Crystallization Characteristics of Calmodulin in Complex and Fused with Calcineurin Peptide
Bibliographic record
Abstract
Calcineurin (CN) is the only serine/threonine protein phosphatase under the control of Ca 2+ /calmodulin (CaM). CaM up-regulates the phosphatase activity of CN by binding to CaM-binding domain (CBD) of calcineurin subunit A. However, the disordered structure of CBD has not been resolved in all crystal structures of CN determined so far. To gain insight into the structural basis by which CaM binds to CBD of CN and exerts its interaction, we have created a fusion construction in which CBD is covalently linked to CaM via a 5-glycine flexible linker and solved the crystal structure. However, the structure that displays a novel CaM binding conformation is still debatable because of the linker between CaM and CBD and/or crystallization conditions, which may affect protein packing. To investigate whether or not the novel CaM–CBD structure could potentially represent an artifact, we have attempted cocrystallization of CaM in complex with CBD and have now obtained cocrystals in two crystal forms. Comparison of crystallization conditions, crystal morphologies, and crystal parameters indicated that both CaM in complex with CBD peptide and CaM–CBD peptide chimera have the same crystal characteristics and behaviors in crystal growth under the similar crystallization conditions. The results provide direct evidence that the glycine linker did not affect the protein structure and the crystallization conditions did not result in different conformations. The advantage of using the fusion construct includes a higher yield of the CBD peptide driven by robust expression of CaM and the ease to purify both components simultaneously.
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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".