Protein Synthesis Initiation in Eukaryotes:<scp>IRES</scp>‐mediated Internal Initiation
Bibliographic record
Abstract
Abstract The major mechanism of translation initiation in eukaryotes involves recognition of the cap structure at the 5′ end of the mRNA by the cap‐binding protein eIF4E. Internal ribosome entry sites (IRES) are specialised RNA sequences that are capable of recruiting ribosomes to an internal position of an mRNA in a cap‐independent manner. Many viruses have evolved this alternative pathway to initiate translation. Viral IRESs bind ribosomes by several mechanisms that require different sets of canonical initiation factors. In addition, IRES activity is modulated by IRES trans‐acting factors (ITAFs). Some cellular mRNAs are suggested to contain IRESs, as they function in cells under stress and other conditions when cap‐dependent initiation is inhibited. However, solid evidence for internal ribosome entry onto many of these mRNAs is lacking. Key Concepts In eukaryotes, the majority of mRNAs are translated by a 5′ end‐dependent mechanism, in which the mRNA 5′ cap structure recruits the translation machinery. Specific RNA elements, termed internal ribosome entry sites (IRESs), can direct ribosomes to internal positions of mRNAs to initiate translation. IRESs in viral RNA genomes differ significantly with respect to their structure and initiation factor requirements. In addition to some canonical initiation factors, IRES‐mediated translation may require ITAFs (IRES trans ‐acting factors). Many cellular mRNAs are suggested to possess IRESs, as they remain active under a number of pathophysiological stress conditions when cap‐dependent translation is inhibited. The authenticity of some cellular IRESs remains controversial as being not confirmed in recently developed stringent tests for IRES activity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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 teacher head, 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".