Crystal structure of a tandemly repeated PTP‐like <i>myo</i> ‐inositol hexa <i>kis</i> phosphatase (phytase)
Bibliographic record
Abstract
Inositol phosphatases are involved in a variety of eukaryotic and prokaryotic cellular functions. Phytases are a phosphatase class that preferentially hydrolyze myo ‐inositol hexa kis phosphate (InsP 6 ) to lower phosphorylated myo ‐inositols. InsP 6 is the most abundant inositol phosphate in the cell and has been implicated in important cellular processes including DNA repair, mRNA export, cellular signaling, endocytosis and vesicular trafficking. The phytase expressed by Mitsuokella multacida (PhyAmm) is composed of tandemly repeated domains each possessing a protein tyrosine phosphatase active site signature sequence. Mutation of the N‐terminal catalytic cysteine (C250) to serine has no effect on the catalytic activity of the protein, whereas mutation of the equivalent residue in the C‐terminal domain (C548) completely inactivates the enzyme. These results indicate that despite the presence of all the catalytic residues, the N‐terminal domain of PhyAmm is inactive against InsP 6 . The crystal structure of PhyAmm was solved to further examine the role of the inactive domain. A comparison of the active and inactive domains has identified differences that may explain why the N‐terminal domain lacks catalytic activity, and suggests this domain may be capable of hydrolyzing lower phosphorylated myo ‐inositols. This work is supported by the Natural Sciences and Engineering Research Council of Canada and the Alberta Ingenuity Fund.
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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 | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".