Nuclear localization signals in the <i>Xenopus</i> FGF embryonic early response 1 protein
Bibliographic record
Abstract
Xenopus early response 1 (XER1) is a fibroblast growth factor-inducible transcription factor whose developmentally regulated nuclear localization is thought to be important in the control of cell differentation during embryonic development [Luchman et al., Mech. Dev. 80 (1999) 111-114]. Analysis of the XER1 amino acid sequence revealed four regions which contain potential nuclear localization sequences (NLSs). Using mutant XER1 proteins and portions of XER1 fused to green fluorescent protein (GFP) transfected into NIH 3T3 cells, we have determined that only one of these, NLS4, located near the carboxy-terminus of XER1, is necessary and sufficient for targeting exclusively to the nucleus. Of the other three predicted NLS sequences, only NLS1, consisting of the sequence (138)RPRRCK(143) was shown to function as a cryptic, weak NLS. NLS4 contains a core region consisting of the sequence (463)RPIKRQRMD(471) which is similar to the core NLS directing the human c-MYC protein to the nucleus. The core sequence is flanked by a predicted cdc2/protein kinase A phosphorylation motif, however mutation of the serine(472) to alanine or aspartic acid had no detectable effect on accumulation of GFP-XER1 fusion proteins in the nucleus, demonstrating that this putative phosphorylation site plays no role in regulating nuclear transport.
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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 | 0.002 |
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".