FIG. 3.

General scheme of transsulfuration, cysteine biosynthesis, and sulfur amino acid degradation. The schematic diagram shows all pathways present in bacteria. Open arrows with thin dotted lines depict pathways present in mammals; arrows with thick dotted lines represent pathways present in both E. histolytica and T. vaginalis; and arrows with thick unbroken lines or thick broken lines represent pathways present only in E. histolytica or T. vaginalis, respectively. CBS, cystathionine β-synthase; CBL, cystathionine β-lyase.