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 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".