PF08975: 2H-phosphodiest

Domain of unknown function (DUF1868)

Curation status: SEEDED
Seed status: EX DUF
Characterization: UNSCORED

Grounding

PF08975: Domain of unknown function (DUF1868)
IPR015069: integrated entry for Domain of unknown function (DUF1868)

Source description

This group of 2H-phosphodiesterases comprises a single family typified by the protein mlr3352 from M.loti. Members are also present in various alpha-proteobacteria, Synechocystis, Streptococcus and Chilo iridescent virus. The presence of a member of this predominantly bacterial group in a large eukaryotic DNA virus represents a potential case of horizontal transfer from a bacterial source into a virus. Several proteins of bacterial origin have been noticed in the insect viruses (L.M.Iyer, E.V.Koonin and L.Aravind, unpublished observations and these appear to have been acquired from endo-symbiotic or parasitic bacteria that share the same host cells with the viruses. Presence of 2H proteins in the proteomes of large DNA viruses (e.g. T4 57B protein and the Fowl-pox virus FPV025) may point to some role for these proteins in regulating the viral tRNA metabolism. Each member of this family contains an internal duplication, each of which contains an HXTX motif that defines the family.

Evidence and references

Frozen description source: InterPro/Pfam API

Source descriptions and links are provenance, not independent functional validation.

Evidence counts: not scored.

Curated functional assertions

No curated functional assertions supplied.

Protein sequence examples

1 verified sequence example. FASTA

UniProt	Protein / organism	Sequence	Provenance
O55739	Uncharacterized protein 127L Invertebrate iridescent virus 6	235 aa; version 1 UniProt 2026_03	UNIPROT FETCH 1 sibling references ProteinTraitsMech: Pfam:PF08975

Pfam membership is not functional evidence. Whole-protein sequences do not establish domain boundaries. A coverage gap here is not absence from UniProt.

Sequences and metadata: UniProt Consortium, CC BY 4.0.

Domain matches

No residue-level domain match evidence is available in this build. Structure and AlphaFold counters do not supply coordinates or establish function.

Snapshot counters

proteins: 762
matches: 763
proteomes: 685
taxa: 1,467
structures: 1
alphafold models: 532
domain architectures: 5

Classification basis

name matches duf; name says unknown function; domain of unknown function; pfam previous unknown name

No scoring reasons supplied.

Related Mech records

Family	Mech	Record	Protein	Link basis
2H-phosphodiest (PF08975)	ProteinTraitsMech	2H-phosphodiesterase-like, Domain of unknown function DUF1868		trait identifier
2H-phosphodiest (PF08975)	ProteinTraitsMech	Domain of unknown function (DUF1868)	O55739 Uncharacterized protein 127L	canonical example family classification
2H-phosphodiest (PF08975)	ProteinTraitsMech	Domain of unknown function (DUF1868)		trait identifier

Curation history and reviews

No retained curation events supplied.

No retained review supplied.

Record source

data/families/PF08975.yaml
Family YAML in this build

Download this family (JSON)

Status and evidence

Seed status: A name-based classification of frozen InterPro/Pfam metadata. UNKNOWN CANDIDATE means the metadata explicitly says the function is unknown. KNOWN HISTORICAL DUF means a DUF name matched without that wording; this heuristic is not proof of a known function and does not establish experimental characterization. EX DUF means Pfam renamed the family away from a DUF/UPF name, as recorded in Pfam's previous identifiers; a rename usually follows published work on some members but is naming history, not proof of function for every member. Some EX DUF families' current names or descriptions still say the function is unknown; their classification basis lists this, and scoring does not treat them as characterized. FALSE POSITIVE TEXT HIT means the naming rules did not match.
Characterization: A separate evidence-scoring result. UNSCORED means no score has been calculated; it is not evidence that the family lacks a known function. Missing scores are not negative evidence. PARTIALLY CHARACTERIZED has partial support; KNOWN HISTORICAL DUF can inherit the seed label or reflect a known-function signal. Neither label implies experimental validation.
Evidence counts: Source-specific signals, not unique proteins, publications, or confidence scores. Known counts Rhea reactions and experimentally supported GO molecular-function annotations. Partial counts functional/domain assignments. Context counts structural, environmental, orthology, interaction and neighborhood signals; context alone does not assign function. Repeated annotations may not be independent.
Curation status: Reported separately from seed classification and characterization. SNAPSHOT ONLY means no curated metadata was supplied for this build. SEEDED denotes a source-derived record, not an expert-reviewed functional claim.
Missing counts: Not available means the source did not supply that counter. A zero is a reported count. Not scored means evidence counts are unavailable.