Nucleoplasmin Binds Histone H2A-H2B Dimers through Its Distal Face*
Bibliographic record
Abstract
Nucleoplasmin (NP) is a pentameric chaperone that regulates the condensation state of chromatin extracting specific basic proteins from sperm chromatin and depositing H2A-H2B histone dimers. It has been proposed that histones could bind to either the lateral or distal face of the pentameric structure. Here, we combine different biochemical and biophysical techniques to show that natural, hyperphosphorylated NP can bind five H2A-H2B dimers and that the amount of bound ligand depends on the overall charge (phosphorylation level) of the chaperone. Three-dimensional reconstruction of NP/H2A-H2B complex carried out by electron microscopy reveals that histones interact with the chaperone distal face. Limited proteolysis and mass spectrometry indicate that the interaction results in protection of the histone fold and most of the H2A and H2B C-terminal tails. This structural information can help to understand the function of NP as a histone chaperone.
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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) | 0.001 | 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".