homocysteine and cysteine interconversion

gomodel:YeastPathways_HOMOCYS-CYS-CONVERT

Homocysteine and cysteine interconversion in Saccharomyces cerevisiae S288C combines cystathionine beta-synthase and gamma-lyase activities that convert L-homocysteine to L-cysteine via L-cystathionine with cystathionine gamma-synthase and beta-lyase activities that convert L-cysteine toward L-homocysteine through the same intermediate.

Pathway type

amino acid metabolism

Organism scope

Saccharomyces cerevisiae S288C NCBITaxon:559292

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Pathway network

24 nodes · 39 asserted directed edges

Arrows show recorded subject → object relationships, not necessarily metabolic flow. Select a node for details or an arrow for evidence. Scroll, zoom or find a node to explore.

Reaction / activity
Chemical / cofactor
Protein / complex
Cell / process context
Solid arrow: mechanistic relation
Dashed arrow: membership, location or cofactor relation

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Components and activities

Declared biological components and source reaction directions
Node	Kind or role	Source direction
Saccharomyces cerevisiae S288C `NCBITaxon:559292`	taxon
water `CHEBI:15377`	small molecule
ammonia `CHEBI:16134`	small molecule
homocysteine metabolic process `GO:0050667`	biological process
pyruvate `CHEBI:15361`	small molecule
ammonium `CHEBI:28938`	small molecule
acetate `CHEBI:30089`	small molecule
L-cystathionine dizwitterion `CHEBI:58161`	small molecule
STR3 Scer `SGD:S000003152`	protein
cytosol `GO:0005829`	cellular component
O-acetyl-L-homoserine zwitterion `CHEBI:57716`	small molecule
L-serine zwitterion `CHEBI:33384`	small molecule
CYS3 Scer `SGD:S000000010`	protein
L-cysteine zwitterion `CHEBI:35235`	small molecule
2-oxobutanoate `CHEBI:16763`	lipid
CYS4 Scer `SGD:S000003387`	protein
L-homocysteine zwitterion `CHEBI:58199`	small molecule
STR2 Scer `SGD:S000003891`	protein
cytoplasm `GO:0005737`	cellular component
nucleus `GO:0005634`	cellular component
pyridoxal 5'-phosphate(2-) `CHEBI:597326`	cofactor
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	molecular activity
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	molecular activity
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	molecular activity
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	molecular activity

Mechanistic edges

Mechanistic edges and their cited evidence
Subject	Predicate and description	Object	Evidence
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	has_input	water `CHEBI:15377`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN RO:0002233 gomodel:CHEBI_15377_CYSTAGLY-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/0; endpoint types: /individuals/14/type; /individuals/1/type`
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	has_output	ammonia `CHEBI:16134`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN RO:0002234 gomodel:CHEBI_16134_CYSTAGLY-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/1; endpoint types: /individuals/14/type; /individuals/4/type`
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	part_of	homocysteine metabolic process `GO:0050667`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN BFO:0000050 gomodel:YeastPathways_HOMOCYS-CYS-CONVERT/YeastPathways_HOMOCYS-CYS-CONVERT. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/2; endpoint types: /individuals/14/type; /individuals/52/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	has_output	pyruvate `CHEBI:15361`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN RO:0002234 gomodel:CHEBI_15361_CYSTATHIONINE-BETA-LYASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/3; endpoint types: /individuals/15/type; /individuals/0/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	has_output	ammonium `CHEBI:28938`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN RO:0002234 gomodel:CHEBI_28938_CYSTATHIONINE-BETA-LYASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/4; endpoint types: /individuals/15/type; /individuals/6/type`
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	has_output	acetate `CHEBI:30089`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 RO:0002234 gomodel:CHEBI_30089_RXN-721. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/5; endpoint types: /individuals/17/type; /individuals/7/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	has_input	L-cystathionine dizwitterion `CHEBI:58161`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN RO:0002233 gomodel:CHEBI_58161_RXN-721. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/6; endpoint types: /individuals/15/type; /individuals/12/type`
STR3 Scer `SGD:S000003152`	enables	L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN RO:0002333 gomodel:YGL184C-MONOMER_CYSTATHIONINE-BETA-LYASE-RXN_controller. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/7; endpoint types: /individuals/15/type; /individuals/19/type`
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	has_output	water `CHEBI:15377`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN RO:0002234 gomodel:CHEBI_15377_CYSTATHIONINE-BETA-SYNTHASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/8; endpoint types: /individuals/16/type; /individuals/3/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	occurs_in	cytosol `GO:0005829`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN BFO:0000066 gomodel:reaction_CYSTATHIONINE-BETA-LYASE-RXN_location_lociGO_0005829. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/9; endpoint types: /individuals/15/type; /individuals/49/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	part_of	homocysteine metabolic process `GO:0050667`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN BFO:0000050 gomodel:YeastPathways_HOMOCYS-CYS-CONVERT/YeastPathways_HOMOCYS-CYS-CONVERT. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/10; endpoint types: /individuals/15/type; /individuals/52/type`
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	has_input	O-acetyl-L-homoserine zwitterion `CHEBI:57716`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 RO:0002233 gomodel:CHEBI_57716_RXN-721. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/11; endpoint types: /individuals/17/type; /individuals/10/type`
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	occurs_in	cytosol `GO:0005829`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN BFO:0000066 gomodel:reaction_CYSTATHIONINE-BETA-SYNTHASE-RXN_location_lociGO_0005829. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/12; endpoint types: /individuals/16/type; /individuals/50/type`
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	occurs_in	cytosol `GO:0005829`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 BFO:0000066 gomodel:reaction_RXN-721_location_lociGO_0005829. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/13; endpoint types: /individuals/17/type; /individuals/51/type`
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	has_input	L-serine zwitterion `CHEBI:33384`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN RO:0002233 gomodel:CHEBI_33384_CYSTATHIONINE-BETA-SYNTHASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/14; endpoint types: /individuals/16/type; /individuals/8/type`
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	part_of	homocysteine metabolic process `GO:0050667`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 BFO:0000050 gomodel:YeastPathways_HOMOCYS-CYS-CONVERT/YeastPathways_HOMOCYS-CYS-CONVERT. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/15; endpoint types: /individuals/17/type; /individuals/52/type`
CYS3 Scer `SGD:S000000010`	enables	L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN RO:0002333 gomodel:YAL012W-MONOMER_CYSTAGLY-RXN_controller. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/16; endpoint types: /individuals/14/type; /individuals/18/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	has_input	water `CHEBI:15377`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN RO:0002233 gomodel:CHEBI_15377_CYSTATHIONINE-BETA-LYASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/17; endpoint types: /individuals/15/type; /individuals/2/type`
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	has_input	L-cysteine zwitterion `CHEBI:35235`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 RO:0002233 gomodel:CHEBI_35235_CYSTAGLY-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/18; endpoint types: /individuals/17/type; /individuals/9/type`
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	has_input	L-cystathionine dizwitterion `CHEBI:58161`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN RO:0002233 gomodel:CHEBI_58161_RXN-721. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/19; endpoint types: /individuals/14/type; /individuals/12/type`
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	has_output	2-oxobutanoate `CHEBI:16763`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN RO:0002234 gomodel:CHEBI_16763_CYSTAGLY-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/20; endpoint types: /individuals/14/type; /individuals/5/type`
CYS4 Scer `SGD:S000003387`	enables	L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN RO:0002333 gomodel:YGR155W-MONOMER_CYSTATHIONINE-BETA-SYNTHASE-RXN_controller. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/21; endpoint types: /individuals/16/type; /individuals/20/type`
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	occurs_in	cytosol `GO:0005829`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN BFO:0000066 gomodel:reaction_CYSTAGLY-RXN_location_lociGO_0005829. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/22; endpoint types: /individuals/14/type; /individuals/48/type`
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	part_of	homocysteine metabolic process `GO:0050667`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN BFO:0000050 gomodel:YeastPathways_HOMOCYS-CYS-CONVERT/YeastPathways_HOMOCYS-CYS-CONVERT. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/23; endpoint types: /individuals/16/type; /individuals/52/type`
L-cystathionine + H₂O -> L-homocysteine + pyruvate + ammonium `gomodel:CYSTATHIONINE-BETA-LYASE-RXN`	has_output	L-homocysteine zwitterion `CHEBI:58199`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-LYASE-RXN RO:0002234 gomodel:CHEBI_58199_CYSTATHIONINE-BETA-LYASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/24; endpoint types: /individuals/15/type; /individuals/13/type`
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	has_input	L-homocysteine zwitterion `CHEBI:58199`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN RO:0002233 gomodel:CHEBI_58199_CYSTATHIONINE-BETA-LYASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/25; endpoint types: /individuals/16/type; /individuals/13/type`
L-homocysteine + L-serine <=> L-cystathionine + H₂O `gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN`	has_output	L-cystathionine dizwitterion `CHEBI:58161`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTATHIONINE-BETA-SYNTHASE-RXN RO:0002234 gomodel:CHEBI_58161_CYSTATHIONINE-BETA-SYNTHASE-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/26; endpoint types: /individuals/16/type; /individuals/11/type`
STR2 Scer `SGD:S000003891`	enables Retain the native O-acetylhomoserine reaction: inspected YeastCyc STR2 lists both O-acetyl and O-succinyl reactions. UniProt P47164 lists only O-succinylhomoserine; that difference does not disprove the O-acetyl route.	L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 RO:0002333 gomodel:YJR130C-MONOMER_RXN-721_controller. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/27; endpoint types: /individuals/17/type; /individuals/21/type` SGD:S000003891 Source assertion: YeastCyc STR2 lists RXN-721: L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate, as well as O-SUCCHOMOSERLYASE-RXN with O-succinyl-L-homoserine. Source location `https://pathway.yeastgenome.org/gene?id=YJR130C&orgid=YEAST [sha256:ea882c3e1f62e6e4d44e3d5b9851f6899b2b7c69b15d38f27ee169abd20e6917] Reactions table / RXN-721 and O-SUCCHOMOSERLYASE-RXN`
L-cysteine + O-acetyl-L-homoserine -> L-cystathionine + acetate `gomodel:RXN-721`	has_output	L-cystathionine dizwitterion `CHEBI:58161`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:RXN-721 RO:0002234 gomodel:CHEBI_58161_RXN-721. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/28; endpoint types: /individuals/17/type; /individuals/12/type`
L-cystathionine + H₂O <=> 2-oxobutanoate + L-cysteine + ammonia `gomodel:CYSTAGLY-RXN`	has_output	L-cysteine zwitterion `CHEBI:35235`	gomodel:YeastPathways_HOMOCYS-CYS-CONVERT Source assertion: The model asserts gomodel:CYSTAGLY-RXN RO:0002234 gomodel:CHEBI_35235_CYSTAGLY-RXN. Source location `./YeastPathways_HOMOCYS-CYS-CONVERT.json#/facts/29; endpoint types: /individuals/14/type; /individuals/9/type`
STR3 Scer `SGD:S000003152`	located_in Physical protein location from reviewed UniProt. ECO:0000269 (PubMed:14562095)	cytoplasm `GO:0005737`	UniProtKB:P53101 Source assertion: UniProtKB:P53101 annotates location Cytoplasm (SL-0086). Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/3936/comments/0/subcellularLocations/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d` UniProtKB:P53101 Source assertion: UniProtKB:P53101 has the exact SGD cross-reference SGD:S000003152. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/3936/uniProtKBCrossReferences/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d`
STR3 Scer `SGD:S000003152`	located_in Physical protein location from reviewed UniProt. ECO:0000269 (PubMed:14562095)	nucleus `GO:0005634`	UniProtKB:P53101 Source assertion: UniProtKB:P53101 annotates location Nucleus (SL-0191). Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/3936/comments/0/subcellularLocations/1; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d` UniProtKB:P53101 Source assertion: UniProtKB:P53101 has the exact SGD cross-reference SGD:S000003152. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/3936/uniProtKBCrossReferences/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d`
CYS3 Scer `SGD:S000000010`	located_in Physical protein location from reviewed UniProt. ECO:0000269 (PubMed:14562095)	cytoplasm `GO:0005737`	UniProtKB:P31373 Source assertion: UniProtKB:P31373 annotates location Cytoplasm (SL-0086). Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/839/comments/1/subcellularLocations/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d` UniProtKB:P31373 Source assertion: UniProtKB:P31373 has the exact SGD cross-reference SGD:S000000010. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/839/uniProtKBCrossReferences/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d`
STR2 Scer `SGD:S000003891`	located_in Physical protein location from reviewed UniProt. ECO:0000269 (PubMed:14562095)	cytoplasm `GO:0005737`	UniProtKB:P47164 Source assertion: UniProtKB:P47164 annotates location Cytoplasm (SL-0086). Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/1983/comments/1/subcellularLocations/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d` UniProtKB:P47164 Source assertion: UniProtKB:P47164 has the exact SGD cross-reference SGD:S000003891. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/1983/uniProtKBCrossReferences/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d`
STR2 Scer `SGD:S000003891`	located_in Physical protein location from reviewed UniProt. ECO:0000269 (PubMed:14562095)	nucleus `GO:0005634`	UniProtKB:P47164 Source assertion: UniProtKB:P47164 annotates location Nucleus (SL-0191). Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/1983/comments/1/subcellularLocations/1; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d` UniProtKB:P47164 Source assertion: UniProtKB:P47164 has the exact SGD cross-reference SGD:S000003891. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_subcellular_location%2Ccc_function%2Ccc_caution%2Corganism_id#/results/1983/uniProtKBCrossReferences/0; sha256=95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d`
STR3 Scer `SGD:S000003152`	has_cofactor UniProtKB reviewed (Swiss-Prot) annotation. UniProt evidence: ECO:0000250	pyridoxal 5'-phosphate(2-) `CHEBI:597326`	UniProtKB:P53101 Source assertion: UniProtKB:P53101 annotates CHEBI:597326 as a cofactor of this protein. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/3936/comments/0/cofactors/0` UniProtKB:P53101 Source assertion: UniProtKB:P53101 has the exact SGD cross-reference SGD:S000003152. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/3936/uniProtKBCrossReferences/0`
CYS3 Scer `SGD:S000000010`	has_cofactor UniProtKB reviewed (Swiss-Prot) annotation. UniProt evidence: ECO:0000269 (PubMed:12715888)	pyridoxal 5'-phosphate(2-) `CHEBI:597326`	UniProtKB:P31373 Source assertion: UniProtKB:P31373 annotates CHEBI:597326 as a cofactor of this protein. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/839/comments/0/cofactors/0` UniProtKB:P31373 Source assertion: UniProtKB:P31373 has the exact SGD cross-reference SGD:S000000010. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/839/uniProtKBCrossReferences/0`
CYS4 Scer `SGD:S000003387`	has_cofactor UniProtKB reviewed (Swiss-Prot) annotation. UniProt evidence: not specified	pyridoxal 5'-phosphate(2-) `CHEBI:597326`	UniProtKB:P32582 Source assertion: UniProtKB:P32582 annotates CHEBI:597326 as a cofactor of this protein. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/958/comments/0/cofactors/0` UniProtKB:P32582 Source assertion: UniProtKB:P32582 has the exact SGD cross-reference SGD:S000003387. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/958/uniProtKBCrossReferences/0`
STR2 Scer `SGD:S000003891`	has_cofactor UniProtKB reviewed (Swiss-Prot) annotation. UniProt evidence: ECO:0000250 (UniProtKB:P32929)	pyridoxal 5'-phosphate(2-) `CHEBI:597326`	UniProtKB:P47164 Source assertion: UniProtKB:P47164 annotates CHEBI:597326 as a cofactor of this protein. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/1983/comments/0/cofactors/0` UniProtKB:P47164 Source assertion: UniProtKB:P47164 has the exact SGD cross-reference SGD:S000003891. Source location `https://rest.uniprot.org/uniprotkb/stream?query=taxonomy_id%3A559292+AND+reviewed%3Atrue&format=json&fields=accession%2Cprotein_name%2Cxref_sgd%2Ccc_cofactor%2Corganism_id%2Ccc_caution [sha256:1378282d22c5518215707964664b55946f468ba74a227a6ea1bbf27db69ddbc4] #/results/1983/uniProtKBCrossReferences/0`

References

gomodel:YeastPathways_HOMOCYS-CYS-CONVERT SGD GO-CAM homocysteine and cysteine interconversion - imported from: Saccharomyces Genome Database (source version: Pinned Noctua JSON archive; model date 2024-07-25; member ./YeastPathways_HOMOCYS-CYS-CONVERT.json)
UniProtKB:P53101 Reviewed UniProtKB P53101 location annotations (source version: UniProt release 2026_03)
UniProtKB:P31373 Reviewed UniProtKB P31373 location annotations (source version: UniProt release 2026_03)
UniProtKB:P47164 Reviewed UniProtKB P47164 location annotations (source version: UniProt release 2026_03)
SGD:S000003891 YeastCyc STR2: two annotated reactions (source version: YeastCyc 22.5; retrieved 2026-10-05)
UniProtKB:P32582 UniProtKB P32582 cofactor annotations (source version: 2026_03)

Curation history

2026-10-05T06:05:08Z Codex; review-causal-graph; Reviewed every native GO-CAM fact; preserved precise input/output, causal, location, membership and complex-part relations with traceable structured source evidence. Kept distinct generic physical instances and recorded source-scope exclusions in the cohort review ledger.
2026-10-05T06:43:56Z Codex
- EDIT — Audit causal activity compartments and preserve scoped protein location evidence
  Reviewed all 4 activity location assignments and 4 mapped physical proteins against reviewed S288C UniProt release2026_03 location/function/caution batch SHA256 95f72dcc644358c480e0e59f996cf88533558b5fa4256460a030e0a1eaf9678d. Added 5 independently supported location edges and quarantined 0 generic cytosol source assertions. Mapped physical protein locations via exact SGD cross-references; retained source ECO grades, molecular form and conditional notes. Physical protein location alone never generates activity location. Explicitly inspected functional assertions support bounded activity projections. Every original activity location and exclusion is recorded in reports/causal_graph_review/gocam-location-review.json. No independent location annotation is treated as an evidence gap, not a negative result. Cytoplasm is not narrowed to cytosol. Microsome fractions are not projected as in-vivo organelles. Semantic validation passed all85 records;4 independent source-role acceptance tests passed.
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2026-10-05T06:58:27Z claude-code
- EDIT — Document STR2 substrate authority conflict
  Retained native O-acetylhomoserine reaction after inspecting YeastCyc STR2 listing both O-acetyl and O-succinyl activities. Current UniProt single O-succinyl annotation does not disprove the native O-acetyl route. Added explicit edge qualification; pinned source and disposition in reports/causal_graph_review/gocam-assignment-conflicts.json. Schema validation and idempotent dry-run passed.
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