Cysteine and methionine metabolism - Homo sapiens (human)

Curator(s): Joe Strothman

Cysteine and methionine are sulfur-containing amino acids. Cysteine is synthesized from serine through different pathways in different organism groups. In bacteria and plants, cysteine is converted from serine (via acetylserine) by transfer of hydrogen sulfide. In animals, methionine-derived homocysteine is used as sulfur source and its condensation product with serine (cystathionine) is converted to cysteine. Cysteine is metabolized to pyruvate in multiple routes. Methionine is an essential amino acid, which animals cannot synthesize. In bacteria and plants, methionine is synthesized from aspartate. S-Adenosylmethionine (SAM), synthesized from methionine and ATP, is a methyl group donor in many important transfer reactions including DNA methylation for regulation of gene expression. SAM may also be used to regenerate methionine in the methionine salvage pathway.    
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Cysteine and methionine metabolism - Homo sapiens (human) cluster_node111 !meth node1 L-Serine node3 node1->node3 node66 node1->node66 node2 node2->node1 node5 O-Acetyl -L-serine node2->node5 node4 2-Aminoacrylate node3->node4 node19 L-Cysteate node4->node19 node6 node5->node6 node7 node5->node7 node8 node5->node8 node9 S-Sulfo -L-cysteine node6->node9 node15 L-Cysteine node6->node15 node7->node15 Homocysteine node7->Homocysteine node8->node15 Sulfide Sulfide->node6 Sulfide->node8 node10 node10->node9 node16 L-Cystine node10->node16 Sulfate node10->Sulfate Glutathione node10->Glutathione node17 S-Glutathionyl -L-cysteine node10->node17 node11 node11->node15 node12 node12->node15 node12->node16 node13 node13->node15 node13->Glutathione node13->node17 node14 node14->node19 node15->node14 node31 node15->node31 node32 node15->node32 Glutathione metabolism node15->Glutathione metabolism Pantothenate and CoA biosynthesis node15->Pantothenate and CoA biosynthesis node16->node11 node28 node16->node28 node29 node16->node29 Thiocysteine node18 O-Phospho -L-serine node18->node8 Taurine and hypotaurine metabolism node19->Taurine and hypotaurine metabolism node27 node19->node27 node20 node20->node15 node20->node19 node21 3-Sulfo -pyruvate node20->node21 node37 3-Mercapto -pyruvate node20->node37 node40 3-Sulfino -pyruvate node20->node40 node22 node22->node21 node23 3-Sulfo -acetate node22->node23 node24 node23->node24 Bisulfite node24->Bisulfite Pyruvate node24->Pyruvate node25 Pyruvate metabolism - Homo sapiens Pyruvate->node25 node26 Glycine, serine and threonine metabolism node26->node1 Propanoate metabolism node27->Bisulfite node27->Pyruvate node28->node15 node28->Thiocysteine node28->Pyruvate node28->Homocysteine node29->node15 node29->Thiocysteine node29->Pyruvate node45 2-Oxobutanoate node29->node45 node51 L-Cystathionine node29->node51 node30 node30->node15 node30->node37 node36 D-Cysteine node31->node36 node41 L-Cysteine -sulfinate node32->node41 node33 node38 3-Mercaptolactate node33->node38 node34 node34->Pyruvate node35 node35->Pyruvate node39 Thio-sulfate node35->node39 node36->node34 node37->node33 node37->node35 Sulfur metabolism node39->Sulfur metabolism Sulfite Sulfite->node35 Sulfite->Sulfur metabolism node40->Pyruvate node40->Sulfite node41->node20 node41->Taurine and hypotaurine metabolism node43 1.4.1.- node41->node43 node44 node41->node44 Sulfur dioxide node42 L-Alanine node43->node40 node44->Sulfur dioxide node44->node42 node45->Propanoate metabolism node46 node46->node45 node46->node51 node46->Homocysteine node47 O-Succinyl -L-homoserine node47->node46 node58 2.5.1.- node47->node58 node48 node48->node47 node49 L-Homoserine node49->node48 node50 node49->node50 node63 O-Acetyl -L-homoserine node50->node63 node51->node28 node52 L-Aspartate node53 node52->node53 node54 L-4 -Aspartyl-phosphate node53->node54 node55 node54->node55 node56 L-Aspartate -4-semialdehyde node55->node56 node57 node57->node49 node57->node56 node58->Homocysteine node59 node59->Homocysteine node60 node62 S-D -Ribosyl-L -homocysteine node60->node62 node101 S-Methyl -5-thio -D-ribose node60->node101 node61 node61->Homocysteine node62->node61 node63->node7 node63->node46 node64 S-Adenosyl -L-homocysteine node64->node59 node64->node60 node65 node65->node64 Homocysteine->node66 node87 Homocysteine->node87 node88 Homocysteine->node88 node89 Homocysteine->node89 node90 Homocysteine->node90 node66->node51 Aspartate metabolism Aspartate metabolism->node52 Homocystine node67 node67->Homocysteine node67->Homocystine node68 L-Methionine S -oxide node70 node68->node70 node71 node68->node71 node69 N-Formyl -L-methionine node73 L-Methionine node70->node73 node71->node73 node72 node72->node69 node72->node73 node74 node73->node74 node75 node73->node75 node80 node73->node80 node81 node73->node81 node76 Aminoacyl -L -methyonine node74->node76 Methanethiol node75->Methanethiol node77 node77->node73 node78 node78->node73 MtnE MtnE->node73 node79 4-Methylthio -2-oxobutanoate node79->node77 node79->node78 node79->MtnE node80->node79 node86 S-Adenosyl -L-methionine node81->node86 node82 3-Methylthio -propionate node83 node83->node82 node84 node84->node79 node85 1,2 -Dihdroxy -3-keto -5-methyl -thiopentene node85->node83 node85->node84 node86->node65 node92 node86->node92 node94 node86->node94 node87->node73 node88->node73 node89->node73 node90->node73 node91 1-Aminocyclopropane -1-carboxylate node93 node91->node93 Ethylene node92->node91 node98 S-Methyl -5-thioadenosine node92->node98 node93->Ethylene node95 S-Adenosyl -methioninamine node94->node95 node96 node95->node96 node97 node95->node97 node96->node98 node97->node98 node98->node60 node99 node98->node99 node103 node98->node103 node99->node101 node100 node102 S-Methyl -5-thio -D-ribose 1 -phosphate node100->node102 node101->node100 node103->node102 node104 1 node105 node106 S-Methyl -5-thio -D-ribulose 1 -phosphate node105->node106 node107 node106->node107 node108 2,3 -Diketo -5-methyl -thiopentyl-1 -phosphate node107->node108 node109 node108->node109 node109->node85 node110 2-Hydroxy -3-keto -5-methylthiopentenyl -1-phosphate node109->node110 node110->node109 Sulfur metabolism->Homocysteine node102->node104 node102->node105 Methionine salvage print "