Figure 5. The Regulation of de novo Purine Biosynthesis and Purinosome Formation.

(A) Pathway activation and/or purinosome formation has been associated with signaling through the GPCR, MAPK, and PI3K/AKT signaling pathways. Downstream of AKT is mTOR, whose activity assists in the colocalization of purinosomes with mitochondria. Dashed lines suggest an association or correlation, whereas solid lines represent a direct interaction or consequence. (B) The phosphorylation sites identified on PFAS/FGAMS as determined our recent post-translational modification study (Liu et al., 2019) and other global phosphoproteomic studies recorded on PhosphoSite. Solid red circles and white circles represent those phosphorylation events identified under purine supplemented and purine-depleted growth conditions, respectively. Red stripped circles were either present in both conditions or the site preference is unknown. Kinase predictions are a combination from ScanSite and/or Liu et al., 2019.