C-spine mutations of protein kinase C and Akt as a novel generalizable approach to create stable pseudokinases
Bibliographic record
Abstract
Protein kinases function not only through their catalytic phospho-transfer activity but also by noncatalytic scaffold mechanisms. Introduction of mutations to inactivate catalysis provides a tool to differentiate between the two; however, kinase-inactivating mutations may alter the structure of the kinase domain and perturb scaffold functions. Here, we developed a strategy that prevents ATP binding, thereby preventing catalysis, while stabilizing the active conformation of the kinase domain. This approach leverages the structural role of ATP in assembling the catalytic spine (C-spine), a hydrophobic core essential for the active conformation. Specifically, we substituted Val or Ala residues proximal to the binding position of the adenosine ring of ATP with Phe in three protein kinase C isozymes (PKCβII, γ, and θ) and Akt1. Structural modeling suggests that Phe substitutions at these positions are a surrogate for the adenosine ring of ATP to assemble the C-spine. Live-cell imaging using genetically encoded PKC and Akt activity reporters reveals that C-spine mutations abolish kinase activity. Furthermore, phosphorylation of the hydrophobic motif, an autophosphorylation site, is abolished in C-spine mutants of PKC family members and reduced in C-spine mutants of Akt1, independent of epidermal growth factor stimulation. In PKCβII, these C-spine mutations accelerate plasma membrane translocation, consistent with impaired autoinhibition due to the lack of hydrophobic motif phosphorylation. Despite adopting reduced autoinhibition, turnover experiments with PKCθ reveal C-spine mutants do not impair the stability of the full-length PKC. The generation of pseudokinases by C-spine mutations provides a generalizable strategy for elucidating noncatalytic kinase functions.
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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".