part_of methionine cycle/metabolic pathway PW:0000048 SMP:00033 Those metabolic reactions involved in the synthesis (remethylation), utilization and/or degradation of methionine, an essential amino acid for humans. The cycle produces S-adenosylmethionine (AdoMet), the major methyl donor for proteins, nucleic acids, lipids and other small molecules. The cycle also produces homocysteine (Hcy) which either regenerates methionine via the remethylation pathway or leads to the synthesis of cysteine and derivatives via the transsulfuration pathway. Homocysteine and folate metabolic pathways are intimately related to the methionine cycle. pathway hydrophobic amino acid metabolic pathway S-adenosylmethionine homeostasis pathway