CG33116

UniProt ID: Q9VIU4
Organism: Drosophila melanogaster
Review Status: DRAFT
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Gene Description

CG33116 is an endoplasmic-reticulum membrane member of the choline/ethanolamine phosphotransferase family. It is inferred to catalyze the final Kennedy-pathway transfer of phosphoethanolamine from CDP-ethanolamine to diacylglycerol, producing phosphatidylethanolamine. Its ER localization distinguishes it from Golgi-associated relatives involved in phospholipid and sphingolipid metabolism.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0004307 ethanolaminephosphotransferase activity
IBA
GO_REF:0000033 		ACCEPT
Summary: CG33116/dCCS1 belongs to the choline/ethanolamine phosphotransferase subfamily and is an ER protein.
Reason: CG33116/dCCS1 belongs to the choline/ethanolamine phosphotransferase subfamily and is an ER protein. The primary comparative study separates this protein from ceramide phosphoethanolamine synthase CG4585, and the PAINT ancestral assignment supports conserved phosphatidylethanolamine synthesis from CDP-ethanolamine and diacylglycerol. Substrate specificity is a phylogenetic inference; the localization experiment is direct.
Supporting Evidence:
PMID:23449981
three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
GO:0005783 endoplasmic reticulum
IDA
PMID:23449981
Ceramide phosphoethanolamine biosynthesis in Drosophila is m... 		ACCEPT
Summary: Tagged CG33116/dCCS1 localizes to the ER in Drosophila S2 cells and in the parallel HeLa-cell assay.
Reason: Tagged CG33116/dCCS1 localizes to the ER in Drosophila S2 cells and in the parallel HeLa-cell assay. Its membrane phosphotransferase architecture makes ER membrane residence consistent with the directly observed compartment.
Supporting Evidence:
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
file:DROME/CG33116/CG33116-uniprot.txt
DR InterPro; IPR000462; CDP-OH_P_trans.
GO:0005789 endoplasmic reticulum membrane
IBA
GO_REF:0000033 		ACCEPT
Summary: Tagged CG33116/dCCS1 localizes to the ER in Drosophila S2 cells and in the parallel HeLa-cell assay.
Reason: Tagged CG33116/dCCS1 localizes to the ER in Drosophila S2 cells and in the parallel HeLa-cell assay. Its membrane phosphotransferase architecture makes ER membrane residence consistent with the directly observed compartment.
Supporting Evidence:
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
file:DROME/CG33116/CG33116-uniprot.txt
DR InterPro; IPR000462; CDP-OH_P_trans.
GO:0005794 Golgi apparatus
IBA
GO_REF:0000033 		REMOVE
Summary: The inherited Golgi placement does not fit the target-specific localization comparison.
Reason: The inherited Golgi placement does not fit the target-specific localization comparison. CG33116/dCCS1 localized exclusively to the ER, whereas the related dCCS3 and dCCS4 proteins associated with Golgi markers. This experimentally resolved localization divergence argues against propagating Golgi residence to CG33116 from the shared ancestral node.
Supporting Evidence:
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
GO:0006646 phosphatidylethanolamine biosynthetic process
IBA
GO_REF:0000033 		ACCEPT
Summary: CG33116/dCCS1 belongs to the choline/ethanolamine phosphotransferase subfamily and is an ER protein.
Reason: CG33116/dCCS1 belongs to the choline/ethanolamine phosphotransferase subfamily and is an ER protein. The primary comparative study separates this protein from ceramide phosphoethanolamine synthase CG4585, and the PAINT ancestral assignment supports conserved phosphatidylethanolamine synthesis from CDP-ethanolamine and diacylglycerol. Substrate specificity is a phylogenetic inference; the localization experiment is direct.
Supporting Evidence:
PMID:23449981
three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
GO:0008654 phospholipid biosynthetic process
IEA
GO_REF:0000002 		MODIFY
Summary: The broad annotation is consistent with the identified ER choline/ethanolamine phosphotransferase.
Reason: The broad annotation is consistent with the identified ER choline/ethanolamine phosphotransferase. The specific ER compartment or phosphatidylethanolamine-synthesis reaction conveys its biological role more precisely; this combines direct localization with the supported subfamily inference.
Supporting Evidence:
PMID:23449981
three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
GO:0016020 membrane
IEA
GO_REF:0000120 		MODIFY
Summary: The broad annotation is consistent with the identified ER choline/ethanolamine phosphotransferase.
Reason: The broad annotation is consistent with the identified ER choline/ethanolamine phosphotransferase. The specific ER compartment or phosphatidylethanolamine-synthesis reaction conveys its biological role more precisely; this combines direct localization with the supported subfamily inference.
Proposed replacements: endoplasmic reticulum membrane
Supporting Evidence:
PMID:23449981
three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase
GO:0016780 phosphotransferase activity, for other substituted phosphate groups
IEA
GO_REF:0000002 		MODIFY
Summary: The broad annotation is consistent with the identified ER choline/ethanolamine phosphotransferase.
Reason: The broad annotation is consistent with the identified ER choline/ethanolamine phosphotransferase. The specific ER compartment or phosphatidylethanolamine-synthesis reaction conveys its biological role more precisely; this combines direct localization with the supported subfamily inference.
Supporting Evidence:
PMID:23449981
three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)
PMID:23449981
Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase

Core Functions

Synthesizes phosphatidylethanolamine in the ER by a conserved choline/ethanolamine phosphotransferase reaction.

Molecular Function:
ethanolaminephosphotransferase activity
Directly Involved In:
phosphatidylethanolamine biosynthetic process
Cellular Locations:
endoplasmic reticulum membrane
Supporting Evidence:
  • PMID:23449981
    three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)
  • PMID:23449981
    Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase

References

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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 · CG33116-protnlm-predictions-review.yaml · Review status: COMPLETE

All three broad predictions are supported but less precise than the ER-localized phosphatidylethanolamine-synthesis function.

Source documents: projects/PROTNLM_EVALUATION/fly-benchmark/predictions.jsonl.gz · genes/DROME/CG33116/CG33116-predictions-source.json

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

GO:0016780 phosphotransferase activity, for other substituted phosphate groups GO_MF
LSP — Less precise than existing annotation Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: The phosphotransferase prediction agrees with CG33116 membership in the choline/ethanolamine phosphotransferase subfamily established in a primary comparative study. The PAINT assignment of ethanolaminephosphotransferase activity is more specific and is a reasonable conserved-reaction inference for this ER protein. The exact substrate activity has not been directly measured in the cited localization study.
Supporting Evidence:
  • PMID:23449981: "three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)"
  • PMID:23449981: "Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase"
GO:0016020 membrane GO_CC
LSP — Less precise than existing annotation Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: Membrane residence is supported by the membrane phosphotransferase architecture and direct localization of CG33116/dCCS1 to the ER. The existing ER-membrane annotation specifies the relevant compartment and is more informative than membrane.
Supporting Evidence:
  • PMID:23449981: "Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase"
  • file:DROME/CG33116/CG33116-uniprot.txt: "DR InterPro; IPR000462; CDP-OH_P_trans."
GO:0008654 phospholipid biosynthetic process GO_BP
LSP — Less precise than existing annotation Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: The predicted phospholipid biosynthetic process is consistent with the conserved choline/ethanolamine phosphotransferase subfamily and ER localization. The curated phosphatidylethanolamine biosynthetic process is the supported, more specific pathway assignment. This inference concerns glycerophospholipid synthesis, distinct from the ceramide phosphoethanolamine synthesis experimentally assigned to CG4585.
Supporting Evidence:
  • PMID:23449981: "three proteins from the CEPT subfamily (dCCS1/CG33116, dCCS2/CG6016 and dCCS3/CG7149)"
  • PMID:23449981: "Both dCCS1-V5 and dCCS2-V5 localized exclusively to the ER, as evidenced by a reticular and nuclear envelope staining that overlapped extensively with the ER marker PE-methyltransferase"

Deep Research

Falcon

(CG33116-deep-research-falcon.md)

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📚 Additional Documentation

Notes

(CG33116-notes.md)

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