Transcriptional Properties of Ptx1 and Ptx2 Isoforms
Bibliographic record
Abstract
The Ptx (Pitx) family of homeobox transcription factors comprises Ptx1, Ptx2 and Ptx3. Ptx1 and Ptx2 are expressed in the stomodeum and its derivatives including the pituitary, as well as in mesodermal derivatives, whereas Ptx3 is expressed in one neuronal lineage of the brain and in the eyes. A large set of downstream target genes have been identified for Ptx1 in the pituitary gland where it acts as a pan-pituitary regulator of transcription. In particular, Ptx1 contributes to promoter- and lineage-specific transcription by interaction with cell-restricted factors such as SF-1, Egr-1, Pit1, and the basic helix-loop-helix heterodimer NeuroD1/Pan1. We describe the cloning from pituitary cells and the characterization of a Ptx1 isoform, named Ptx1b, generated by alternative promoter usage. The two Ptx1 and two Ptx2 isoforms have similar in vitro DNA binding specificities and they all activate transcription driven by a panel of pituitary promoters, including those for proopiomelanocortin, alphaGSU, LHbeta, FSHbeta, GnRH-R, TSHbeta, PRL, and GH. Also like Ptx1, the Ptx1b, Ptx2a, and Ptx2b transcription factors synergize with the structurally unrelated factors SF-1, Egr-1, Pit1, and NeuroD1/Pan1 to activate promoter-specific transcription. In conclusion, the pituitary transcriptional activities of the four Ptx isoforms do not appear to be dependent on the variant N-termini of these factors.
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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".