Figure 1.

Mitochondrial glycine is used to synthesize heme and produce one-carbon units. (A) Heme biosynthesis pathway. (B) Mitochondrial glycine can be used to synthesize heme or catabolized by the GCV into nitrogen and one-carbon units. Hem25, the yeast homolog of human SLC25A38, is a mitochondrial glycine importer, and Lpd1 is a subunit of the yeast GCV. ALAS, aminolevulinic acid synthase; ALAD, aminolevulinic acid dehydratase; PBGD, porphobilinogen deaminase; UROS, uropoporphyrinogen III synthase; UROD, uroporphyrinogen III decarboxylase; CPOX, coproporphyrinogen oxidase; PPO, protoporphyrinogen oxidase; FECH, ferrochelatase; GCV, glycine cleavage complex.