Modulation of Rho and Cytoskeletal Protein Attachment to Membranes by a Prenylcysteine Analog
Bibliographic record
Abstract
The GTPases Rho regulate the assembly of polymerized actin structures. Their C-terminal sequences end with the CAAX motif that undergo a lipidation of the cysteine residue. Analogs to the C-terminal ends of Rho proteins, N-acetyl-S-all-trans, trans-farnesyl-L-cysteine and N-acetyl-S-all-trans-geranylgeranyl-L-cysteine, wereused to analyze the role of prenylation in their membrane association. Silver-stained gels indicated that N-acetyl-S-all-trans-geranylgeranyl-L-cysteine treatment released only a few proteins of 20, 46, and 60 kDa. Western blot analysis showed that N-acetyl-S-all-trans-geranylgeranyl-L-cysteine released RhoB (10%), RhoA (28%), and Cdc42 (95%) from membranes, whereas N-acetyl-S-all-trans and trans-farnesyl-L-cysteine did not. Rab1, which possesses two geranylgeranyl groups, was also strongly extracted by N-acetyl-S-all-trans-geranylgeranyl-L-cysteine, whereas Ras, which is farnesylated, was not. Furthermore, N-acetyl-S-all-trans-geranylgeranyl-L-cysteine was very efficient (95%) in dissociating actin and tubulin from membranes but not integral membrane protein P-glycoprotein and sodium/phosphate cotransporter NaP(i)-2. The extraction of Rho and cytoskeletal proteins occurred below the critical micellar concentration of N-acetyl-S-all-trans-geranylgeranyl-L-cysteine. Membrane treatments with 0.7 m KI totally extracted actin, whereas 70% of Cdc42 was released. Actin was, however, insoluble in Triton X-100-treated membranes, whereas this detergent extracted (80%) Cdc42. These data show that Rho proteins and actin are not physically bound together and suggest that their extraction from membranes by N-acetyl-S-all-trans-geranylgeranyl-L-cysteine likely occurs via different mechanisms.
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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 | 0.001 |
| 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".