Figure 5. Lipid metabolism involving phosphatidic acid (PA). The expression of a few key enzymes (shown in the figure) involved in the
direct metabolism of PA are affected in the
rd3 retina. CDS1 (CDP-diacylglycerol (DAG) synthase) is an enzyme that condenses PA with CTP to produce CDP-DAG, an essential
step in generating phosphatidylinositol (PI). The lipid biosynthetic enzyme AGPAT2 (1-acyl-sn-glycerol 3-phosphate O-acyltransferase
2) converts lyso(PA) into PA, which is needed to produce lipids important for cell membranes and chemical signaling within
cells. Lyso(PA) is generated by ENPP2 (ectonucleotide pyrophosphatase/phosphodiesterase 2). PPAP2c (phosphatidic acid phosphohydrolase
type 2c) catalyzes the conversion of PA to DAG. Figure is adapted from Raghu et al. [
46].