Reassociation and translocation of glycoprotein IIB-IIIA in EDTA-treated human platelets
Bibliographic record
Abstract
Platelet membrane glycoproteins IIb and IIIa form a calcium-dependent heterodimer that plays a key role in platelet adhesion and aggregation. The present objective was to measure the dissociation and reassociation of GPIIb-IIIa by flow cytometric analysis of platelets labelled with mAbs specific for the glycoprotein complex or each monomer. In agreement with previous studies, EDTA chelation of extracellular calcium, [Ca2+]o, dissociated the heterodimer in a time and temperature dependent manner. Agonist stimulation of EDTA-treated platelets induced subunits to reassociate with the following order of potency: thrombin > collagen > ADP. Two-fold increases in GPIIb-IIIa and GPIIb indicate that thrombin caused reassociation of surface subunits and concurrent translocation of complexes from intracellular pools. The latter was partially inhibited by cytochalasin B thus indicating that a subpopulation of GPIIb-IIIa required cytoskeletal remodelling for translocation. Surface GPIIIa as reported by anti-CD61 declined more and upregulated less compared with GPIIb-IIIa or GPIIb. Results suggest that EDTA incubation might have altered the conformation of this epitope and decreased mAb binding. Collagen induced GPIIb-IIIa reassociation but not translocation of cryptic complexes. BAPTA suppression of rises in cytosolic calcium concentration or low [Ca2+]o inhibited GPIIb-IIIa reassociation, thus indicating that this reaction was driven by signal transduction. Thrombin and collagen induced a comparable level of aggregation of EDTA-treated platelets despite a 3-fold difference in cell surface GPIIb-IIIa. It is concluded that the effects of EDTA on GPIIb-IIIa dissociation and loss of adhesive functions are largely but not completely reversible.
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".