Calpain‐mediated degradation of reversibly oxidized protein‐tyrosine phosphatase 1B
Bibliographic record
Abstract
Protein‐tyrosine phosphatases (PTPs) are regulated by reversible inactivating oxidation of the catalytic‐site cysteine. We have previously shown that reversible oxidation upon UVA irradiation is followed by calpain‐mediated PTP degradation. Here, we address the mechanism of regulated cleavage and the physiological function of PTP degradation. Reversible oxidation of PTP1B in vitro strongly facilitated the association with calpain and led to greatly increased calpain‐dependent inactivating cleavage. Both oxidation‐induced association and cleavage depended exclusively on the presence of the catalytic (reversibly oxidized) cysteine residue 215. A major cleavage site was identified preceding amino acid position Ala77. In calpain‐deficient cells, insulin signaling was apparently diminished, consistent with a possible role for calpain in removing a negative regulator of insulin signaling. Reversibly oxidized PTP1B may be a target of calpain in this context. Structured digital abstract MINT‐7234580 : Calpain 4 (uniprotkb: P04632 ) and Calpain 1 (uniprotkb: P07384 ) physically interact ( MI:0915 ) with PTP1B (uniprotkb: P18031 ) by enzyme linked immunosorbent assay ( MI:0411 ) MINT‐7234562 , MINT‐7234481 : Calpain 4 (uniprotkb: P04632 ) and Calpain 1 (uniprotkb: P07384 ) cleave ( MI:0194 ) PTP1B (uniprotkb: P18031 ) by protease assay ( MI:0435 )
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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 | 0.001 |
| 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".