id: Pfam:PF01837
pfam_id: PF01837
name: Homocysteine biosynthesis enzyme, sulfur-incorporation
short_name: HcyBio
seed_status: EX_DUF
characterization_status: UNSCORED
curation_status: SEEDED
source_url: https://www.ebi.ac.uk/interpro/api/entry/pfam/PF01837
counters:
  proteins: 825
  matches: 827
  proteomes: 684
  taxa: 1663
  structures: 0
  alphafold_models: 656
  domain_architectures: 8
provenance:
  snapshot_id: interpro-pfam-duf-2026-10-10
  path: data/worklists/interpro-pfam-duf-2026-10-10.json
  sha256: 17fb625876c9326ed284263a47bcd84e0d7844a31c040dc06cd2260c36f1c383
  generated_at: '2026-10-10T07:44:21.614711Z'
  source_url: https://www.ebi.ac.uk/interpro/api/entry/pfam/
interpro_id: InterPro:IPR002708
description: This presumed domain is about is about 360 residues long. The function of this domain is
  not clear. It is found at N terminus in some proteins that have two C-terminal cystathionine beta-synthase
  (CBS) domains, such as MJ0100 from Methanocaldococcus jannaschii. This domain can also be found in proteins
  that contain two C-terminal inserted Fe4S domains [[cite:PUB00093781]]. In Methanocaldococcus jannaschii,
  MJ0100 and its ortholog MA1821 from Methanosarcina acetivorans are involved in Hcy (homocysteine) biosynthesis.
  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]] .