The Mammalian Cap-Specific m6Am RNA Methyltransferase PCIF1 Regulates Transcript Levels in Mouse Tissues
Bibliographic record
Abstract
The 5′ end of eukaryotic mRNAs is protected by the m 7 G-cap structure. The transcription start site nucleotide is ribose methylated (Nm) in many eukaryotes, whereas an adenosine at this position is further methylated at the N 6 position (m 6 A) by the mammalian Phosphorylated C-terminal domain (CTD)-interacting Factor 1 (PCIF1) to generate m 6 Am. Here, we show that although the loss of cap-specific m 6 Am in mice does not affect viability or fertility, the Pcif1 mutants display reduced body weight. Transcriptome analyses of mutant mouse tissues support a role for the cap-specific m 6 Am modification in stabilizing transcripts. In contrast, the Drosophila Pcif1 is catalytically dead, but like its mammalian counterpart, it retains the ability to associate with the Ser5-phosphorylated CTD of RNA polymerase II (RNA Pol II). Finally, we show that the Trypanosoma Pcif1 is an m 6 Am methylase that contributes to the N 6 , N 6 ,2′- O -trimethyladenosine (m 6 2 Am) in the hypermethylated cap4 structure of trypanosomatids. Thus, PCIF1 has evolved to function in catalytic and non-catalytic roles.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".