lsm6 evidence notes

Lsm6 is a conserved Sm-fold RNA-binding protein shared by the Lsm2-8 and Lsm1-7 complexes. Nuclear Lsm2-8 recognizes uridine-rich RNA ends and supports U6 snRNA function, spliceosome assembly and telomerase RNA protection. Cytoplasmic Lsm1-7 associates with Pat1 and promotes mRNA decapping and turnover. Fission yeast structures and RNA-binding assays establish the contribution of Lsm6 to these oligomeric RNA-binding assemblies.

Identity and prediction provenance

PomBase primary symbol lsm6, locus SPAC2F3.17c, current UniProt Q9UUI1. The supplied pre-release post-processed-2026_02_28k.xml is the source of the reviewed claims; its placeholder sequence, taxonomy and dates are not biological metadata. The current UniProt sequence is not established as the model input. Current API availability and published-list inclusion are separate properties; all biological judgments here concern the preserved original claims.

Primary evidence inspected

• [PMID:22615807 Crystal structures of Lsm3, Lsm4 and Lsm5/6/7 from Schizosaccharomyces pombe.] "RNA binding assays show that Lsm2/3 and Lsm5/6/7 bind to oligo(U) whereas no RNA binding is observed for Lsm3 and Lsm4. Analysis of the inter-subunit interactions in Lsm5/6/7 reveals the organization order among Lsm5, Lsm6 and Lsm7."
• [PMID:32518066 Molecular basis for the distinct cellular functions of the Lsm1-7 and Lsm2-8 complexes.] "The multi-ORF expression system was assembled into a single plasmid through ligation independent cloning as described for Lsm2–8, with the ORFs assembled in order Lsm6, Lsm3, Lsm2, Lsm1, Lsm4, Lsm7, and Lsm5."
• [PMID:16823372 ORFeome cloning and global analysis of protein localization in the fission yeast Schizosaccharomyces pombe.] "Next, we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein."

Evidence limits and adjudication

• GO:0005515 (KEEP_AS_NON_CORE): Retain the reported physical interaction as supporting complex-assembly evidence. Generic protein binding does not specify the nuclease or RNA-binding function and is not a useful core molecular-function summary.
• GO:0005682 (UNDECIDED): The original fission yeast spliceosome structure contains U2 and U5 particles, but the available abstract does not establish the specific Lsm6 contact or subcomplex assignment. Lsm6 is canonically an Lsm-ring component associated with U6, so the exact U2/U5 assignment requires inspection of the full structural model and supplementary protein identities. No misattribution is inferred from the abstract alone. The original PMID:26292707 remains the evidence source requiring resolution.
• GO:0005730 (KEEP_AS_NON_CORE): Curated phylogenetic evidence supports an ancillary nucleolar RNA-processing role, consistent with Lsm2-7 association with snoRNA in budding yeast. This is compatible with conserved RNA-binding ring biology but is less directly established for fission yeast Lsm6 than its Lsm1-7 and Lsm2-8 roles.

Primary reports are interpreted at the species, assay and subunit level. Abstract-only experimental annotations are not rejected because a title foregrounds another subunit. PAINT asserts inheritance from a curated ancestral node; donor count and target self-inclusion are not objections. ARBA overlap is recorded only as provenance, never as biological validation. CNN and LSP reflect established biological knowledge, without asserting training-data membership.

Telomerase assembly is supported at ring level by PMID:29422501: "Co-immunoprecipitation assays confirmed an interaction between Lsm3 and Lar7 (Fig. 5b), indicating that they co-exist as a complex. Their association was sensitive to the presence of RNase and was abolished in lar7-W103A and lar7-FV197EE mutants. In addition, an interaction between wild-type Lar7 and Trt1 was detected, which was also dependent on RNA (Fig. 5c). These data suggested that Lar7, LSm2–8 and Trt1 independently bind to TER1 to form the telomerase ribonucleoprotein complex.". This directly assays Lsm3 within the Lsm2–8 ring; inference to shared Lsm6 is grounded in target ring reconstitution, not a claim that Lsm6 was the tagged bait.

Provider report appraisal

The Falcon report and its structural evidence summary were inspected. It correctly distinguishes recombinant Lsm5/6/7 hexamers from physiological heteroheptamers, but its absence-of-complete-target-ring-evidence claim is incomplete: PMID:32518066 directly reconstitutes S. pombe Lsm1-7 and Lsm2-8. The primary full text was inspected.

Additional structural-source check: the publisher article PDF mirrored by Georgia Tech was inspected. Its main text describes heptameric Sm rings at U2 and U5. The accessible main text of PMID:26292707 describes Sm rings associated with U2 and U5, while fission yeast Lsm6 is experimentally established in Lsm RNA-binding rings. The exact protein identities and contacts underlying the PomBase U2/U5 assignment require resolution against the supplementary models and chain mappings. The broader spliceosome context is compatible with Lsm6 function, but it does not by itself settle this precise RNA or particle assignment. The experimental assignments remain UNDECIDED.