<p>(A) Phospholipid synthesis in the methylation pathway is compartmentalized between ER and mitochondria. PS synthesized in the ER is transferred to mitochondria for conversion into PE and transported back to the ER for conversion to PC. The Kennedy pathway synthesizes PE and PC from ethanolamine (etn) and choline (cho) independent of lipid transfer between ER and mitochondria. (B) Yeast growth assays for the indicated mutants in the absence (nil) or presence of ethanolamine (+ etn) or choline (+ cho). (C) Results of SGA screen for <i>CHO2</i> in the absence (–) and presence (+) of choline. Genetic interactions are plotted as the log2 of the ratio of growth of single versus double mutants with <i>Δcho2</i> in the absence and presence of choline. Interactions rescued by choline (green triangles) predominately clustered on the x axis, whereas interactions not rescued (red squares) were present on the diagonal. (D) Enrichment of functional groups for the genes that showed interactions and were rescued by choline in (C). Fold enrichment represents the frequency of a given term in our dataset relative to the frequency of that term in the whole genome.</p
