Affinage

POP5

Ribonuclease P/MRP protein subunit POP5 · UniProt Q969H6

Length
163 aa
Mass
18.8 kDa
Annotated
2026-06-10
35 papers in source corpus 18 papers cited in narrative 18 extracted findings
Cross-family judge vs UniProt: tie faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

POP5 is a universally conserved protein subunit of the RNase P and RNase MRP ribonucleoprotein endonucleases, where it functions as a catalytic activator of the RNA subunit (PMID:11413139, PMID:18558617). The protein adopts an RRM-like alpha-beta sandwich fold structurally homologous to the bacterial RNase P protein subunit and pairs with RPP30 (Rpp30/Rpp1) to reconstitute activity of the catalytic (C) domain of the RNase P RNA (PMID:16418270, PMID:20139629). The POP5•RPP30 binary complex is solely responsible for enhancing the RNA's rate of pre-tRNA cleavage (~60–100-fold in single-turnover kinetics) and for reducing the ionic requirement for catalysis, whereas the partner RPP21•RPP29 pair instead increases substrate affinity (PMID:18558617, PMID:20705647). POP5•RPP30 acts by recognizing a phylogenetically conserved catalytic core shared with bacterial and organellar RNase P RNAs, normalizing cleavage rates of consensus and non-consensus pre-tRNAs and selectively favoring correct over miscleavage (PMID:20705647, PMID:22298511, PMID:41889098). Structurally, POP5 and RPP30 assemble as a heterotetramer [RPP30-(POP5)2-RPP30] in solution that engages the RNA at 1:1 stoichiometry, with the C-terminal helix α4 of POP5 serving as the molecular recognition element for the RNA and RPP30 chaperoning POP5 into its active conformation by shielding its hydrophobic surfaces (PMID:22162665, PMID:26152732, PMID:25704799). In RNase MRP, the homologous Pop5•Rpp1 heterodimer binds the conserved catalytic-domain region of MRP RNA at a site corresponding to the bacterial protein-binding site (PMID:21878546). In human cells POP5 also promotes telomere lengthening, with a GWAS-linked locus regulating telomere length through transcriptional control of POP5 expression (PMID:38789417).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2001 High

    Established that human POP5 is a bona fide shared subunit of both RNase P and RNase MRP, placing it physically within nucleolar RNA-processing machinery rather than as a standalone factor.

    Evidence Co-immunoprecipitation, immunolocalization, and RNase P activity assays in HeLa cells with deletion mutants

    PMID:11413139

    Open questions at the time
    • Did not resolve which RNA domain POP5 contacts
    • Function of the conserved acidic C-terminal tail left undefined despite being dispensable for assembly
  2. 2006 High

    Determined the fold and direct binding partner of POP5, showing it is an RRM-like protein that pairs with RPP30 to reconstitute the catalytic domain of RNase P RNA.

    Evidence X-ray crystallography, NMR, and NMR chemical shift perturbation mapping of archaeal Pfu Pop5-RPP30

    PMID:16418270

    Open questions at the time
    • Kinetic contribution of POP5•RPP30 to catalysis not quantified
    • RNA contact residues not mapped
  3. 2008 High

    Defined the division of labor among RNase P protein pairs, demonstrating that POP5•RPP30 specifically accelerates catalysis (~100-fold) while RPP21•RPP29 does not affect rate.

    Evidence In vitro single-turnover kinetics with a pre-tRNA-RPR conjugate and binary complex addition in archaeal RNase P

    PMID:18558617

    Open questions at the time
    • Did not pinpoint the structural basis of rate enhancement
    • Mechanism of reduced ionic requirement unresolved
  4. 2010 High

    Resolved the functional partitioning further (POP5•RPP30 = rate; RPP21•RPP29 = affinity), established cross-species functional overlap with the bacterial RNase P protein, and identified an auxiliary L7Ae-dependent activation requiring RNA kink-turns.

    Evidence In vitro reconstitution with homologous/heterologous assemblies, single-turnover kinetics, chimeric domain-swap RNAs, and K-turn/L7Ae mutagenesis across multiple archaea

    PMID:20139629 PMID:20675586 PMID:20705647

    Open questions at the time
    • Atomic-level contacts of POP5 with the conserved catalytic core not visualized
    • Relationship between L7Ae stimulation and POP5 activity not fully integrated
  5. 2011 Medium

    Extended the model to eukaryotic complexes by showing the Pop5•Rpp1 heterodimer binds the MRP RNA catalytic-domain region, and mapped human POP5 binding to the H1 RNA catalytic domain.

    Evidence Protein-RNA binding assays and RNA binding-site mapping for RNase MRP; in vitro binding with recombinant proteins and nuclease footprinting for human H1 RNA

    PMID:21450806 PMID:21878546

    Open questions at the time
    • Functional rate contribution of human POP5 not separately quantified
    • In human RNase P, Rpp21•Rpp29 alone reconstituted endonucleolytic activity, leaving POP5's catalytic role in the human enzyme less defined
  6. 2014 Medium

    Characterized the assembly state of POP5•RPP30, revealing a (POP5•RPP30)2 dimer-of-dimers in solution that adopts 1:1 protein:RNA stoichiometry upon RNA binding.

    Evidence Native mass spectrometry with surface-induced dissociation and ion-mobility MS; site-specific hydroxyl radical footprinting of L7Ae in the holoenzyme

    PMID:25195671 PMID:25361963

    Open questions at the time
    • Functional significance of the solution dimer-of-dimers versus RNA-bound state unclear
    • Single technique for stoichiometry determination
  7. 2015 Medium

    Identified the molecular recognition element (POP5 helix α4) for the RNA stem-loop and a chaperone role for RPP30, and confirmed structural conservation of the heterotetramer across archaeal species.

    Evidence SPR binding, gel filtration, mutagenesis of PhoPop5; crystal structures of TkoRpp30 alone and the TkoRpp30-TkoPop5 complex with reconstitution assays

    PMID:25704799 PMID:26152732

    Open questions at the time
    • No structure of the POP5•RPP30 complex bound to RNA
    • How RPP30's TIM-barrel surface chaperones POP5 not visualized at atomic resolution
  8. 2022 Medium

    Showed the holoenzyme is robust to loss of canonical L7Ae-RNA kink-turn contacts due to redundant protein-protein interactions, including L7Ae contacts with POP5.

    Evidence Native mass spectrometry, mass photometry, kink-turn mutagenesis, and activity assays in archaeal RNase P

    PMID:35848927

    Open questions at the time
    • Direct L7Ae-POP5 interface not mapped structurally
    • Functional consequence of this redundancy in eukaryotic enzymes unknown
  9. 2024 Medium

    Linked POP5 to a cellular phenotype beyond RNA processing, demonstrating that POP5 expression levels control telomere length in human cells.

    Evidence POP5 overexpression and CRISPR/Cas9 deletion of a GWAS regulatory region with telomere length measurement in human/K562 cells

    PMID:38789417

    Open questions at the time
    • Biochemical mechanism connecting POP5 to telomere lengthening not dissected
    • Whether the telomere effect is through RNase P/MRP function is unresolved
  10. 2026 Medium

    Reinforced the deep functional analogy between POP5 and the bacterial RNase P protein, showing both activate the human C-domain RNA at low Mg2+ by recognizing shared core elements.

    Evidence In vitro reconstitution with H1 RNA variants and heterologous bacterial RnpA, Pb2+-probing, and UV melting

    PMID:41889098

    Open questions at the time
    • Novel finding not yet independently replicated
    • Structural basis of the conserved C-domain recognition not directly resolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • The biochemical mechanism by which POP5 expression promotes telomere lengthening in human cells, and whether this depends on its RNase P/MRP activity, remains undefined.
  • No molecular link established between POP5's catalytic-activator role and telomere maintenance
  • No structure of a human POP5-containing complex bound to substrate

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 5 GO:0098772 molecular function regulator activity 3 GO:0140098 catalytic activity, acting on RNA 3
Localization
GO:0005634 nucleus 1 GO:0005730 nucleolus 1
Pathway
R-HSA-8953854 Metabolism of RNA 3
Partners
RPP30
Complex memberships
RNase MRPRNase P

Evidence

Reading pass · 18 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 Human POP5 (hPop5) is a protein subunit of both RNase MRP and RNase P complexes; anti-hPop5 antibodies co-immunoprecipitate catalytically active RNase P from HeLa cells, and hPop5 localizes to the nucleus with accumulation in the nucleolus consistent with its RNase MRP/RNase P association. The conserved acidic C-terminal tail is not required for complex formation or RNase P activity. Co-immunoprecipitation with anti-hPop5 antibodies, immunofluorescence/immunolocalization, RNase P activity assay with partially purified complex, deletion mutant analysis The Journal of biological chemistry High 11413139
2006 Archaeal POP5 (Pfu Pop5) adopts an alpha-beta sandwich fold homologous to the RNA recognition motif (RRM) domain and is structurally similar to the bacterial RNase P protein subunit. NMR chemical shift mapping demonstrated that Pop5 interacts directly with RPP30 (Rpp30). Pop5 pairs with RPP30 to functionally reconstitute the catalytic domain of the RNase P RNA subunit. NMR spectroscopy, X-ray crystallography, NMR chemical shift perturbation mapping of Pop5-RPP30 interaction Proceedings of the National Academy of Sciences of the United States of America High 16418270
2008 In archaeal (Methanocaldococcus jannaschii) RNase P, the POP5-RPP30 binary complex enhances the RPR's rate of precursor tRNA self-cleavage by ~100-fold, while RPP21-RPP29 had no effect on rate; both binary complexes significantly reduced the monovalent and divalent ionic requirement for catalysis. In vitro reconstitution with pre-tRNA-RPR conjugate, single-turnover kinetic assays, binary protein complex addition experiments Nucleic acids research High 18558617
2010 POP5•RPP30 binary complex is solely responsible for enhancing the RNase P RNA's rate of precursor tRNA cleavage (by ~60-fold in single-turnover kinetics), while RPP21•RPP29 contributes to increased substrate affinity (~16-fold). POP5•RPP30 reconstituted with bacterial and organellar RNase P RNAs, indicating functional overlap with the bacterial RNase P protein and shared recognition of the phylogenetically conserved catalytic core. In vitro reconstitution with homologous/heterologous RPP assemblies, single-turnover kinetics, deletion mutagenesis of RPR Nucleic acids research High 20705647
2010 In Methanococcus maripaludis RNase P, addition of ribosomal protein L7Ae to a complex reconstituted with POP5, RPP21, RPP29, and RPP30 increases k(cat)/K(m) for pre-tRNA cleavage by ~360-fold. This effect requires both the conserved kink-turn nucleotides in the RNase P RNA and key amino acids in L7Ae known to be essential for K-turn binding. In vitro reconstitution, pre-tRNA cleavage kinetic assays, site-directed mutagenesis of RNA K-turn and L7Ae amino acids Proceedings of the National Academy of Sciences of the United States of America High 20675586
2010 Archaeal PhoPop5 (P. horikoshii) and PhoRpp30 function equivalently to the bacterial C5 protein in activating the C-domain of RNase P RNA, while PhoRpp21 and PhoRpp29 are implicated in stabilization of the S-domain, as demonstrated using chimeric RNAs exchanging C- and S-domains between M1 RNA and PhopRNA. Chimeric RNA domain-swap reconstitution assays, pre-tRNA cleavage activity measurements Bioscience, biotechnology, and biochemistry Medium 20139629
2011 Pop5 and Rpp1 (the yeast/human RNase MRP homologues of archaeal Pop5 and Rpp30) form a heterodimer that binds directly to the conserved area of the putative catalytic domain of RNase MRP RNA, at a site corresponding to the protein-binding site in bacterial RNase P RNA. Protein-RNA binding assay, identification of heterodimer formation, mapping of RNA binding site RNA (New York, N.Y.) Medium 21878546
2011 Five human RNase P protein subunits (Rpp20, Rpp21, Rpp25, Rpp29, and Pop5) bind to H1 RNA in vitro. Nuclease footprinting established that Pop5 (along with Rpp21 and Rpp29) binds the catalytic domain of H1 RNA. Rpp21 and Rpp29 are sufficient to reconstitute endonucleolytic activity. In vitro RNA-protein binding assay with refolded recombinant proteins, nuclease footprinting analysis Nucleic acids research Medium 21450806
2011 The POP5-RPP30 complex from Pyrococcus furiosus exists as a 78 kDa heterotetramer (two copies each of Pop5 and RPP30) in solution, with a net 1:1 stoichiometry by ITC. NMR chemical shift perturbations identified the binding surface of Pop5 on RPP30. NMR spectroscopy (backbone assignments and chemical shift perturbations), isothermal titration calorimetry (ITC), light scattering, size exclusion chromatography Archaea (Vancouver, B.C.) High 22162665
2012 POP5•RPP30 and RPP21•RPP29 independently rescue the RNase P RNA's mis-cleavage tendency by 4-fold each, and together by 25-fold, by selectively increasing the rate of correct cleavage (~11,140-fold) compared to mis-cleavage (~480-fold). This demonstrates that POP5•RPP30 functions to normalize cleavage rates of non-consensus and consensus pre-tRNAs, similar to the bacterial RNase P protein. In vitro single-turnover kinetic assays with cis-cleavage pre-tRNA conjugate, reconstitution with individual RPP pairs Nucleic acids research High 22298511
2013 In archaeal Pop5 (PhoPop5 from P. horikoshii), the C-terminal helices α4 and α5 (extra-structural elements beyond the core RRM fold) are required for pre-tRNA cleavage activity and for RNA annealing and strand displacement activities. Basic residues in α4 interact with the RNase P RNA, while hydrophobic residues in α4 stabilize the helix orientation against the β-sheet. Deletion of the α1-α2 loop did not affect annealing/strand displacement activity. Site-directed mutagenesis (deletion mutants), RNase P reconstitution assay (pre-tRNA cleavage), FRET-based RNA annealing and strand displacement assays Biochemical and biophysical research communications Medium 24120499
2014 Native mass spectrometry of Pyrococcus furiosus RNase P revealed that POP5•RPP30 forms a (POP5•RPP30)2 dimer-of-dimers complex in solution, but when bound to the RNA subunit (with or without RPP21•RPP29), the stoichiometry is 1:1 for all protein subunits relative to the RNA. Surface-induced dissociation (SID) coupled with ion mobility mass spectrometry (IM-MS), native mass spectrometry Angewandte Chemie (International ed. in English) Medium 25195671
2014 L7Ae binds to two kink-turn motifs in the Pyrococcus furiosus RNase P RNA, one in the catalytic domain and one in the specificity domain, as mapped by site-specific hydroxyl radical footprinting using single-Cys L7Ae-EDTA-Fe derivatives in a complex assembled with POP5, RPP21, RPP29, RPP30, and L7Ae. Site-specific hydroxyl radical footprinting (EDTA-Fe tethered to single-Cys L7Ae mutants) on fully reconstituted archaeal RNase P holoenzyme Nucleic acids research Medium 25361963
2015 The PhoPop5-PhoRpp30 heterotetramer [PhoRpp30-(PhoPop5)2-PhoRpp30] binds specifically to the stem-loop SL3 of RNase P RNA (PhopRNA) as measured by SPR; the C-terminal helix α4 of PhoPop5 acts as the molecular recognition element for SL3. PhoRpp30 assists PhoPop5 in achieving a functionally active conformation by shielding hydrophobic surfaces of PhoPop5 that would otherwise lead to inappropriate oligomerization. Surface plasmon resonance (SPR), gel filtration chromatography, site-directed mutagenesis of PhoPop5 Journal of biochemistry Medium 26152732
2015 Crystal structures of Thermococcus kodakarensis TkoRpp30 alone and in complex with TkoPop5 show that TkoRpp30 adopts a TIM barrel fold and TkoPop5 adopts an RRM-like fold, both highly conserved with their P. horikoshii counterparts. Reconstitution experiments show TkoPop5 and TkoRpp30 are functionally interchangeable with the corresponding P. horikoshii proteins in pre-tRNA cleavage assays. X-ray crystallography (TkoRpp30 alone and TkoRpp30-TkoPop5 complex), RNase P reconstitution/activity assays Bioscience, biotechnology, and biochemistry High 25704799
2022 In Methanocaldococcus jannaschii RNase P, each holoenzyme monomer contains one copy each of POP5, RPP30, RPP21, RPP29, and up to two copies of L7Ae. Abolishing canonical L7Ae-RPR kink-turn interactions (by mutating all kink-turns) is not detrimental to RNase P assembly or function due to redundancy from protein-protein interactions between L7Ae and other RPPs including POP5. Native mass spectrometry, mass photometry, kink-turn mutagenesis in RPR, biochemical RNase P activity assays Nucleic acids research Medium 35848927
2024 Overexpression of POP5 in human cells lengthens telomeres. CRISPR/Cas9 deletion of the predicted causal GWAS region reduces POP5 expression in K562 blood cells, indicating the locus regulates telomere length through transcriptional control of POP5. Overexpression (gain-of-function), CRISPR/Cas9 deletion of regulatory region, telomere length measurement Nature communications Medium 38789417
2026 The bacterial RNase P protein (E. coli RnpA) and eukaryotic Pop5 both activate H1 RNA (human RNase P RNA C-domain) at low Mg2+ concentration, indicating that these structurally analogous proteins recognize C-domain core elements common to all RNase P RNAs. In vitro reconstitution with H1 RNA variants and heterologous bacterial RnpA protein, Pb2+-probing, UV melting Chembiochem : a European journal of chemical biology Medium 41889098

Source papers

Stage 0 corpus · 35 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2003 The enigma of ribonuclease P evolution. Trends in genetics : TIG 109 14550630
2009 Novel biomarkers for prostate cancer including noncoding transcripts. The American journal of pathology 103 19893039
2010 Ribosomal protein L7Ae is a subunit of archaeal RNase P. Proceedings of the National Academy of Sciences of the United States of America 63 20675586
2006 Inventory and analysis of the protein subunits of the ribonucleases P and MRP provides further evidence of homology between the yeast and human enzymes. Nucleic acids research 60 16998185
2019 Structure of ribosome-bound azole-modified peptide phazolicin rationalizes its species-specific mode of bacterial translation inhibition. Nature communications 50 31594941
2010 Dissecting functional cooperation among protein subunits in archaeal RNase P, a catalytic ribonucleoprotein complex. Nucleic acids research 45 20705647
2008 Studies on Methanocaldococcus jannaschii RNase P reveal insights into the roles of RNA and protein cofactors in RNase P catalysis. Nucleic acids research 43 18558617
2006 Structure of Pfu Pop5, an archaeal RNase P protein. Proceedings of the National Academy of Sciences of the United States of America 42 16418270
2001 hPop5, a protein subunit of the human RNase MRP and RNase P endoribonucleases. The Journal of biological chemistry 42 11413139
2009 Solution structure of an archaeal RNase P binary protein complex: formation of the 30-kDa complex between Pyrococcus furiosus RPP21 and RPP29 is accompanied by coupled protein folding and highlights critical features for protein-protein and protein-RNA interactions. Journal of molecular biology 34 19733182
2014 Uncovering the stoichiometry of Pyrococcus furiosus RNase P, a multi-subunit catalytic ribonucleoprotein complex, by surface-induced dissociation and ion mobility mass spectrometry. Angewandte Chemie (International ed. in English) 32 25195671
2010 Cleavage of model substrates by archaeal RNase P: role of protein cofactors in cleavage-site selection. Nucleic acids research 22 20935047
2020 Combination of Linkage Mapping, GWAS, and GP to Dissect the Genetic Basis of Common Rust Resistance in Tropical Maize Germplasm. International journal of molecular sciences 21 32899999
2008 Solution structure of Pyrococcus furiosus RPP21, a component of the archaeal RNase P holoenzyme, and interactions with its RPP29 protein partner. Biochemistry 19 18922021
2010 Archaeal homologs of human RNase P protein pairs Pop5 with Rpp30 and Rpp21 with Rpp29 work on distinct functional domains of the RNA subunit. Bioscience, biotechnology, and biochemistry 18 20139629
2011 RNA binding properties of conserved protein subunits of human RNase P. Nucleic acids research 17 21450806
2012 Fidelity of tRNA 5'-maturation: a possible basis for the functional dependence of archaeal and eukaryal RNase P on multiple protein cofactors. Nucleic acids research 15 22298511
2014 The L7Ae protein binds to two kink-turns in the Pyrococcus furiosus RNase P RNA. Nucleic acids research 14 25361963
2003 Using ancestral sequences to uncover potential gene homologues. Applied bioinformatics 14 15130821
2011 Cooperative RNP assembly: complementary rescue of structural defects by protein and RNA subunits of archaeal RNase P. Journal of molecular biology 11 21683084
2012 Thermodynamics of coupled folding in the interaction of archaeal RNase P proteins RPP21 and RPP29. Biochemistry 9 22243443
2023 Dual-Uptake Mode of the Antibiotic Phazolicin Prevents Resistance Acquisition by Gram-Negative Bacteria. mBio 8 36802165
2022 Elucidation of structure-function relationships in Methanocaldococcus jannaschii RNase P, a multi-subunit catalytic ribonucleoprotein. Nucleic acids research 8 35848927
2011 Interactions of a Pop5/Rpp1 heterodimer with the catalytic domain of RNase MRP. RNA (New York, N.Y.) 8 21878546
2024 Validation of human telomere length multi-ancestry meta-analysis association signals identifies POP5 and KBTBD6 as human telomere length regulation genes. Nature communications 7 38789417
2013 Extra-structural elements in the RNA recognition motif in archaeal Pop5 play a crucial role in the activation of RNase P RNA from Pyrococcus horikoshii OT3. Biochemical and biophysical research communications 7 24120499
2011 Assembly of the complex between archaeal RNase P proteins RPP30 and Pop5. Archaea (Vancouver, B.C.) 7 22162665
2015 Conservation and population genetic diversity of Curcuma wenyujin (Zingiberaceae), a multifunctional medicinal herb. Genetics and molecular research : GMR 6 26400273
2007 Transcriptional linkage of Haloferax volcanii proteasomal genes with non-proteasomal gene neighbours including RNase P, MOSC domain and SAM-methyltransferase homologues. Microbiology (Reading, England) 6 17768244
2015 Functional implication of archaeal homologues of human RNase P protein pair Pop5 and Rpp30. Journal of biochemistry 5 26152732
2015 On archaeal homologs of the human RNase P proteins Pop5 and Rpp30 in the hyperthermophilic archaeon Thermococcus kodakarensis. Bioscience, biotechnology, and biochemistry 4 25704799
2024 miR-571 manipulating termite immune response to fungus and showing potential for green management of Copotermes formosanus (Blattodea: Isoptera). Pesticide biochemistry and physiology 3 40015866
2025 Ribonuclease P/MRP subunit RPP40 coordinates the transcription of pre-rRNA and ribosomal protein genes to promote Hepatocellular carcinoma malignancy. Gene 1 40517827
2026 Resurrecting the Activity of the RNA Subunit of Human RNase P. Chembiochem : a European journal of chemical biology 0 41889098
2014 Genetic diversity and population structure of black Dahe pig based on DNA sequences analyses of mitochondrial and nuclear genes. Mitochondrial DNA. Part A, DNA mapping, sequencing, and analysis 0 24617464

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