Relationship between Amphipathic β Structures in the β<sub>1</sub> Domain of Apolipoprotein B and the Properties of the Secreted Lipoprotein Particles in McA-RH7777 Cells
Bibliographic record
Abstract
Our previous studies demonstrated that the first 1000 amino acid residues (the βα 1 domain) of human apolipoprotein (apo) B-100, termed apoB:1000, are required for the initiation of lipoprotein assembly and the formation of a monodisperse stable phospholipid (PL)-rich particle. The objectives of this study were (a) to assess the effects on the properties of apoB truncates undergoing sequential inclusion of the amphipathic β strands in the 700 N-terminal residues of the β 1 domain of apoB-100 and (b) to identify the subdomain in the β 1 domain that is required for the formation of a microsomal triglyceride transfer protein (MTP)-dependent triacylglycerol (TAG)-rich apoB-containing particle. Characterization of particles secreted by stable transformants of McA-RH7777 cells demonstrated the following. (1) The presence of amphipathic β strands in the 200 N-terminal residues of the β 1 domain resulted in the secretion of apoB truncates (apoB:1050 to apoB:1200) as both lipidated and lipid-poor particles. (2) Inclusion of residues 300–700 of the β 1 domain led to the secretion of apoB:1300, apoB:1400, apoB:1500, and apoB:1700 predominantly as lipidated particles. (3) Particles containing residues 1050–1500 were all rich in PL. (4) There was a marked increase in the lipid loading capacity and TAG content of apoB:1700-containing particles. (5) Only the level of secretion of apoB:1700 was markedly diminished by MTP inhibitor BMS-197636. These results suggest that apoB:1700 marks the threshold for the formation of a TAG-rich particle and support the concept that MTP participates in apoB assembly and secretion at the stage where particles undergo a transition from PL-rich to TAG-rich.
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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) | 0.000 | 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) | 0.001 | 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 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".