id: Pfam:PF09170
pfam_id: PF09170
name: CST, complex subunit STN1, C terminal
short_name: STN1_2
seed_status: EX_DUF
characterization_status: UNSCORED
curation_status: SEEDED
source_url: https://www.ebi.ac.uk/interpro/api/entry/pfam/PF09170
counters:
  proteins: 1178
  matches: 1210
  proteomes: 755
  taxa: 2397
  structures: 8
  alphafold_models: 1016
  domain_architectures: 13
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:IPR015253
description: STN1 is a component of the CST complex, a complex that binds to single-stranded DNA and is
  required for protecting telomeres from DNA degradation. The CST complex binds single-stranded DNA with
  high affinity in a sequence-independent manner, while isolated subunits bind DNA with low affinity on
  their own. In addition to telomere protection, the CST complex probably has a more general role in DNA
  metabolism at non-telomeric sites. This entry represents the C-terminal region of Stn1 which has two
  winged helix-turn-helix (wHTH) motifs, wHTH1 and wHTH2 [[cite:PUB00053885],[cite:PUB00097419]]. wHTH1
  is structurally similar to that in RPA32 with a large insertion between helices alpha2 and alpha3, unique
  to Stn1, that may allow interaction with a different set of proteins that function at telomeres such
  as Ctc1 [[cite:PUB00097419]]. wHTH2 is most similar to the DNA-binding wHTH motifs of the pur operon
  repressor and RepE replication initiator, but it does not bind double-stranded DNA [[cite:PUB00057805]].