The hemicholinium‐3 sensitive high affinity choline transporter is internalized by clathrin‐mediated endocytosis and is present in endosomes and synaptic vesicles
Bibliographic record
Abstract
Synthesis of acetylcholine depends on the plasma membrane uptake of choline by a high affinity choline transporter (CHT1). Choline uptake is regulated by nerve impulses and trafficking of an intracellular pool of CHT1 to the plasma membrane may be important for this regulation. We have generated a hemagglutinin (HA) epitope tagged CHT1 to investigate the organelles involved with intracellular trafficking of this protein. Expression of CHT1-HA in HEK 293 cells establishes Na+-dependent, hemicholinium-3 sensitive high-affinity choline transport activity. Confocal microscopy reveals that CHT1-HA is found predominantly in intracellular organelles in three different cell lines. Importantly, CHT1-HA seems to be continuously cycling between the plasma membrane and endocytic organelles via a constitutive clathrin-mediated endocytic pathway. In a neuronal cell line, CHT1-HA colocalizes with the early endocytic marker green fluorescent protein (GFP)-Rab 5 and with two markers of synaptic-like vesicles, VAMP-myc and GFP-VAChT, suggesting that in cultured cells CHT1 is present mainly in organelles of endocytic origin. Subcellular fractionation and immunoisolation of organelles from rat brain indicate that CHT1 is present in synaptic vesicles. We propose that intracellular CHT1 can be recruited during stimulation to increase choline uptake in nerve terminals.
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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".