18.104.22.168, MAT1A, 22.214.171.124, 126.96.36.199, DNMT1, 188.8.131.52, 184.108.40.206, DNMT3A, MTR, 220.127.116.11, FMT, L-serine, SAHH, N-Formyl-(L)- methionine*(tRNA), (L)-Cystathionine, 18.104.22.168, SAHH3, BHMT2, 2-Oxobutanoic acid, L-Homocysteine, CBS, (L)-Methionine, DNMT3B, MARS, MAT2A, CTH, 22.214.171.124, (L)-Methionine*(tRNA), S-Adenosyl-L- methionine, BHMT, 126.96.36.199, S-Adenosyl-L- homocysteine, (L)-Cysteine , SAHH2
The first step in (L)-Methionine metabolism, the synthesis of S-Adenosyl-(L)-methionine, is catalyzed by the Methionine adenosyltransferase I, alpha ( MAT1A ) , ,  and Methionine adenosyltransferase II, alpha ( MAT2A ) , , , , .
S-Adenosyl-(L)-methionine (AdoMet) is the primary methyl group donor in virtually all mammalian systems. DNA (cytosine-5-)-methyltransferase 1 ( D nmt 1 ) , , DNA (cytosine-5-)-methyltransferase 3 alpha ( DNMT3A )  and DNA (cytosine-5-)-methyltransferase 3 beta ( DNMT3B )  naturally catalyze the transfer of the activated methyl group from AdoMet to C5 atom of DNA cytosine with formation of S-Adenosyl-(L)-homocysteine (AdoHcy).
S-adenosylhomocysteine hydrolase ( SAHH ) , , , S-adenosylhomocysteine hydrolase-like 1 ( SAHH2 )  and S-Adenosylhomocysteine hydrolase-like 2 ( SAHH3 )  catalyze the hydrolysis of AdoHcy to adenosine and (L)-Homocysteine. In turn, Cystathionine beta-synthase ( CBS ) catalyzes the condensation of (L)-Serine and (L)-Homocysteine to form (L)-Cystathionine , . Cystathionase (cystathionine gamma-lyase) ( CTH ) catalyzes the second step in the reverse trans-sulfuration pathway (the cleavage of the (L)-Cystathionine C-gamma-S bond) yielding (L)-Cysteine, 2-Oxobutanoic acid, and ammonia .
(L)-Methionine, as another amino acid involved in protein biosynthesis, that forms aminoacyl-tRNA conjugated with corresponding tRNA by Methionyl-tRNA synthetase ( MARS) , . Mitochondrial (L)-Methionine*(tRNA) then undergoes formylation to N-Formyl-(L)-methionine*(tRNA) by Mitochondrial methionyl-tRNA formyltransferase ( FMT) .