L-serine is synthesized de novo in the cytosol from the glycolytic intermediate 3-phosphoglycerate. Alternatively, it can be produced in the mitochondrion from glycine by serine hydroxymethyl transferase Shmt; however, this is likely a minor route. Besides its role in protein synthesis, L-serine is a precursor for the production of neurotransmitter D-serine, the amino acids glycine and L-cysteine, and the lipid phosphatidylserine. (Adapted from PMID:35565953 and FBrf0239397.)