Gpdh3-PB is a native 1291-residue Drosophila glycerol-3-phosphate-dehydrogenase-related isoform. It contains the paired NAD-dependent GPDH domains near its N terminus followed by a long extension, supporting retained glycerol-3-phosphate/dihydroxyacetone-phosphate interconversion chemistry. The physiological flux direction, oligomeric state and function of the extension remain unresolved.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005975 carbohydrate metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: Glycerol-3-phosphate metabolism specifies the broad carbohydrate process. Reason: The domain architecture supports GPDH chemistry; the specific substrate process is more informative than the generic carbohydrate metabolism parent. Proposed replacements: glycerol-3-phosphate metabolic process Supporting Evidence: file:DROME/Gpdh3/Gpdh3-uniprot.txt DR InterPro; IPR017751; G3P_DH_NAD-dep_euk. |
| GO:0006072 glycerol-3-phosphate metabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: Glycerol-3-phosphate metabolism follows the conserved GPDH reaction. Reason: The native long isoform retains both GPDH domains, supporting interconversion of glycerol-3-phosphate and dihydroxyacetone phosphate. Net physiological flux in the tissues expressing this isoform has not been measured. Supporting Evidence: file:genes/DROME/Gpdh3/Gpdh3-flybase.txt Gpdh3-PB FBpp0297799 144.8 1291 4.81 E1JIT1 NP_001163685 ACZ94981 file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 6..173 file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 194..312 |
| GO:0006650 glycerophospholipid metabolic process | IEA GO_REF:0000041 | UNDECIDED | Summary: A dedicated glycerophospholipid-metabolism role needs pathway-level evidence. Reason: Glycerol-3-phosphate can feed lipid synthesis, but the enzyme module alone does not establish that the selected long isoform contributes materially to glycerophospholipid metabolism rather than redox shuttling or another metabolic context. Supporting Evidence: file:DROME/Gpdh3/Gpdh3-uniprot.txt DR InterPro; IPR017751; G3P_DH_NAD-dep_euk. |
| GO:0016616 oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor | IEA GO_REF:0000002 | MODIFY | Summary: Glycerol-3-phosphate dehydrogenase specifies the broad oxidoreductase class. Reason: The paired GPDH domains and eukaryotic GPDH signature identify the substrate-associated enzyme architecture more specifically than generic NAD(P)-dependent alcohol oxidation. Proposed replacements: glycerol-3-phosphate dehydrogenase (NAD+) activity Supporting Evidence: file:DROME/Gpdh3/Gpdh3-uniprot.txt DR InterPro; IPR017751; G3P_DH_NAD-dep_euk. |
| GO:0042803 protein homodimerization activity | IEA GO_REF:0000002 | UNDECIDED | Summary: Homodimerization of the long Gpdh3 product has not been demonstrated. Reason: Conventional GPDH oligomerization cannot be transferred uncritically to a protein with a large native extension. The complete catalytic module is present, but the assembly state of Gpdh3-PB remains unmeasured. Supporting Evidence: file:genes/DROME/Gpdh3/Gpdh3-flybase.txt Gpdh3-PB FBpp0297799 144.8 1291 4.81 E1JIT1 NP_001163685 ACZ94981 file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 6..173 file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 194..312 |
| GO:0046168 glycerol-3-phosphate catabolic process | IEA GO_REF:0000120 | UNDECIDED | Summary: Net glycerol-3-phosphate catabolism is not established for Gpdh3-PB. Reason: The reversible oxidoreductase architecture supports chemical interconversion, but a reaction written in the oxidative direction does not establish in-vivo catabolic flux. Tissue-specific metabolite or flux evidence is missing. Supporting Evidence: file:genes/DROME/Gpdh3/Gpdh3-flybase.txt Gpdh3-PB FBpp0297799 144.8 1291 4.81 E1JIT1 NP_001163685 ACZ94981 file:DROME/Gpdh3/Gpdh3-uniprot.txt DR InterPro; IPR017751; G3P_DH_NAD-dep_euk. |
| GO:0051287 NAD binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: NAD binding is a cofactor feature of the GPDH module. Reason: The target retains the NAD-dependent GPDH N-terminal domain. This supports cofactor binding as part of the reaction, not a separate primary activity. Supporting Evidence: file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 6..173 file:DROME/Gpdh3/Gpdh3-uniprot.txt DR InterPro; IPR017751; G3P_DH_NAD-dep_euk. |
| GO:0141152 glycerol-3-phosphate dehydrogenase (NAD+) activity | IEA GO_REF:0000120 | ACCEPT | Summary: The complete NAD-dependent glycerol-3-phosphate dehydrogenase module is retained. Reason: FlyBase explicitly identifies E1JIT1 as the native 1291-residue Gpdh3-PB isoform. Its N-terminal cofactor-binding and C-terminal GPDH catalytic domains are both present within residues 6-312, supporting the conserved reaction despite the long extension. The domain evidence supports an evolutionary enzyme inference; it is not a direct assay of the long isoform. Supporting Evidence: file:genes/DROME/Gpdh3/Gpdh3-flybase.txt Gpdh3-PB FBpp0297799 144.8 1291 4.81 E1JIT1 NP_001163685 ACZ94981 file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 6..173 file:DROME/Gpdh3/Gpdh3-uniprot.txt FT DOMAIN 194..312 file:DROME/Gpdh3/Gpdh3-uniprot.txt DR InterPro; IPR017751; G3P_DH_NAD-dep_euk. |
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