id: Pfam:PF04313
pfam_id: PF04313
name: Type I restriction enzyme R protein N terminus (HSDR_N)
short_name: HSDR_N
seed_status: EX_DUF
characterization_status: UNSCORED
curation_status: SEEDED
source_url: https://www.ebi.ac.uk/interpro/api/entry/pfam/PF04313
counters:
  proteins: 14720
  matches: 14727
  proteomes: 9564
  taxa: 15110
  structures: 11
  alphafold_models: 9590
  domain_architectures: 90
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:IPR007409
description: 'This family consists of a number of N terminal regions found in type I restriction enzyme
  R (HSDR) proteins. Restriction and modification (R/M) systems are found in a wide variety of prokaryotes
  and are thought to protect the host bacterium from the uptake of foreign DNA [[cite:PUB00019721]]. Type
  I restriction and modification systems are encoded by three genes: hsdR, hsdM, and hsdS. The three polypeptides,
  HsdR, HsdM, and HsdS, often assemble to give an enzyme (R2M2S1) that modifies hemimethylated DNA and
  restricts unmethylated DNA [[cite:PUB00019722]].'