Figure 1.

Biosynthesis of cysteine and subcellular localization of SAT and OASTL isoforms in Arabidopsis thaliana. Primary sulfur assimilation and reduction takes place in plastids where is reduced to sulfide. The sulfide is incorporated to the carbon skeleton of OAS within the plastid, or diffuses to the cytosol and the mitochondria, to form the cysteine molecule. For each compartment, the SAT and OASTL isoforms involved in the catalysis are shown (bold red font represent the major isoform). The β-cyanoalanine synthase isoforms are also shown in the diagram.