Glycerolipid metabolism in mammalian tissues
Bibliographic record
Abstract
The biological membrane surrounds all cells and delineates intracellular compartments. Lipids form building blocks of the biological membrane, and phosphatidylcholine is the principle lipid in the mammalian membrane. In this study, phosphatidylcholine metabolism and the direct acylation of glycerol for lipid biosynthesis were investigated. The inhibition of phosphatidylcholine biosynthesis by extracellular phosphocholine was studied in human umbilical vein endothelial cells. The activities of the enzymes in the CDP-choline pathway were not altered, but the intracellular phosphocholine pool was significantly reduced. The reduction was caused by competitive inhibition of choline uptake by phosphocholine. Phosphocholine also caused a limited stimulation of arachidonate release from phosphatidylcholine, and the release was potentiated by ATP. These studies clearly demonstrate that exogenous; phosphocholine has the potential to modulate phosphatidylcholine metabolism in mammalian tissues. The acylation of glycerol-'sn'-3-phosphate is regarded as the first committed step for glycerolipid biosynthesis. The direct acylation of glycerol in mammalian tissues has not been previously demonstrated. In this study, lipid biosynthesis in myoblast and hepatocyte cells was reassessed by conducting pulse-chase experiments with [1,3-3H] glycerol. The results suggested that a portion of labeled glycerol was directly acylated to form monoacylglycerol and subsequently diacylglycerol and triacylglycerol. This pathway became prominent when the glycerol-3-phosphate pathway was attenuated and when the exogenous glycerol concentration was elevated. The present study indicates the existence of a novel lipid biosynthetic pathway that may be important during hyperglycerolemia produced in diabetes or other pathological conditions. Glycerol: acyl-CoA acyltransferase, the enzyme which directly acylates glycerol is located in the microsomal fraction of tissue homogenate. It was identified as an 18 kDa protein after purification by FPLC gel filtration, photoaffinity labeling and gel electrophoresis. The purification was confirmed by immunoprecipitation studies, and sequence analysis of the protein identified the acyltransferase as similar to myoglobin. These studies suggest that myoglobin in the pig heart may be modified and subsequently translocated to the membrane where enzyme activity is then conferred.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".