Insights into a Single Rod-like Helix in Activated Radixin Required for Membrane−Cytoskeletal Cross-Linking
Bibliographic record
Abstract
The members of the ezrin-radixin-moesin (ERM) family of proteins function as membrane-cytoskeletal cross-linkers in actin-rich cell surface structures. ERM proteins are thereby thought to be essential for cortical cytoskeleton organization, cell motility, adhesion, and proliferation. These modular polypeptides consist of a central helix-rich region, termed the alpha-domain, that connects an N-terminal FERM domain required for membrane binding and a C-terminal region which contains a major actin-binding motif. Conformational regulation of ERM protein function occurs by association of the FERM and C-terminal domains, whereby the membrane- and actin-binding activities are mutually suppressed and the protein is thought to take an inactive "closed" form. Here we report in vitro and in vivo studies of radixin to address the role of the alpha-domain in conformational activation of ERM proteins. Remarkably, an isolated alpha-domain comprised of radixin(311-469) forms a monomeric, stable helical rod that spans 240 A in length from the N-terminus to the C-terminus, most likely stabilized by extensive salt bridge interactions. By fusing green fluorescent protein variants to the FERM and C-terminal domains, we probed in vitroconformational changes impacted by the presence of the alpha-domain using fluorescence resonance energy transfer (FRET). Furthermore, deletion of this unusually long alpha-helical structure (radixin residues 314-411) prevents ERM membrane targeting in vivo.
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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".