Fig. 1

Pathways involved in phospholipid synthesis. Synthesis of PE and PC occurs through two independent branches of the Kennedy pathway. The CDPethanolamine pathway (light green) produces PE from ethanolamine and DAG, whereas the CDP-choline pathway (light blue) produces PC from choline and DAG. The liver PE could be methylated to PC by PEMT. PC and PE are metabolized to PS by PSS1 and PSS2, respectively. The mitochondria can produce PE from PS by PISD. The CDP-DAG pathway produces PI; SM is produced from ceramide (Cer) and PCho.