The main route for glycine biosynthesis is from L-threonine and occurs in the mitochondrion. Alternatively, glycine can be produced in the cytosol from L-serine by Shmt or via transamination of L-alanine and glyoxylate by Agxt; however, the contribution of these two pathways to the L-glycine pool is likely small. Besides its role in protein synthesis, glycine acts as a neurotransmitter. It is also a precursor for the synthesis of glutathione, heme and purine nucleotides, and is involved in the tetrahydrofolate (one-carbon) metabolism and tubulin glycylation. (Adapted from PMID: 23615880.)