Enhanced N-acylation of palmitic acid in sphingomyelin of antibody-stimulated L cells.
Metabolism of sphingomyelin was stimulated in a fibroblast-like transformed cell line, L-929, when the cells were incubated with antibodies of a specific rabbit antiserum. The cells responded with an increased incorporation of [3H] palmitic acid into sphingomyelin. The stimulated uptake of palmitic acid into sphingomyelin can not be explained by simple mass increases in cellular phospholipids but probably represents a selective N-acyl group turnover. Palmitic acid composed only 7.5 percent of the acyl substituents, as assessed by gas-liquid chromatographic analysis, but [3H] palmitic acid was incorporated at a two-fold higher level into the acyl position than into the long chain base precursor (sphingosine). Since it is known that palmitic acid is the predominant fatty acid forming sphingosine, this represents a considerable selection for N-acyl group turnover. Another saturated fatty acid, stearic acid, which was over twice as abundant constituently was incorporated at a much lower rate when the cells were stimulated. Thus palmitic acid was observed to be selectively turning over in a manner suggestive of acylation-reacylation cycles observed with other classes of phospholipids.
D000215:Acylation; D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D055598:Chemical Phenomena; D002621:Chemistry; D007739:L Cells / Q000276:immunology / Q000378:metabolism; D051379:Mice; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D010743:Phospholipids / Q000096:biosynthesis; D013109:Sphingomyelins / Q000378:metabolism*
D000906:Antibodies; D010169:Palmitic Acids; D010743:Phospholipids; D013109:Sphingomyelins; D019308:Palmitic Acid