Focused fly function hypothesis

Hypothesis: The Drosophila melanogaster protein D5SHU8 has glycosyltransferase activity.

Target: Drosophila melanogaster (NCBITaxon:7227), UniProt D5SHU8. Gene label: ttv. Verify identity and isoform independently; the gene label is not evidence for the hypothesis.

Original prediction

F:glycosyltransferase activity

Decisive question

Assess glycosyltransferase activity of the supplied exact sequence. Resolve its annotated transcript/isoform and compare it with structurally and biochemically characterized EXT-family proteins and relevant Drosophila partners. Determine which catalytic domain and substrate-binding architecture are present, whether the protein can fold into a functional catalytic unit, and whether partner interactions or targeting are required for intrinsic catalysis versus an in-vivo glycan-biosynthesis role. Neither short length nor a conserved catalytic residue alone settles the question. Distinguish experimentally demonstrated isolated-domain activity from structural plausibility.

Identity and sequence

• Target record: https://www.uniprot.org/uniprotkb/D5SHU8/entry
• FlyBase identifier(s) from the cohort identity mapping: FBgn0265974.
• Frozen current UniProt sequence: 299 residues; SHA-256 76d919802eaf321c50ecd217e0e45d5f74f2ec9e6fb7a3806aa74f3433760493.
• The sequence was frozen for the fly cohort on 2026-09-08. It is not established as the original prediction-time input. Analyze this sequence explicitly and document any alternate accession, version or isoform you analyze.

>D5SHU8 Drosophila melanogaster ttv
MPFLLNSMGAEPRHNYTAVIYVQIGAALGPNAALYKLVRTITKSQFVERILVLWAADRPL
PLKKRWPPTSHIPLHVISLGGSTRSQGAGPTSQTTEGRPSISQRFLPYDEIQTDAVLSLD
EDAILNTDELDFAYTVWRDFPERIVGYPARAHFWDDSKNAWGYTSKWTNYYSIVLTGAAF
YHRYYNYLYTNWLSLLLLKTVQQSSNCEDILMNLLVSHVTRKPPIKVTQRKGYKDRETGR
SPWNDPDHFIQRQSCLNTFAAVFGYMPLIRSNLRMDPMLYRDPVSNLRKKYRQIELVGS

Primary literature lead to inspect (not a preassigned conclusion): https://pubmed.ncbi.nlm.nih.gov/36593275/

Evidence and deliverable

Use primary literature and public sequence, structural and genomic resources. This is a focused mechanistic investigation, not a general gene overview. Seek supporting, contrary and competing explanations; an unresolved result is acceptable. Distinguish direct fly experiments, justified transfers and results on a different isoform. Do not equate missing target experiments with evidence of absence.

Do not consult the ai-gene-review repository's current reviews, generated research summaries or local bioinformatics analyses; these are held out for comparison. Agreement with ARBA or repeated prediction text does not validate the biology. Save executed methods/code, actual analysis outputs, sequence identifiers and primary-source URLs/DOIs/PMIDs. Report decisive evidence and limitations, not just a verdict. Do not fabricate computations or use docking/structural resemblance alone as experimental validation.