Ca2+-dependent and phospholipid-independent binding of annexin 2 and annexin 5
Bibliographic record
Abstract
Annexins are a family of homologous proteins that associate with anionic phospholipid (aPL) in the presence of Ca(2+). Evidence that the function of one annexin type may be regulated by another was recently reported in studies investigating cytomegalovirus-aPL interactions, where the fusogenic function of annexin 2 (A2) was attenuated by annexin 5 (A5). This observation suggested that A2 may bind directly to A5. In the present study, we demonstrated this interaction. The A2-A5 complex was first detected utilizing (covalently linked) fluorescein-labelled A5 (F-A5) as a reporter group. The interaction required concentrations of Ca(2+) in the millimolar range, had an apparent dissociation constant [ K (d)(app)] of 1 nM at 2 mM Ca(2+) and was independent of aPL. A2 bound comparably with F-A5 pre-equilibrated with an amount of aPL that could bind just the F-A5 or to an excess amount of aPL providing sufficient binding sites for all of F-A5 and A2. A2-A5 complex formation was corroborated in an experiment, where [(125)I]A2 associated in a Ca(2+)-dependent manner with A5 coated on to polystyrene. Surface plasmon resonance was used as a third independent method to demonstrate the binding of A2 and A5 and, furthermore, supported the conclusion that the monomeric and tetrameric forms of A2 bind equivalently to A5. Together these results demonstrate an A2-A5 interaction and provide an explanation as to how A5 inhibits the previously reported A2-dependent enhancement of virus-aPL fusion.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".