Mastoparan Rapidly Activates Plant MAP Kinase Signaling Independent of Heterotrimeric G Proteins
Bibliographic record
Abstract
It has long been known that mastoparan (MP), a cationic, amphiphilic tetradecapeptide isolated from wasp venom, is capable of directly stimulating the guanine nucleotide exchange reaction of the α-subunit of animal heterotrimeric G proteins via a mechanism analogous to that of G protein coupled receptors. This leads to a myriad of downstream events including the activation of mitogen-activated protein kinases (MAPKs). Here, we show that MP induction of plant MAPK signaling does not require the participation of either the Gα- or Gβ-subunits of the plant heterotrimeric G proteins, but is reliant on reactive oxygen species (ROS), a cognate MAPKK, and influx of extracellular Ca2+ ions. While this does not preclude a role for a heterotrimeric G protein in MAPK signaling, it raises concern about the conclusions drawn from published experiments using MP. Gα-, Gβ-, and Gγ-homologs have been identified in Arabidopsis and other plant species (Ma et al., 1990; Gotor et al., 1996; Lee and Assmann, 1999; Saalbach, et al., 1999; Mason and Botella, 2000). In Arabidopsis, a single prototypical Gα-(Arabidopsis G PROTEIN, ALPHA SUBUNIT1 [GPA1]) and one prototypical Gβ-(Arabidopsis G PROTEIN, BETA SUBUNIT1 [AGB1]) subunit and potentially, two Gγ-subunits (Arabidopsis G PROTEIN, GAMMA SUBUNIT1 [AGG1 and AGG2]), are found. Interaction has been detected between the Arabidopsis Gγ- and Gβ-subunits (Mason and Botella, 2000; for review, see Jones, 2002), and evidence has been obtained for in vitro and in vivo interaction of GPA1 and Gβ (J.-G. Chen, J.S. Liang, and A.M. Jones, unpublished data).
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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) | 0.001 | 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 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".