id: Pfam:PF03937
pfam_id: PF03937
name: Flavinator of succinate dehydrogenase
short_name: Sdh5
seed_status: EX_DUF
characterization_status: UNSCORED
curation_status: SEEDED
source_url: https://www.ebi.ac.uk/interpro/api/entry/pfam/PF03937
counters:
  proteins: 10651
  matches: 10656
  proteomes: 9808
  taxa: 17438
  structures: 9
  alphafold_models: 7861
  domain_architectures: 66
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:IPR005631
description: This family includes the highly conserved mitochondrial and bacterial proteins Sdh5/SDHAF2/SdhE.
  Both yeast and human Sdh5/SDHAF2 interact with the catalytic subunit of the succinate dehydrogenase
  (SDH) complex, a component of both the electron transport chain and the tricarboxylic acid cycle. Sdh5
  is required for SDH-dependent respiration and for Sdh1 flavination (incorporation of the flavin adenine
  dinucleotide cofactor). Mutational inactivation of Sdh5 confers tumor susceptibility in humans [[cite:PUB00066692]].
  Bacterial homologues of Sdh5, termed SdhE, are functionally conserved being required for the flavinylation
  of SdhA and succinate dehydrogenase activity. Like Sdh5, SdhE interacts with SdhA. Furthermore, SdhE
  was characterised as a FAD co-factor chaperone that directly binds FAD to facilitate the flavinylation
  of SdhA. Phylogenetic analysis demonstrates that SdhE/Sdh5 proteins evolved only once in an ancestral
  alpha-proteobacteria prior to the evolution of the mitochondria and now remain in subsequent descendants
  including eukaryotic mitochondria and the alpha, beta and gamma proteobacteria [[cite:PUB00066693]].
  This family was previously annotated in Pfam as being a divergent TPR repeat but structural evidence
  has indicated this is not true. The E. coli protein, YgfY also acts as the antitoxin to the membrane-bound
  toxin family Cpta, [pfam:PF13166], whose E. coli member YgfX, expressed from the same operon as YgfY
  [[cite:PUB00075551]].