Activation mechanism, functional role and shedding of glycosylphosphatidylinositol‐anchored Yps1p at the <i>Saccharomyces cerevisiae</i> cell surface
Bibliographic record
Abstract
Yeast cell wall assembly is a highly regulated and dynamic process. A class of cell surface aspartic peptidases anchored by a glycosylphosphatidylinositol (GPI) group, collectively known as yapsins, was proposed to be involved in cell wall construction. The Saccharomyces cerevisiae Yps1p, the prototypal yapsin, is processed internally within a loop region to produce an alpha/beta two-subunit enzyme. Here we investigated the activation mechanism of GPI-anchored Yps1p and identified some of its substrates. We report that all activation steps of GPI-Yps1p take place at the cell surface and are regulated by the environmental pH. GPI-Yps1p is active in vivo at pH 6.0 and pH 3.0 and functions as a sheddase for a subset of GPI-anchored enzymes, including itself and the Gas1 glucanosyltransferase. Importantly, while native GPI-Yps1p weakly suppresses many phenotypes associated with the yeast kex2Delta mutant, loop mutants that interfere with conversion into the two-subunit enzyme restore the kex2Delta phenotypes to near wild type level. We propose that cleavage of this internal loop region plays an important regulatory function through stimulating its shedding activity. Collectively, our data provide a direct link between the pH regulation of yeast cell wall assembly and the activity of a yapsin.
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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 | 0.000 | 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) | 0.000 | 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 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".