Aliphatic glucosinolates’ side chain is methionine derived which is synthesized by the formation of cysteine from 3-PG4 with serine as an intermediate. Within this pathway, the intermediate methionine can allosterically regulate the enzyme PGDH which controls the entry point to the phosphorylated pathway of serine biosynthesis. Methionine also produces S-adenosylmethionine which serves as precursor to both ethylene and polyamines biosynthesis. Methionine gives rise to various glucosinolates, of which some have been observed to be catabolized to cysteine in low sulfur concentrations.