and reduces translation of MTA1, IRAK1, and TMSB10, establishing that RPS28 incorporation into ribosomes is required for selective translation of oncogenes downstream of FBL-mediated rRNA 2'-O-methylation. siRNA knockdown, RiboMethSeq, SHAPE (RNA structure probing), ribosome fractionation, translation efficiency measurement Cancer letters Medium 41260515

Source papers

Stage 0 corpus · 23 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Histone code pathway involving H3 S28 phosphorylation and K27 acetylation activates transcription and antagonizes polycomb silencing. Proceedings of the National Academy of Sciences of the United States of America 139 21282660
2014 Diamond-Blackfan anemia with mandibulofacial dystostosis is heterogeneous, including the novel DBA genes TSR2 and RPS28. American journal of medical genetics. Part A 113 24942156
2019 A tRNA-Derived Small RNA Regulates Ribosomal Protein S28 Protein Levels after Translation Initiation in Humans and Mice. Cell reports 95 31851915
2005 MAP kinase-mediated phosphorylation of distinct pools of histone H3 at S10 or S28 via mitogen- and stress-activated kinase 1/2. Journal of cell science 88 15870105
1976 The isolation of eukaryotic ribosomal proteins. The purification and characterization of the 40 S ribosomal subunit proteins S2, S3, S4, S5, S6, S7, S8, S9, S13, S23/S24, S27, and S28. The Journal of biological chemistry 72 947902
1996 Mutations in yeast ribosomal proteins S28 and S4 affect the accuracy of translation and alter the sensitivity of the ribosomes to paromomycin. Biochimica et biophysica acta 46 8950190
1995 Alterations in ribosomal protein RPS28 can diversely affect translational accuracy in Saccharomyces cerevisiae. Genetics 26 7498767
1994 Processing of human prosomatostatin in AtT-20 cells: S-28 and S-14 are generated in different secretory pathways. Biochemical and biophysical research communications 26 7999027
2021 An age-downregulated ribosomal RpS28 protein variant regulates the muscle proteome. G3 (Bethesda, Md.) 18 33974070
2013 Identification of the Rps28 binding motif from yeast Edc3 involved in the autoregulatory feedback loop controlling RPS28B mRNA decay. Nucleic acids research 18 23956223
2000 Isolation and molecular characterisation of the gene encoding the cytoplasmic ribosomal protein S28 in Prunus persica [L.]] Batsch. Molecular & general genetics : MGG 15 10778738
2008 Pharmacological properties and discriminative stimulus effects of a novel and selective 5-HT2 receptor agonist AL-38022A [(S)-2-(8,9-dihydro-7H-pyrano[2,3-g]indazol-1-yl)-1-methylethylamine]. Pharmacology, biochemistry, and behavior 14 18718483
2003 The ribosomal small-subunit protein S28 gene from Helianthus annuus (Asteraceae) is down-regulated in response to drought, high salinity, and abscisic acid. American journal of botany 14 21659145
2021 Centromere protein U enhances the progression of bladder cancer by promoting mitochondrial ribosomal protein s28 expression. The Korean journal of physiology & pharmacology : official journal of the Korean Physiological Society and the Korean Society of Pharmacology 9 33602882
2005 A novel protease from Entamoeba histolytica homologous to members of the family S28 of serine proteases. Experimental parasitology 9 15955323
2010 Site-specific cleavage of the 40S ribosomal subunit reveals eukaryote-specific ribosomal protein S28 in the subunit head. FEBS letters 7 20951136
2023 In silico analysis of two Haemonchus spp. serine protease peptides (S28) and their immunomodulatory activity in vitro. Molecular and biochemical parasitology 5 36681328
2005 Variant of mitochondrial ribosomal protein s28 (mrps28) gene is differentially expressed in response to radiation in a cervical carcinoma derived cell line. Indian journal of biochemistry & biophysics 5 23923566
1991 Genetic characterization of esterase 28 (ES-28) of the house mouse. Biochemical genetics 4 1883319
1991 The primary structure of rat ribosomal protein S28. Biochemical and biophysical research communications 3 1679328
2025 Diagnosis and treatment of Diamond-Blackfan anemia and Pierre-Robin sequence caused by a novel mutation of RPS28 gene. Hematology (Amsterdam, Netherlands) 0 40135709
2025 Fibrillarin-dependent 2'-O-methylation modulates RPS28 ribosome incorporation and oncogenic translation. Cancer letters 0 41260515
2022 Characterization of two constitutive promoters RPS28 and EIF1 for studying soybean growth, development, and symbiotic nodule development. aBIOTECH 0 36312443

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