Noncooperative Metalation of Metallothionein 1a and Its Isolated Domains with Zinc
Bibliographic record
Abstract
Mammalian metallothioneins (MTs) are a family of small cysteine-rich proteins capable of binding 7 Zn(2+) or Cd(2+) ions into two distinct domains: an N-terminal β-domain that binds 3 Zn(2+) or Cd(2+) and a C-terminal α-domain that binds 4 Zn(2+) or Cd(2+). MT has been implicated in a number of physiological functions, including metal ion homeostasis, toxic metal detoxification, and as a protective agent against oxidative stress. Conventionally, MT has been understood to coordinate metal ions in a cooperative fashion. Under this mechanism of metalation, the only species of biological relevance would be the metal-free (apo-) form of the protein and the fully metalated (holo-) form of the protein. However, an increasing body of evidence suggests that metalation occurs in a noncooperative manner. If this latter mechanism is correct, then partially metalated forms of the protein will be stable and able to take part in cellular chemistry. We report in this paper conclusive evidence that shows that biologically essential zinc binds to MT in a noncooperative manner. In addition, we report for the first time the stability of a Zn(5)-MT species. The implications of these findings are discussed in terms of the mechanism of metalation.
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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".