The Dihydrofolate Reductase Protein-Fragment Complementation Assay: A Survival-Selection Assay for Large-Scale Analysis of Protein–Protein Interactions
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Protein-fragment complementation assays (PCAs) can be used to study protein-protein interactions (PPIs) in any living cell, in vivo or in vitro, in any subcellular compartment or membranes. Here, we present a detailed protocol for performing and analyzing a high-throughput PCA screening to study PPIs in yeast, using dihydrofolate reductase (DHFR) as the reporter protein. The DHFR PCA is a simple survival-selection assay in which Saccharomyces cerevisiae DHFR (scDHFR) is inhibited by methotrexate, thus preventing nucleotide synthesis and causing arrest of cell division. Complementation of cells with a methotrexate-insensitive murine DHFR restores nucleotide synthesis, allowing cell proliferation. The methotrexate-resistant DHFR has two mutations (L22F and F31S) and is 10,000 times less sensitive to methotrexate than wild-type scDHFR, but retains full catalytic activity. The DHFR PCA is sensitive enough for PPIs to be detected for open reading frame (ORF)-PCA fragments expressed off of their endogenous promoters.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 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) | 0.000 | 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 it