Luminal Ca<sup>2+</sup> regulation of RyR1 Ca<sup>2+</sup> channel leak activation and inactivation in sarcoplasmic reticulum membrane vesicles
Bibliographic record
Abstract
In this study, we tested the hypothesis that the RyR1 Ca2+ channel closure is sensitive to outward trans-SR membrane Ca2+ gradients established by SERCA1 pumping. To perform these studies, we employed stopped-flow rapid-kinetic fluorescence methods to measure and assess how variation in trans-SR membrane Ca2+ distribution affects evolution of RyR1 Ca2+ leaks in RyR1/ CASQ1/SERCA1-rich membrane vesicles. Our studies showed that rapid filling of a Mag-Fura-2-sensitive free Ca2+ pool during SERCA1-mediated Ca2+ sequestration appears to be a crucial condition allowing RyR1 Ca2+ channels to close once reloading of luminal Ca2+ stores is complete. Disruption in the filling of this pool caused activation of Ruthenium Red inhibitable RyR1 Ca2+ leaks, suggesting that SERCA1 pump formation of outward Ca2+ gradients is an important aspect of Ca2+ flux control channel opening and closing. In addition, our observed ryanodine-induced shift in luminal Ca2+ from free to a CTC–Ca+-sensitive, CASQ1-associated bound compartment underscores the complex organization and regulation of SR luminal Ca2+. Our study provides strong evidence that RyR1 functional states directly and indirectly influence the compartmentation of luminal Ca2+. This, in turn, is influenced by the activity of SERCA1 pumps to fill luminal pools while synchronously reducing Ca2+ levels on the cytosolic face of RyR1 channels.
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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 | 0.000 |
| 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".