TOR regulates the subcellular distribution of DIM2, a KH domain protein required for cotranscriptional ribosome assembly and pre-40S ribosome export
Bibliographic record
Abstract
Eukaryotic ribosome synthesis is a highly dynamic process that involves the transient association of scores of trans-acting factors to nascent pre-ribosomes. Many ribosome synthesis factors are nucleocytoplasmic shuttling proteins that engage the assembly pathway at early nucleolar stages and escort pre-ribosomes to the nucleoplasm and/or the cytoplasm. Here, we report that two 40S ribosome synthesis factors, the KH-domain protein DIM2 and the HEAT-repeats/Armadillo-domain and export factor RRP12, are nucleolar restricted upon nutritional, osmotic, and oxidative stress. Nucleolar entrapment of DIM2 and RRP12 was triggered by rapamycin treatment and was under the strict control of the target of rapamycin (TOR) signaling cascade. DIM2 binds pre-rRNAs directly through its KH domain at the 5'-end of ITS1 (D-A(2) segment) and, consistent with its requirements in early nucleolar pre-rRNA processing, is required for efficient cotranscriptional ribosome assembly. The substitution of a single and highly conserved amino acid (G207A) within the KH motif is sufficient to inhibit pre-rRNA processing in a fashion similar to genetic depletion of DIM2. DIM2 carries an evolutionarily conserved putative nuclear export sequence (NES) at its carboxyl-terminal end that is required for efficient pre-40S ribosome export. Strikingly, DIM2 and RRP12 are both involved in the nucleocytoplasmic translocation of pre-ribosomes, suggesting that this step in the ribosome assembly pathway has been selected as a regulatory target for the TOR pathway.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".