Figure 3.

L-Serine Biosynthesis Pathway

De novo biosynthesis of serine is crucial to provide the organism with sufficient levels of this amino acid. The first and limiting step of this pathway is the conversion of 3-phosphoglycerate to 3-phosphohydroxypiruvate by PHGDH (encoded by PHGDH). This is followed by the conversion of 3-phosphohydroxypiruvate to O-phosphoserine by PSAT (encoded by PSAT1). This reaction is accompanied by the transformation of glutamate to α-ketoglutarate and requires the presence of pyridoxal phosphate (PLP). The final step in serine biosynthesis is catalyzed by PSPH (encoded by PSPH), which gives rise to L-serine, the final product of this pathway.