Cell- and heparin-binding domains of the hexabrachion arm defined by tenascin expression proteins
Bibliographic record
Abstract
We have produced a set of bacterial expression proteins corresponding to 10 segments of tenascin and two of fibronectin and tested them for heparin binding and cell adhesion. We used polymerase chain reaction cloning to terminate the segments precisely at domain boundaries. Heparin binding activity was mapped to two different tenascin segments: one comprising the fourth and fifth fibronectin type III domains, and to TNfbg, the fibrinogen-like terminal knob. TNfbg, but none of the other tanascin segments, also supported adhesion of primary rat embryo skin fibroblasts. The fibroblasts did not spread on TNfbg but remained rounded. Cell binding to TNfbg occurred in the presence or absence of divalent cations and was not inhibited by RGD peptides, suggesting that integrins are not involved. Fibroblast binding to TNfbg was strongly inhibited by soluble heparin, by treating the cells with heparitinase, or by culture conditions that cause undersulfation of proteoglycans. These observations suggest that cell attachment to TNfbg is mediated by cell surface proteoglycans. We have also made full-length cDNA constructs for the largest and smallest splice variants of human tenascin, as well as one truncated after the 14th epidermal growth factor-like domain, in the pNUT mammalian cell expression vector. Stably transfected baby hamster kidney cell lines secreted large quantities of tenascin, and this was assembled into normal hexabrachions, the arm length corresponding to the construct.
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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".