Editorial: The isotypes of α, β and γ tubulin: From evolutionary origins to roles in metazoan development and ligand binding differences
Bibliographic record
Abstract
Editorial on the Research Topic The isotypes of α, β and γ tubulin: From evolutionary origins to roles in metazoan development and ligand binding differences Tubulin, found in all eukaryotes, exists in many forms: α, β, γ, and others.α and β form a heterodimer, polymerizing into microtubules, often nucleated by γ.Not surprisingly, for a protein that has existed since eukaryotic cells appeared billions of years ago, α, β, and γ diverged into different forms---isotypes---with different amino acid sequences encoded by different genes.This Research Topic explores tubulin isotypes and addresses their evolutionary, functional and medical significance. Evolutionary significance of tubulin isotypesFor a better perspective we must dive into the origin of tubulin, which is itself a member of a superfamily, including the eubacterial FtsZ as well as other proteins found in many prokaryotes and even viruses.These proteins form filaments and bind to GTP and have similar primary and tertiary structures (reviewed in Ludueña, 2013).An algorithm based on a model for the evolution of the genetic code, places FtsZ among the oldest 10 proteins, coming in third after ferredoxin and slightly older than proteins involved in nucleic acid metabolism (Davis, 1999;Davis, 2002).FtsZ participates in bacterial cell division and binds to membranes and actin filaments.Fulton's introductory essay explains the origin of the "multi-tubulin hypothesis," the idea that there have to be distinct types of tubulin performing different functions.In Naegleria, a unicellular organism that goes from an amoeboid to a flagellated stage, the former contains microtubules that form the mitotic spindle, while the latter has them forming flagella.The Fulton laboratory showed, using 35 S-methionine, that flagellar tubulin formed de novo, meaning that the mitotic spindle tubulins were not recycled into flagella, suggesting that there had to be more than one set of αand β-tubulins.Gene sequencing
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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 | 0.005 | 0.012 |
| Meta-epidemiology (narrow) | 0.004 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.002 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.005 | 0.004 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.009 | 0.012 |
| Insufficient payload (model declined to judge) | 0.029 | 0.019 |
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".