Figure 3. Purine Metabolic Cassette.

The subset of reactions within the folate metabolic pathway that have been inferred to be relevant to purine biosynthesis based on observations in the literature (see text for details). Genes (balloons) and their cognate enzymatic steps (arrows) are colored either green (beneficial to purine synthesis) or red (detrimental to purine synthesis). The MTHFD1L reaction, responsible for generating mitochondrial formate [31] and beneficial to purine synthesis, is shown in blue because it was not one of the 31 sequenced genes.