Identification of an Amino Acid Residue Critical for Plasma Membrane Localization of ATP-Binding Cassette Transporter G1—Brief Report
Bibliographic record
Abstract
OBJECTIVE: ATP-binding cassette transporter G1 (ABCG1) mediates cholesterol efflux to lipidated lipoproteins. Conflicting data about cellular localization of ABCG1 and its effect on cholesterol efflux have been reported. Here, we investigated the underlying mechanisms for these different observations. APPROACH AND RESULTS: Confocal microscopy and biotinylation were used to assess cell surface localization of ABCG1. We found that mouse ABCG1 (mABCG1) used in one previous study has a substitution of Leu to Pro at position 550 (mG1-L550P). When the corresponding Leu at position 562 in human ABCG1 (hABCG1) was mutated to Pro (hG1-L562P), the mutant hABCG1, like mG1-L550P, mainly resided intracellularly, whereas wild-type mABCG1 and hABCG1 were localized on the plasma membrane. However, replacement of this Leu with Pro had no significant effect on mABCG1- and hABCG1-mediated cholesterol efflux. CONCLUSIONS: Leu at position 550/562 in mABCG1/hABCG1 is critical for their plasma membrane localization but not for ABCG1-mediated cholesterol efflux. Our findings indicate that the substitution of Leu to Pro at position 550 in mABCG1 may contribute to the non-cell surface localization of mABCG1 observed in the previous study.
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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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".