Human DDX21 binds and unwinds RNA guanine quadruplexes
Bibliographic record
Abstract
Guanine quadruplexes (G4s) are an important structure of nucleic acids (DNA and RNA) with roles in several cellular processes. RNA G4s require specialized unwinding enzymes, of which only two have been previously identified. We describe the results of a simple and specific mass spectrometry guided method used to screen HEK293T cell lysate for G4 binding proteins. From these results, we validated the RNA helicase protein DDX21. DDX21 is an established RNA helicase, but has not yet been validated as a G4 binding protein. Through biochemical techniques, we confirm that DDX21-quadruplex RNA interactions are direct and mediated via a site of interaction at the C-terminus of the protein. Furthermore, through monitoring changes in nuclease sensitivity we show that DDX21 can unwind RNA G4. Finally, as proof of principle, we demonstrate the ability of DDX21 to suppress the expression of a protein with G4s in the 3΄ UTR of its mRNA.
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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".