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MJ0100 CBS domains bind S-adenosyl-l-methionine (SAM) and 5'-methylthioadenosine (MTA), which induce a conformational change consistent with regulatory function. Another protein in the homocysteine biosynthesis pathway, MJ0099 and its ortholog MA1822, is involved in the reduction of the disulfide formed in MJ0100/MA1821 during the conversion of Asa (aspartate semialdehyde) to Hcy [[cite:PUB00078766],[cite:PUB00093781]]. The DUF39-CBS and DUF39-ferredoxin architectures repeatedly occur together in the genomes of methanogenic Archaea, suggesting they may be of diverged function. This is consistent with a phylogenetic reconstruction of the DUF39 family, which clearly distinguishes the CBS-associated and ferredoxin-associated DUF39s [[cite:PUB00078766]] .","domain_architectures":8,"interpro_id":"IPR002708","known_evidence_count":null,"matches":827,"name":"Homocysteine biosynthesis enzyme, sulfur-incorporation","partial_evidence_count":null,"pfam_id":"PF01837","proteins":825,"proteomes":684,"short_name":"HcyBio","source_url":"https://www.ebi.ac.uk/interpro/api/entry/pfam/PF01837","structures":0,"taxa":1663,"unknown_status":"EX_DUF"},"inputs":{"cross_mech":"cross-mech-duf-examples-2026-10-10","members":"pfam-uniprot-uniref90-2026-10-07","protein_examples":"duf-protein-examples-2026-10-13","worklist":"interpro-pfam-duf-2026-10-10"},"members":[],"metadata":{"curation_status":"SEEDED","local_source":"source/data/families/PF01837.yaml","record":{"characterization_status":"UNSCORED","counters":{"alphafold_models":656,"domain_architectures":8,"matches":827,"proteins":825,"proteomes":684,"structures":0,"taxa":1663},"curation_status":"SEEDED","description":"This presumed domain is about is about 360 residues long. 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The DUF39-CBS and DUF39-ferredoxin architectures repeatedly occur together in the genomes of methanogenic Archaea, suggesting they may be of diverged function. This is consistent with a phylogenetic reconstruction of the DUF39 family, which clearly distinguishes the CBS-associated and ferredoxin-associated DUF39s [[cite:PUB00078766]] .","id":"Pfam:PF01837","interpro_id":"InterPro:IPR002708","name":"Homocysteine biosynthesis enzyme, 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