PF03661: TMEM33_Pom33

Transmembrane protein 33/Nucleoporin POM33

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

Grounding

PF03661: Transmembrane protein 33/Nucleoporin POM33
IPR005344: integrated entry for Transmembrane protein 33/Nucleoporin POM33

Source description

This is an integral membrane protein family. Family members include TMEM33/Pom33 proteins. Budding yeast Pom33 is a transmembrane nucleoporin that contributes to proper distribution and/or efficient assembly of nuclear pores [InterPro reference PUB00075311]. Proteins in this entry also include Tts1 from fission yeasts [InterPro reference PUB00075313], Kr-h2 (krueppel homologue 2) from flies [InterPro reference PUB00075314] and TMEM33 from vertebrates [InterPro reference PUB00085045]. Tts1 is required for the correct positioning of the cellular division plane by delimiting the actomyosin ring assembly at the cell equator [InterPro reference PUB00075313]. Kr-h2 is a member of the dosage-dependent hierarchy effective upon white gene expression [InterPro reference PUB00075314]. TMEM33 regulates the tubular structure of endoplasmic reticulum by suppressing the membrane-shaping activity of reticulons [InterPro reference PUB00085045].

Evidence and references

InterPro entry and its literature references. PUB identifiers are internal InterPro references, not PubMed identifiers. Unresolved citations link to the originating entry.
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

6 verified sequence examples. FASTA

UniProt	Protein / organism	Sequence	Provenance
P57088	Transmembrane protein 33 Homo sapiens	247 aa; version 2 UniProt 2026_03	PTM REGISTRY MIRROR 4 sibling references ProteinTraitsMech: GO:1903899 ProteinTraitsMech: GO:1903371 ProteinTraitsMech: Pfam:PF03661 ProteinTraitsMech: UniProtKB:P57088
Q12144	Pore and endoplasmic reticulum protein of 33 kDa Saccharomyces cerevisiae (strain ATCC 204508 / S288c)	273 aa; version 1 UniProt 2026_03	UNIPROT FETCH 1 sibling references ProteinTraitsMech: Pfam:PF03661
Q12164	Pore membrane protein of 33 kDa Saccharomyces cerevisiae (strain ATCC 204508 / S288c)	279 aa; version 1 UniProt 2026_03	UNIPROT FETCH 1 sibling references ProteinTraitsMech: Pfam:PF03661
Q9CR67	Transmembrane protein 33 Mus musculus	247 aa; version 1 UniProt 2026_03	UNIPROT FETCH 3 sibling references ProteinTraitsMech: GO:1903899 ProteinTraitsMech: GO:1903371 ProteinTraitsMech: Pfam:PF03661
Q9V447	Krueppel homolog 2 Drosophila melanogaster	276 aa; version 1 UniProt 2026_03	UNIPROT FETCH 1 sibling references ProteinTraitsMech: Pfam:PF03661
Q9XWV0	Transmembrane protein 33 homolog Caenorhabditis elegans	271 aa; version 1 UniProt 2026_03	UNIPROT FETCH 1 sibling references ProteinTraitsMech: Pfam:PF03661

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: 4,537
matches: 4,581
proteomes: 3,263
taxa: 8,676
structures: 0
alphafold models: 3,883
domain architectures: 71

Classification basis

pfam previous unknown name

No scoring reasons supplied.

Related Mech records

This family joined the worklist after the frozen cross-Mech scan, so other Mechs were not searched for it. Missing links here are not evidence that other Mechs lack it; rows shown come from mentions of a former DUF/UPF name.

No cross-Mech examples are present in the supplied snapshot.

Curation history and reviews

No retained curation events supplied.

No retained review supplied.

Record source

data/families/PF03661.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.