A cyclic series of interconversions involving S-methyl-L-methionine, S-adenosyl-L-homocysteine, S-adenosyl-L-methionine, L-homocysteine, and L-methionine. Converts the methionine group of adenosylmethionine back to free methionine, and may serve regulate the cellular adenosylmethionine level.
S-methylmethionine cycle