TY - JOUR
T1 - Triacylglycerol turnover in Tetrahymena pyriformis relation to phospholipid synthesis
AU - Borowitz, M. J.
AU - Blum, J. J.
N1 - Funding Information:
This work was supported by NIH Grant 5 ROl HD01269. We are grateful to Dr. Robert M. Bell of Duke University for many helpful suggestions.
PY - 1976/1/22
Y1 - 1976/1/22
N2 - The metabolic function of triaclyglycerol in Tetrahymena pyriformis was investigated by prelabeling endogenous lipid with a 14C-labeled short chain fatty acid, and then following the disappearance of radioactivity from triacylglycerol and its appearance in other products. In 90 min, up to 85% of the label in triacylglycerol turns over, and although some radioactivity appears in CO2 and glycogen, most of the label appears in phospholipid. Starvation of the cells, as well as resuspension in enriched medium or provision of acetate all block triacylglycerol breakdown, while supplementation of the medium with pyruvate does not. Prelabeling lipid with [3H]glycerol shows that some of the transfer of material from triacylglycerol to phospholipid involves transfer of the glycerol backbone, although transfer of triacylglycerol fatty acids directly to phospholipid probably also occurs. In addition, the catabolism of triacylglycerol occurs by a "last-in-first-out" mechanism, indicating some form of compartmentation of triacylglycerol in this cell. The results demonstrate an important metabolic interrelationship between triacylglycerol catabolism and phospholipid synthesis and raise the question, in this cell at least, of the validity of considering triacylglycerol only as a fuel storage form.
AB - The metabolic function of triaclyglycerol in Tetrahymena pyriformis was investigated by prelabeling endogenous lipid with a 14C-labeled short chain fatty acid, and then following the disappearance of radioactivity from triacylglycerol and its appearance in other products. In 90 min, up to 85% of the label in triacylglycerol turns over, and although some radioactivity appears in CO2 and glycogen, most of the label appears in phospholipid. Starvation of the cells, as well as resuspension in enriched medium or provision of acetate all block triacylglycerol breakdown, while supplementation of the medium with pyruvate does not. Prelabeling lipid with [3H]glycerol shows that some of the transfer of material from triacylglycerol to phospholipid involves transfer of the glycerol backbone, although transfer of triacylglycerol fatty acids directly to phospholipid probably also occurs. In addition, the catabolism of triacylglycerol occurs by a "last-in-first-out" mechanism, indicating some form of compartmentation of triacylglycerol in this cell. The results demonstrate an important metabolic interrelationship between triacylglycerol catabolism and phospholipid synthesis and raise the question, in this cell at least, of the validity of considering triacylglycerol only as a fuel storage form.
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U2 - 10.1016/0005-2760(76)90056-4
DO - 10.1016/0005-2760(76)90056-4
M3 - Article
C2 - 814931
AN - SCOPUS:0016898101
SN - 0005-2760
VL - 424
SP - 114
EP - 124
JO - Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
JF - Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
IS - 1
ER -