Chemical Genetics of Zipper-interacting Protein Kinase Reveal Myosin Light Chain as a Bona Fide Substrate in Permeabilized Arterial Smooth Muscle
Bibliographic record
Abstract
Zipper-interacting protein kinase (ZIPK) has been implicated in Ca(2+)-independent smooth muscle contraction, although its specific role is unknown. The addition of ZIPK to demembranated rat caudal arterial strips induced an increase in force, which correlated with increases in LC(20) and MYPT1 phosphorylation. However, because of the number of kinases capable of phosphorylating LC(20) and MYPT1, it has proven difficult to identify the mechanism underlying ZIPK action. Therefore, we set out to identify bona fide ZIPK substrates using a chemical genetics method that takes advantage of ATP analogs with bulky substituents at the N(6) position and an engineered ZIPK capable of utilizing such substrates. (32)P-Labeled 6-phenyl-ATP and ZIPK-L93G mutant protein were added to permeabilized rat caudal arterial strips, and substrate proteins were detected by autoradiography following SDS-PAGE. Mass spectrometry identified LC(20) as a direct target of ZIPK in situ for the first time. Tissues were also exposed to 6-phenyl-ATP and ZIPK-L93G in the absence of endogenous ATP, and putative ZIPK substrates were identified by Western blotting. LC(20) was thereby confirmed as a direct target of ZIPK; however, no phosphorylation of MYPT1 was detected. We conclude that ZIPK is involved in the regulation of smooth muscle contraction through direct phosphorylation of LC(20).
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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 | 0.001 | 0.001 |
| 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".