Interactions between Kinase Scaffold MP1/p14 and Its Endosomal Anchoring Protein p18
Bibliographic record
Abstract
Scaffold and adaptor proteins provide means for the spatial organization of signaling cascades. MP1 is a scaffold protein in the RAF/MEK/ERK pathway and together with p14 forms a heterodimer that was shown to be responsible for localization of MEK to the late endosomal compartment. However, the mechanism by which MP1/p14 tethers MEK to the endosomal membrane was not resolved. Recently, an adaptor protein p18 was identified as a binding partner of MP1/p14. p18 is attached to the endosomal surface by myristoyl and palmitoyl groups located at the N-terminus of the protein and tethers the signaling complex to the cytoplasmic surface of late endosomes. p18 expressed in E. coli is retained in inclusion bodies, and we developed a protocol to refold it from the denatured state. Coexpression of p18 with MP1/p14 leads to a soluble protein complex. We examined the interaction of p18 with the MP1/p14 constitutive heterodimer. We cloned various constructs of p18 and characterized their behavior and interactions with MP1/p14 in vitro using SEC and pull-down assays. We determined that the refolded p18 is a monomer in solution with molten globule characteristics. Its binding to MP1/p14 promotes folding and ordering. We also identified a proteolytically stable fragment of p18 and showed that it binds to MP1/p14 with similar affinity to the full-length construct and determined an apparent dissociation constant in the low micromolar range for the interaction. Finally, we show that the ∼60 C-terminal residues of p18 are not required for in vitro interaction with MP1/p14 heterodimer, in contrast to previously reported findings showing that truncation of 41 C-terminal residues of p18 prevents endosomal localization of MP1/p14.
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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".