Monoclonal antibody 7H2.2 binds the C-terminus of the cancer-oocyte antigen SAS1B through the hydrophilic face of a conserved amphipathic helix corresponding to one of only two regions predicted to be ordered
Bibliographic record
Abstract
The structure of the antigen-binding fragment (Fab) of mouse monoclonal antibody 7H2.2 in complex with a 15-residue fragment from the metalloproteinase sperm acrosomal SLLP1 binding protein (SAS1B), which is a molecular and cellular candidate for both cancer therapy and female contraception, has been determined at 2.75 Å resolution by single-crystal X-ray diffraction. Although the crystallization conditions contained the final 148 C-terminal residues of SAS1B, the Fab was observed to crystallize in complex with a 15-residue fragment corresponding to one of only two elements of secondary structure that are predicted to be ordered within the C-terminal region of SAS1B. The antigen forms an amphipathic α-helix that binds the 7H2.2 combining site via hydrophilic residues in an epitope that spans the length of the antigen α-helix, with only two CH-π interactions observed along the edge of the interface between the antibody and antigen. Interestingly, the paratope contains two residues mutated away from the germline (YL32F and YH58R), as well as a ProH96-ThrH97-AspH98-AspH99 insertion within heavy chain CDR3. The intact 7H2.2 antibody exhibits high affinity for the SAS1B antigen, with 1:1 binding and nanomolar affinity for both the SAS1B C-terminal construct used for crystallization (3.38 ± 0.59 nM) and a 15-amino-acid synthetic peptide construct corresponding to the helical antigen observed within the crystal structure (1.60 ± 0.31 nM). The SAS1B-antibody structure provides the first structural insight into any portion of the subdomain architecture of the C-terminal region of the novel cancer-oocyte tumor surface neoantigen SAS1B and provides a basis for the targeted use of SAS1B.
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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 | 0.000 |
| 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".