Evidence that remodeling of the fatty acids of phosphatidylcholine is regulated in isolated rat hepatocytes and involves both the sn-1 and sn-2 positions.
The remodeling of the fatty acyl moieties of phosphatidylcholine (PC) has been studied in choline-deficient and choline-supplemented hepatocytes prepared from a choline-deficient rat. Choline-deficient hepatocytes were prelabeled with [Me-3H]choline for 30 min and subsequently incubated for up to 12 h in the presence or absence of choline. Analysis of the molecular species of PC from choline-deficient cells showed that, at the end of the pulse, approx. 75% of the label was incorporated into palmitate-containing species and only approx. 16% of the labeled species contained stearate. During the chase period there was a redistribution of label and after 12 h approx. 56% of the total radioactivity was associated with palmitate containing species and 37% was recovered in stearate-containing species. A similar distribution of radioactivity was observed in choline-supplemented cells. Measurement of the specific radioactivity of the major molecular species of PC was consistent with a precursor-product relationship between palmitate-containing species and stearate-containing species with arachidonate or linoleate on the sn-2 position. A model is presented which takes into account remodeling of both the sn-1 and sn-2 positions of PC.
Tijburg
L B
LB
Lipid and Lipoprotein Research Group, University of Alberta, Edmonton, Canada.
Samborski
R W
RW
Vance
D E
DE
D000818:Animals; D002458:Cell Fractionation; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism; D002796:Choline Deficiency / Q000378:metabolism; D003470:Culture Media; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D003470:Culture Media; D005227:Fatty Acids; D010713:Phosphatidylcholines; D002794:Choline