Figure 5.

Incorporation of radiolabeled methionine into choline-containing phospholipids. [l-methyl-³H]methionine was injected into the bloodstream of mice of each of the three genotypes. Plasma and organs were harvested after 1 h (A) or 24 h (B). Phospholipids were extracted and separated by thin-layer chromatography. Bands corresponding to choline-containing phospholipids (PC, lyso PC, and sphingomyelin) were scraped, and radiolabel incorporation measured, as well as total lipid phosphorous. Results are expressed as dpm per μmol choline-containing phospholipid. The mouse homozygous for the disrupted Pempt2 allele had only 4.4% the level of radiolabeled methionine incorporation into choline-containing phospholipid seen in the normal mouse after 1 h, and 4.9% the level of incorporation after 24 h.