Biochemical and molecular characterization of AtPAP12 and AtPAP26: the predominant purple acid phosphatase isozymes secreted by phosphate‐starved <i>Arabidopsis thaliana</i>
Why this work is in the frame
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Bibliographic record
Abstract
Plant purple acid phosphatases (PAPs) belong to a large multigene family whose specific functions in Pi metabolism are poorly understood. Two PAP isozymes secreted by Pi-deficient (-Pi) Arabidopsis thaliana were purified from culture filtrates of -Pi suspension cells. They correspond to an AtPAP12 (At2g27190) homodimer and AtPAP26 (At5g34850) monomer composed of glycosylated 60 and 55 kDa subunit(s), respectively. Each PAP exhibited broad pH activity profiles centred at pH 5.6, and overlapping substrate specificities. Concanavalin-A chromatography resolved a pair of secreted AtPAP26 glycoforms. AtPAP26 is dual targeted during Pi stress because it is also the principal intracellular (vacuolar) PAP up-regulated by -Pi Arabidopsis. Differential glycosylation appears to influence the subcellular targeting and substrate selectivity of AtPAP26. The significant increase in secreted acid phosphatase activity of -Pi seedlings was correlated with the appearance of immunoreactive AtPAP12 and AtPAP26 polypeptides. Analysis of atpap12 and atpap26 T-DNA mutants verified that AtPAP12 and AtPAP26 account for most of the secreted acid phosphatase activity of -Pi wild-type seedlings. Semi-quantitative RT-PCR confirmed that transcriptional controls exert little influence on the up-regulation of AtPAP26 during Pi stress, whereas AtPAP12 transcripts correlate well with relative levels of secreted AtPAP12 polypeptides. We hypothesize that AtPAP12 and AtPAP26 facilitate Pi scavenging from soil-localized organophosphates during nutritional Pi deprivation.
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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 it