ttv

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005789 endoplasmic reticulum membrane	IEA GO_REF:0000044	UNDECIDED	Summary: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv. Reason: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv. It might associate with membranes through other proteins, but this has not been demonstrated. The full-length membrane annotation does not independently establish ER-membrane residence for PC; the correct compartment remains unresolved. Supporting Evidence: file:DROME/ttv/ttv-bioinformatics/RESULTS.md The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained. file:DROME/ttv/ttv-flybase.txt ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504
GO:0009101 glycoprotein biosynthetic process	IEA GO_REF:0000002	UNDECIDED	Summary: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Reason: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Catalytic potential remains plausible, but no exact-isoform assay establishes native activity, trafficking or participation in glycan synthesis. Keep this annotation undecided rather than transfer all full-length Ttv properties. Supporting Evidence: file:DROME/ttv/ttv-bioinformatics/RESULTS.md The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained. file:DROME/ttv/ttv-flybase.txt ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504
GO:0016020 membrane	IEA GO_REF:0000002	UNDECIDED	Summary: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv. Reason: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv. It might associate with membranes through other proteins, but this has not been demonstrated. The full-length membrane annotation does not independently establish ER-membrane residence for PC; the correct compartment remains unresolved. Supporting Evidence: file:DROME/ttv/ttv-bioinformatics/RESULTS.md The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained. file:DROME/ttv/ttv-flybase.txt ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504
GO:0016757 glycosyltransferase activity	IEA GO_REF:0000002	UNDECIDED	Summary: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Reason: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Catalytic potential remains plausible, but no exact-isoform assay establishes native activity, trafficking or participation in glycan synthesis. Keep this annotation undecided rather than transfer all full-length Ttv properties. Supporting Evidence: file:DROME/ttv/ttv-bioinformatics/RESULTS.md The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained. file:DROME/ttv/ttv-flybase.txt ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504 PMID:36593275 EXT1 and EXT2, where each protein monomer contains distinct GT47 (GT-B fold) and GT64 (GT-A fold) glycosyltransferase domains.
GO:1901135 carbohydrate derivative metabolic process	IEA GO_REF:0000117	UNDECIDED	Summary: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Reason: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Catalytic potential remains plausible, but no exact-isoform assay establishes native activity, trafficking or participation in glycan synthesis. Keep this annotation undecided rather than transfer all full-length Ttv properties. Supporting Evidence: file:DROME/ttv/ttv-bioinformatics/RESULTS.md The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained. file:DROME/ttv/ttv-flybase.txt ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504

GO Term

Evidence

Action

Reason

GO:0005789 endoplasmic reticulum membrane

IEA
GO_REF:0000044

UNDECIDED

Summary: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv.

Reason: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv. It might associate with membranes through other proteins, but this has not been demonstrated. The full-length membrane annotation does not independently establish ER-membrane residence for PC; the correct compartment remains unresolved.

Supporting Evidence:

file:DROME/ttv/ttv-bioinformatics/RESULTS.md

The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained.

file:DROME/ttv/ttv-flybase.txt

ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504

GO:0009101 glycoprotein biosynthetic process

IEA
GO_REF:0000002

UNDECIDED

Summary: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting.

Reason: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting. Catalytic potential remains plausible, but no exact-isoform assay establishes native activity, trafficking or participation in glycan synthesis. Keep this annotation undecided rather than transfer all full-length Ttv properties.

Supporting Evidence:

file:DROME/ttv/ttv-bioinformatics/RESULTS.md

The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained.

file:DROME/ttv/ttv-flybase.txt

ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504

GO:0016020 membrane

IEA
GO_REF:0000002

UNDECIDED

Summary: The source protein is a C-terminal isoform lacking the N-terminal membrane anchor of full-length Ttv.

Supporting Evidence:

file:DROME/ttv/ttv-bioinformatics/RESULTS.md

The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained.

file:DROME/ttv/ttv-flybase.txt

ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504

GO:0016757 glycosyltransferase activity

IEA
GO_REF:0000002

UNDECIDED

Summary: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting.

Supporting Evidence:

file:DROME/ttv/ttv-bioinformatics/RESULTS.md

The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained.

file:DROME/ttv/ttv-flybase.txt

ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504

PMID:36593275

EXT1 and EXT2, where each protein monomer contains distinct GT47 (GT-B fold) and GT64 (GT-A fold) glycosyltransferase domains.

GO:1901135 carbohydrate derivative metabolic process

IEA
GO_REF:0000117

UNDECIDED

Summary: The native short PC product retains a C-terminal glycosyltransferase region but lacks the N-terminal region needed for the full-length domain architecture and membrane targeting.

Supporting Evidence:

file:DROME/ttv/ttv-bioinformatics/RESULTS.md

The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained.

file:DROME/ttv/ttv-flybase.txt

ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504

External Prediction Reviews

These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.

ProtNLM2 External predictions

View prediction review YAML · ttv-protnlm-predictions-review.yaml · Review status: COMPLETE

The native short Ttv isoform retains a conserved C-terminal GT64 glycosyltransferase domain, but its autonomous activity and physiological access to substrates are unverified.

Source documents: genes/DROME/ttv/ttv-protnlm-source.json · genes/DROME/ttv/ttv-bioinformatics/RESULTS.md · genes/DROME/ttv/ttv-flybase.txt · genes/DROME/ttv/ttv-hypotheses/fly41-short-isoform-glycosyltransferase/openscientist.md

Review score: 2 = concordant with evidence; 1 = uncertain; 0 = discordant with evidence. This is an assessment score, not a model probability.

GO:0016757 glycosyltransferase activity GO_MF

UNC — Uncertain Review score: 1/2

Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08 · file:DROME/ttv/ttv-protnlm-source.json

Review rationale: D5SHU8 is the 299-residue ttv-PC isoform, not the full-length 760-residue protein. The retained C-terminal region contains the annotated catalytic Asp and multiple ligand-binding residues, so short length does not justify categorical refutation of glycosyltransferase activity. However, the other domain and N-terminal targeting/anchor region are absent, and the current data do not establish folding, complex support or substrate access in PC. An equivalent electronic annotation exists but adds no independent validation. OpenScientist found the broad parent term defensible by homology but still cautioned that catalytic evidence is from full-length Ttv, not isolated D5SHU8. Target-specific activity or a convincing domain-level functional analysis is missing; UNC preserves this distinction.

Supporting Evidence:

file:DROME/ttv/ttv-bioinformatics/RESULTS.md: "The C-terminal glycosyltransferase-region active-site Asp670 maps to target Asp209, and the source-record nucleotide-sugar/metal-binding residues in this region are retained."
file:DROME/ttv/ttv-flybase.txt: "ttv-PC FBpp0305368 34.4 299 9.71 D5SHU8 NP_001260972 AGB93504"
PMID:36593275: "EXT1 and EXT2, where each protein monomer contains distinct GT47 (GT-B fold) and GT64 (GT-A fold) glycosyltransferase domains."
file:DROME/ttv/ttv-hypotheses/fly41-short-isoform-glycosyltransferase/openscientist.md: "Of the nine canonical catalytic/substrate-binding residues, **8 are retained** in D5SHU8, including the active-site **Asp670 → Asp209** and the **DED binding motif (canonical 581–583 → D5SHU8 120–122)**"

Deep Research

Falcon

(ttv-deep-research-falcon.md)

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OpenScientist

(ttv-hypotheses/fly41-short-isoform-glycosyltransferase/openscientist.md)

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📚 Additional Documentation

Bioinformatics Results

(RESULTS.md)

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Gene Description

Existing Annotations Review

References

External Prediction Reviews

ProtNLM2 External predictions

Deep Research

Falcon

OpenScientist

📚 Additional Documentation

Notes

Bioinformatics Results

📄 View Raw YAML