Insulin-Like Growth Factor (IGF)-Binding Protein-3 (IGFBP-3) Binds to Fibronectin (FN): Demonstration of IGF-I/IGFBP-3/FN Ternary Complexes in Human Plasma1
Bibliographic record
Abstract
We used a yeast two-hybrid system to identify binding partners for insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3). A partial complementary DNA encoding the carboxyl-terminal of fibronectin (FN), including the cell binding site, the heparin-binding domain, and the fibrin-binding domain, was identified in a screen of a human placental complementary DNA library. The interaction of IGFBP-3 with FN and the 40-kDa heparin-binding carboxyl-terminal fragment of FN was confirmed using Western ligand blotting. Both glycosylated and nonglycosylated IGFBP-3 bound to FN with a K(d) of approximately 0.3 nmol/L. IGF-I and IGFBP-1 had no effect on IGFBP-3 binding to FN. Competitive inhibition of IGFBP-3 binding to FN was observed in the presence of IGFBP-5 and heparin. The binding affinity of the immobilized IGFBP-3/FN complex for [(125)I]IGF-I (K(d) = 0.8 nmol/L) was similar to that of IGFBP-3 alone. The presence of IGF-I/IGFBP-3/FN ternary complexes in human plasma was demonstrated by coimmunoprecipitation of IGFBP-3 and [(125)I]IGF-I with anti-FN monoclonal antibody. These data indicate that FN may have a role in the transportation of IGFBP-3 and IGF-I in the circulation and the sequestration of these proteins in tissues.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".