NCU08595 evidence notes

NCU08595 is a Rpf2-family ribosome assembly factor with a Brix RNA-binding domain. By conservation with characterized fungal Rpf2, it associates with Rrs1, binds 5S rRNA and promotes incorporation of the 5S ribonucleoprotein particle into nucleolar large-subunit precursors. This assembly step supports large-subunit rRNA maturation.

Identity and provenance

The exact current accession is Q7SCN3; NCU08595 is retained as the current locus identifier. No independently established formal gene-symbol replacement was found. Original claims are preserved in NCU08595-protnlm-source.json from the live API snapshot retrieved 2026-09-09T03:00:51.831347+00:00. The current sequence is not proven to be the prediction-time input, and placeholder API dates do not establish release or training membership.

Primary evidence and justified transfer

• PMID:25855814 "Proteins Rpf2 and Rrs1 are required for 60S ribosomal subunit maturation."
• PMID:25855814 "gel shift analysis revealed that the Rpf2-Rrs1 complex binds directly
  to 5S rRNA."

The specific domain/family observation used is DR InterPro; IPR039770; Rpf2.. Family membership and characterized relatives establish the inference; ARBA or AI-generated names are not independent functional evidence. PAINT is a curator-reviewed ancestral assertion, not donor-count evidence.

Unresolved assertions

No unresolved GOA assertion remains at the reviewed level of specificity. Experimental observations on relatives are distinguished from target observations.

Falcon report appraisal

The actual Falcon report supports a conserved Rpf2-Rrs1 assembly-factor role and correctly distinguishes direct fungal-homolog assays from absent target assays. Its principal additional paper, PMID:26117542, was cached and inspected: the Aspergillus complex structure and biochemical data place it against 5S rRNA, RpL5 and Rsa4. Exact excerpt: "The heterodimer forms
specific contacts with the 5S rRNA, RpL5 and the biogenesis factor Rsa4." This agrees with PMID:25855814 used for the main judgment. Specific residue numbers, essentiality and an autonomous nuclease function are not assigned to NCU08595.

2026-10-21 — Full re-review, independent of the ProtNLM2 predictions

ProtNLM2 output was not consulted for this re-review.

Identity

• Q7SCN3 is the only UniProt entry for locus NCU08595 (TrEMBL, PE 3, 341 aa, sequence version 1). It is the complete product, not a fragment, isoform or alternative gene model. Its length matches PTHR12728:SF0 members (C. thermophilum G0SF80 350 aa, S. cerevisiae P36160 344 aa, human Q9H7B2 306 aa). The Brix domain (FT 28..249) is complete.
• PANTHER: PTHR12728 (BRIX DOMAIN CONTAINING PROTEIN) / SF0 (RIBOSOME PRODUCTION FACTOR 2 HOMOLOG), per the UniProt DR line. The family review interpro/panther/PTHR12728/PTHR12728-review.yaml puts NCU08595 in SF0 as a representative, so the two agree. Q7SCN3 is not among the 11 sampled rows of PTHR12728-entries.csv, but that is a sampling gap, not a conflicting placement.

Evolutionary grounding (new analysis)

• NCU08595-bioinformatics/rpf2_motif_rereview.py → RESULTS-rereview.md. NCU08595 is 74% identical to C. thermophilum Rpf2 and 46% identical to S. cerevisiae Rpf2. The 5S rRNA loop E-binding KKR loop is at K94-K96 in N. crassa, C. thermophilum and yeast. The residue aligned to yeast R236 (5S rRNA binding, PMID:25855814) is R242 in NCU08595.
• The direct EMSA in PMID:26117542 used the C. thermophilum (Sordariales) protein, which is in the same PANTHER subfamily and the same order as Neurospora. This is the best-grounded transfer available.
• PAINT node PTN000296192 propagates rRNA binding, nucleolus and LSU-rRNA maturation. It does not propagate the yeast pre-60S complex CC terms. I read that omission as deliberate and do not add them.

Changes from the previous review

• GO:0019843 rRNA binding (IBA + IEA): ACCEPT → MODIFY to GO:0008097 5S rRNA binding, which is the specific ligand shown for the ortholog. Core MF changed to match.
• GO:0000470 maturation of LSU-rRNA: ACCEPT → MODIFY to GO:0000463, the descendant already present by IBA (correct-but-general rule).
• GO:0042254 ribosome biogenesis: MODIFY now lists both GO:0000027 and GO:0000463.
• GO:0000027 is now stated to be the primary process. Rpf2-Rrs1 physically recruits and holds the 5S RNP, so it does part of the work of assembly. 27SB processing is downstream, and GO:0000463 is retained under the assembly-factor convention.
• Added PMID:26117542 as a reference and rewrote the description.
• No NEW annotations. NCU08595 itself has no experimental data.

Relative to review next

• S. cerevisiae RPF2 (P36160, SGD:S000001789) is in the same PANTHER subfamily SF0, is the seed donor of PAINT node PTN000296192, and is the best-characterized ortholog. There is no review in the repo (no genes/yeast/RPF2, no P36160 hit).
• Modules: no module under modules/ covers Rpf2/5S RNP assembly. The grep hits were base64 noise in falcon artifacts.