The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The requested target is Rrp36 encoded by rrp36 (systematic locus SPAC823.04) in Schizosaccharomyces pombe strain 972/ATCC 24843, UniProt Q9P6P2. The supplied annotations—“rRNA biogenesis protein Rrp36,” RRP36 family, InterPro IPR009292, and Pfam PF06102—are mutually consistent. However, the gene-specific literature is limited: the retrieved definitive study experimentally examined Saccharomyces cerevisiae Rrp36 and human RRP36, not Q9P6P2. Accordingly, the most defensible annotation of the fission-yeast protein is a strong orthology-based inference, rather than a direct experimental demonstration in S. pombe.
Rrp36 is best classified as a non-enzymatic nucleolar ribosome-assembly/pre-rRNA-processing factor. It is expected to join the early 90S preribosome or small-subunit (SSU) processome, facilitate early cleavages of the precursor rRNA, and thereby enable maturation of 18S rRNA and production of the 40S ribosomal subunit. No catalytic reaction, active site, or substrate-specific enzymatic activity has been demonstrated. Its functional substrate is better described as the nascent pre-rRNA–protein assembly, rather than a freely diffusible small molecule or an isolated RNA substrate. This interpretation follows the absence of recognizable catalytic motifs and the protein’s experimentally established preribosome association in orthologous systems. (gerus2010evolutionarilyconservedfunction pages 10-11, gerus2010evolutionarilyconservedfunction pages 4-7, gerus2010evolutionarilyconservedfunction pages 7-8)
The family assignment agrees with comparative work showing conserved Rrp36 sequence blocks across eukaryotes. That study found at least one Rrp36 homolog in every examined eukaryotic genome but none in bacteria or archaea; human RRP36 was 21% identical and 44% similar to budding-yeast Rrp36. No recognizable catalytic motif was found. (gerus2010evolutionarilyconservedfunction pages 10-11, gerus2010evolutionarilyconservedfunction pages 14-15)
Rrp36 must not be confused with HCA66/Utp6. The experimentally identified S. pombe HCA66 homolog is SpUtp6, encoded by SPBC244.02c, not SPAC823.04. SpUtp6-mCherry localized to the nucleolus and did not colocalize with the spindle-pole-body marker Cdc11-GFP. Those observations concern SpUtp6 and must not be assigned to Q9P6P2. (bonnart2012mammalianhca66protein pages 10-11, bonnart2012mammalianhca66protein pages 7-10)
| Annotation topic | Best-supported conclusion | Evidence system/method | Evidence status for Q9P6P2 | Confidence/caveat |
|---|---|---|---|---|
| Exact identity | rrp36 / SPAC823.04, encoding rRNA-biogenesis protein Rrp36 in Schizosaccharomyces pombe strain 972/ATCC 24843; UniProt Q9P6P2 | User-supplied UniProt record | Provided UniProt annotation | High for database identity; not independently demonstrated by the retrieved papers |
| Family and domain | Member of the eukaryotic RRP36 family, annotated with Pfam PF06102 and InterPro IPR009292 | User-supplied UniProt/domain annotations; comparative sequence analysis identifies conserved Rrp36 blocks but no recognizable catalytic motif (gerus2010evolutionarilyconservedfunction pages 10-11, gerus2010evolutionarilyconservedfunction pages 14-15) | Provided UniProt annotation, supported by orthology | High for family assignment; domain annotation does not establish a catalytic activity |
| Primary molecular role | Most plausibly a non-enzymatic pre-rRNA-processing and preribosome-assembly factor, rather than a nuclease or other enzyme | Budding-yeast depletion, preribosome purification, RNA analysis, and absence of recognizable catalytic motifs (gerus2010evolutionarilyconservedfunction pages 10-11, gerus2010evolutionarilyconservedfunction pages 7-8) | Orthology-based inference | Moderate-to-high; no catalytic reaction, active site, substrate-specificity assay, or direct biochemical activity has been reported for Q9P6P2 |
| Cellular localization | Predicted to function predominantly in the nucleolus, where early small-subunit ribosome assembly occurs | S. cerevisiae Rrp36–3HA colocalized with nucleolar GFP-Nop1; human EGFP-RRP36 colocalized with fibrillarin and was detected in purified nucleoli (gerus2010evolutionarilyconservedfunction pages 4-7, gerus2010evolutionarilyconservedfunction pages 8-10) | Orthology-based inference | High biological plausibility, but direct microscopy of Q9P6P2 was not found |
| Preribosome association | Expected to associate mainly with the 90S/SSU processome and more weakly with downstream pre-40S particles | Budding-yeast sucrose gradients, immunoprecipitation/TAP purification, Northern/primer-extension analysis, and mass spectrometry detected early pre-rRNAs, U3 snoRNA, and 90S/pre-40S factors (gerus2010evolutionarilyconservedfunction pages 4-7, gerus2010evolutionarilyconservedfunction pages 7-8) | Orthology-based inference | Moderate-to-high; direct Q9P6P2 interactome or particle-association data are lacking |
| Pre-rRNA cleavage function | Expected to support early cleavages corresponding to A0, A1, and A2 in the budding-yeast pathway | Conditional S. cerevisiae depletion caused 35S pre-rRNA accumulation and loss of 33S, 32S, 20S, and 27SA2 intermediates (gerus2010evolutionarilyconservedfunction pages 7-8) | Orthology-based inference | High for budding yeast; exact cleavage-site nomenclature and processing order should not be transferred uncritically to S. pombe without direct mapping |
| Ribosomal-subunit output | Expected to be required for efficient 18S rRNA maturation and 40S-subunit production | Budding-yeast depletion reduced free 40S and mature 18S; human knockdown impaired 18S production and reduced 21S and 18S-E precursors by about 60% and 40%, respectively (gerus2010evolutionarilyconservedfunction pages 11-13, gerus2010evolutionarilyconservedfunction pages 7-8) | Orthology-based inference | Strong conserved-system evidence, but no Q9P6P2 depletion or pulse-labeling study was found |
| Pathway specificity | Function is substantially more specific to the small-subunit pathway than to 60S maturation | Budding-yeast depletion left 5S, 5.8S, and 25S production unaffected; human depletion did not impair 28S or the tested 60S-pathway precursors (gerus2010evolutionarilyconservedfunction pages 11-13, gerus2010evolutionarilyconservedfunction pages 7-8) | Orthology-based inference | Moderate-to-high; secondary effects on global growth remain possible |
| Nuclear/nucleolar targeting | Conserved lysine/arginine-rich terminal sequence may act as a nuclear-localization signal | Comparative sequence analysis and computational NLS prediction (gerus2010evolutionarilyconservedfunction pages 10-11) | Orthology-based inference | Low-to-moderate; prediction has not been functionally tested for Q9P6P2 |
| Evolutionary conservation | Rrp36 is broadly conserved across examined eukaryotes, with no homolog identified in bacteria or archaea in the definitive comparative study | Cross-genome homology analysis; human RRP36 showed 21% identity and 44% similarity to budding-yeast Rrp36 (gerus2010evolutionarilyconservedfunction pages 14-15) | Orthology-based inference supporting family assignment | Moderate-to-high; conservation supports shared function but does not replace direct S. pombe validation |
| Direct S. pombe evidence | No retrieved primary study directly tested Q9P6P2/SPAC823.04 localization, depletion phenotype, pre-rRNA processing, physical interactions, essentiality, or biochemical activity | Targeted literature searches and inspection of the definitive Rrp36 study, which experimentally examined S. cerevisiae and human RRP36 rather than Q9P6P2 (gerus2010evolutionarilyconservedfunction pages 11-13, gerus2010evolutionarilyconservedfunction pages 14-15, gerus2010evolutionarilyconservedfunction pages 10-11) | Not established | Major annotation limitation; mechanistic conclusions for Q9P6P2 must be labeled as orthology-based |
| Recent research status | No 2023–2024 gene-specific experimental publication on S. pombe Q9P6P2 was identified; the principal mechanistic evidence remains the 2010 comparative study | Targeted searches for Q9P6P2, SPAC823.04, fission-yeast Rrp36, and recent structural/functional work | Not established | Absence from retrieved results is not proof that no study exists, but it precludes claiming a recent direct advance |
| Identity warning | SpUtp6/SPBC244.02c is the S. pombe homolog of mammalian HCA66 and is not Rrp36/SPAC823.04 | Sequence comparison and SpUtp6-mCherry localization in S. pombe identified SPBC244.02c as the HCA66-related protein (bonnart2012mammalianhca66protein pages 10-11, bonnart2012mammalianhca66protein pages 7-10) | Direct evidence for distinction from Q9P6P2 | High; HCA66/Utp6 findings must not be attributed to Rrp36 |
Table: Evidence-weighted annotation of fission-yeast Rrp36, explicitly separating the supplied UniProt identity from orthology-based functional inference and unresolved Q9P6P2-specific claims.
Rrp36 is most likely an assembly or processing-support factor in early 40S ribosome biogenesis, not an enzyme, transporter, receptor, or signaling protein. In budding yeast, tagged Rrp36 copurified with 35S/33S/32S, 23S, and 20S pre-rRNAs, U3 snoRNA, and proteins of 90S and pre-40S particles. Sucrose-gradient sedimentation, immunoprecipitation, TAP purification, Northern/primer-extension analyses, and mass spectrometry collectively placed it principally in 90S preribosomes and more weakly in pre-40S particles. (gerus2010evolutionarilyconservedfunction pages 4-7, gerus2010evolutionarilyconservedfunction pages 7-8)
No nuclease, helicase, ATPase, GTPase, transferase, or other catalytic activity has been reported for Rrp36. There is therefore no known catalyzed reaction or chemically defined substrate specificity. A more precise mechanistic formulation is that Rrp36 helps establish or stabilize a preribosomal state competent for early pre-rRNA cleavage. Whether it directly contacts pre-rRNA, recruits a catalytic processing factor, or stabilizes local RNA/protein architecture remains unresolved for Q9P6P2.
In budding yeast, Rrp36 recruitment depends on prior assembly of the UTP-A and UTP-B modules. Depleting Utp17 or Pwp2 lowered Rrp36 accumulation and altered its sedimentation, whereas Rrp5 depletion did not prevent recruitment. Conversely, Rrp36 depletion did not abolish incorporation of the tested UTP modules or U3, U14, and snR30 snoRNPs. This suggests that Rrp36 is not a foundational recruiter of the entire SSU processome; it acts after important early modules have loaded, promoting a subsequent processing-competent state. Preferential association with UTP-C was suggested, but the recruitment mechanism was not resolved. (gerus2010evolutionarilyconservedfunction pages 10-11, gerus2010evolutionarilyconservedfunction pages 13-14, gerus2010evolutionarilyconservedfunction pages 8-10)
For S. pombe, this assembly order should be treated as a mechanistic hypothesis based on conservation, not as directly mapped Q9P6P2 biology.
Rrp36 functions in the pathway:
nucleolar pre-rRNA transcription/assembly → 90S or SSU-processome maturation → early pre-rRNA cleavages → pre-40S formation → 18S-rRNA maturation → mature 40S ribosomal subunit.
In S. cerevisiae, conditional Rrp36 depletion caused accumulation of 35S pre-rRNA and loss of 33S, 32S, 20S, and 27SA2 intermediates, consistent with defects at the early A0, A1, and A2 cleavages. Free 40S subunits and mature 18S rRNA decreased, whereas the 60S peak increased relative to 40S. Production of 5S, 5.8S, and 25S rRNAs was not impaired, supporting preferential action in the small-subunit pathway. (gerus2010evolutionarilyconservedfunction pages 7-8)
The exact cleavage-site nomenclature and precursor topology differ among eukaryotes. Consequently, one should not assert without direct mapping that Q9P6P2 acts at identically named S. pombe sites. The conserved conclusion is narrower: Rrp36 promotes early processing events required to separate and mature the 18S-rRNA/40S branch.
Human experiments independently support that conclusion. Approximately 70% depletion of RRP36 mRNA left 45S precursor accumulation roughly unchanged, reduced 41S by about 40%, and produced approximately threefold accumulation of 30S pre-rRNA. In another analysis, 21S and 18S-E intermediates decreased by approximately 60% and 40%, respectively. Metabolic pulse labeling showed defective mature 18S synthesis, whereas 28S production and tested large-subunit precursors were unaffected. (gerus2010evolutionarilyconservedfunction pages 11-13, gerus2010evolutionarilyconservedfunction pages 10-11)
This cross-species selectivity is strong evidence that the ancestral RRP36-family function lies in 40S, rather than general 40S/60S, biogenesis.
The most likely site of Q9P6P2 function is the nucleolus within the nucleus, where early preribosome assembly and pre-rRNA processing occur. In budding yeast, Rrp36-3HA was nuclear and enriched in a nucleolar crescent overlapping the nucleolar marker GFP-Nop1. In HeLa cells, EGFP-RRP36 colocalized with fibrillarin, and endogenous RRP36 was detected by mass spectrometry in purified nucleoli. (gerus2010evolutionarilyconservedfunction pages 4-7, gerus2010evolutionarilyconservedfunction pages 8-10)
Comparative sequence analysis identified lysine/arginine-rich terminal regions predicted to serve as nuclear-localization signals. This supports nuclear import but remains a computational prediction rather than a demonstrated targeting sequence in Q9P6P2. (gerus2010evolutionarilyconservedfunction pages 10-11)
Thus, nucleolar localization is high-confidence by conserved-system inference, but direct fluorescence microscopy, fractionation, or proximity labeling of the native S. pombe protein was not found.
Conditional depletion in budding yeast made Rrp36 barely detectable within approximately one hour and rapidly caused a growth defect. Ribosome profiles showed reduced free 40S and a relative excess of free 60S, consistent with failure to generate balanced ribosomal subunits. G1 accumulation was also observed, plausibly as a downstream consequence of impaired ribosome production rather than evidence that Rrp36 is primarily a cell-cycle signaling protein. (gerus2010evolutionarilyconservedfunction pages 7-8, gerus2010evolutionarilyconservedfunction pages 8-10)
The strongest quantitative human data are:
No retrieved source directly established Q9P6P2 deletion viability, temperature sensitivity, growth rate, ribosome profile, or S. pombe pre-rRNA phenotype. Its essentiality therefore should not be inferred solely from severe depletion phenotypes in budding yeast.
No 2023–2024 publication specifically testing S. pombe Q9P6P2/SPAC823.04 was identified in the targeted searches. The principal gene-specific mechanistic source remains Gérus et al., published in March 2010, which combined budding-yeast genetics and preribosome biochemistry with human-cell knockdown experiments: https://doi.org/10.1128/MCB.00999-09. (gerus2010evolutionarilyconservedfunction pages 11-13, gerus2010evolutionarilyconservedfunction pages 7-8, gerus2010evolutionarilyconservedfunction pages 14-15)
The identity-control source is Bonnart et al., published in March 2012, which establishes that S. pombe SpUtp6/SPBC244.02c—not Rrp36—is the HCA66-related protein: https://doi.org/10.1093/nar/gks234. (bonnart2012mammalianhca66protein pages 10-11)
Accordingly, there is no defensible gene-specific “latest advance” from 2023–2024 to report. Recent general progress in ribosome-biogenesis structural biology should not be presented as Q9P6P2 evidence unless Rrp36 is explicitly resolved and assigned in the relevant structures.
Rrp36 currently has no established clinical, industrial, or therapeutic application specific to fission yeast. Its practical value is primarily as:
These are research uses inferred from the ortholog experiments, not documented real-world deployments of Q9P6P2.
A conservative database-quality annotation would be:
Rrp36 is a conserved RRP36-family nucleolar factor predicted to associate with early 90S/pre-40S preribosomes and promote early pre-rRNA processing required for 18S-rRNA maturation and 40S-subunit production. It is not a demonstrated enzyme. Functional and localization assignments for S. pombe Q9P6P2 are currently based mainly on orthology to experimentally characterized budding-yeast and human proteins.
Confidence is high for identity and family membership from the supplied UniProt/domain context; moderate-to-high for a nucleolar 90S/40S-biogenesis role because concordant experiments exist in divergent eukaryotes; and low or unresolved for the precise molecular interaction, direct RNA contacts, cleavage-site specificity in S. pombe, catalytic status beyond “none demonstrated,” essentiality, and organism-specific phenotype.
The most informative direct validation would combine endogenous Q9P6P2 tagging and nucleolar colocalization, conditional depletion, quantitative Northern mapping of S. pombe pre-rRNAs, polysome/ribosomal-subunit profiling, and affinity purification or proximity labeling. Rescue by wild-type Q9P6P2 and mutation of its conserved/basic regions would separate primary Rrp36 function from secondary consequences of reduced growth.
References
(gerus2010evolutionarilyconservedfunction pages 10-11): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.
(gerus2010evolutionarilyconservedfunction pages 4-7): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.
(gerus2010evolutionarilyconservedfunction pages 7-8): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.
(gerus2010evolutionarilyconservedfunction pages 14-15): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.
(bonnart2012mammalianhca66protein pages 10-11): Chrystelle Bonnart, Marie Gérus, Coralie Hoareau-Aveilla, Tamás Kiss, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Mammalian hca66 protein is required for both ribosome synthesis and centriole duplication. Nucleic Acids Research, 40:6270-6289, Mar 2012. URL: https://doi.org/10.1093/nar/gks234, doi:10.1093/nar/gks234. This article has 18 citations and is from a highest quality peer-reviewed journal.
(bonnart2012mammalianhca66protein pages 7-10): Chrystelle Bonnart, Marie Gérus, Coralie Hoareau-Aveilla, Tamás Kiss, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Mammalian hca66 protein is required for both ribosome synthesis and centriole duplication. Nucleic Acids Research, 40:6270-6289, Mar 2012. URL: https://doi.org/10.1093/nar/gks234, doi:10.1093/nar/gks234. This article has 18 citations and is from a highest quality peer-reviewed journal.
(gerus2010evolutionarilyconservedfunction pages 8-10): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.
(gerus2010evolutionarilyconservedfunction pages 11-13): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.
(gerus2010evolutionarilyconservedfunction pages 13-14): Marie Gérus, Chrystelle Bonnart, Michèle Caizergues-Ferrer, Yves Henry, and Anthony K. Henras. Evolutionarily conserved function of rrp36 in early cleavages of the pre-rrna and production of the 40s ribosomal subunit. Mar 2010. URL: https://doi.org/10.1128/mcb.00999-09, doi:10.1128/mcb.00999-09. This article has 40 citations and is from a domain leading peer-reviewed journal.