DpuGr29 is a Daphnia pulex gustatory-receptor-family membrane protein, encoded by DAPPUDRAFT_346859. Its multipass membrane architecture and placement in a Daphnia-expanded chemoreceptor clade support a role in chemical sensing and chemosensory behavior. Its ligand, sensory modality and detailed tissue distribution remain unresolved. Experimentally characterized insect gustatory receptors form ligand-gated cation channels, providing a mechanistic hypothesis for DpuGr29 whose ionic selectivity and subunit requirements have not been established.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008049 male courtship behavior | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Retain the inherited male-courtship capacity as an inferred, non-core behavioral role. Reason: The actual PTHR21143 tree places exact E9FXF3/DAPPUDRAFT_346859 below the positive arthropod PTN001080220 courtship IBD, with no on-lineage negative assertion. PMID:19383158 establishes a Daphnia-specific expansion rather than one-to-one dipteran orthology, but does not demonstrate loss of the deeper ancestral capacity. The focused report did not inspect the tree and rejects the term primarily from absent target experiments and insect-only donors; those arguments do not overturn IBA. Retain the positive inferred role as behavioral context while leaving the target ligand, tissue, circuit and direction of courtship modulation unestablished. Neither cyclical parthenogenesis nor the BP/MF distinction excludes this role. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN001080220 SUPPORTS TRANSFER Actual target leaf PTN002326688 descends from the positive arthropod node. The known Daphnia receptor expansion does not itself establish ancestral functional loss; accepted as inferred behavioral capacity without specifying a ligand or circuit. Supporting Evidence: PMID:19383158 The first consists of 37 proteins in the middle of Figure 1 in two well-supported clusters, specifically Grs1–29, and 47–54. file:DAPPU/DpuGr29/DpuGr29-report-assessment.md The live PTHR21143 POST tree places exact E9FXF3/DAPPUDRAFT_346859 at PTN002326688 below PTN001080220 PMID:19765987 This phenotype was rescued by the Gr33a+ transgene |
| GO:0007635 chemosensory behavior | IBA GO_REF:0000033 | ACCEPT | Summary: This annotation is based on phylogenetic inference from Drosophila GR genes that function in chemosensory behavior. Given that GRs are chemoreceptors that detect chemical stimuli and trigger behavioral responses, this annotation is appropriate for DpuGr29. Daphnia relies heavily on chemosensory detection for predator avoidance, food finding, and environmental sensing. Reason: Chemosensory behavior (GO:0007635) is defined as "behavior that is dependent upon the sensation of chemicals." GRs are established chemoreceptors across arthropods. Daphnia pulex has an expanded GR repertoire (58 genes) and relies heavily on chemosensory detection for predator avoidance (kairomone detection), food finding, and environmental sensing. The phylogenetic inference from Drosophila GRs to Daphnia GRs for this general chemosensory function is well-supported, as the fundamental role of GRs as chemoreceptors mediating behavioral responses is conserved across arthropods. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001080220 SUPPORTS TRANSFER Exact target lineage is below this positive IBD. Retained as a conserved inference; direct Daphnia expression or behavioral assays are not claimed. Supporting Evidence: PMID:19383158 This repertoire of 58 chemoreceptors presumably mediates the many chemoperception abilities of waterfleas. file:DAPPU/DpuGr29/DpuGr29-report-assessment.md the positive arthropod courtship and chemosensory-behavior IBD node. |
| GO:0030424 axon | IBA GO_REF:0000033 | ACCEPT | Summary: Retain the ancestral neuronal axon localization inference. Reason: PAINT places this localization at PTN000475107 on the chemoreceptor family tree. A divergent ligand repertoire does not itself demonstrate loss of neuronal membrane distribution. The previous rationale required target-specific expression and discounted soma localization for low informativeness; neither challenges the ancestral location inference. The exact tissue distribution remains unmeasured, so this is explicitly accepted as IBA rather than as direct Daphnia microscopy. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000475107 SUPPORTS TRANSFER Exact target lineage is below this positive IBD. Retained as a conserved inference; direct Daphnia expression or behavioral assays are not claimed. Supporting Evidence: file:DAPPU/DpuGr29/DpuGr29-deep-research-falcon.md GRs in Daphnia are expected to localize to membranes of chemosensory neurons file:DAPPU/DpuGr29/DpuGr29-report-assessment.md Root PTN000475107 supplies the three neuronal locations. |
| GO:0030425 dendrite | IBA GO_REF:0000033 | ACCEPT | Summary: Retain the ancestral neuronal dendrite localization inference. Reason: PAINT places this localization at PTN000475107 on the chemoreceptor family tree. A divergent ligand repertoire does not itself demonstrate loss of neuronal membrane distribution. The previous rationale required target-specific expression and discounted soma localization for low informativeness; neither challenges the ancestral location inference. The exact tissue distribution remains unmeasured, so this is explicitly accepted as IBA rather than as direct Daphnia microscopy. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000475107 SUPPORTS TRANSFER Exact target lineage is below this positive IBD. Retained as a conserved inference; direct Daphnia expression or behavioral assays are not claimed. Supporting Evidence: file:DAPPU/DpuGr29/DpuGr29-deep-research-falcon.md GRs in Daphnia are expected to localize to membranes of chemosensory neurons file:DAPPU/DpuGr29/DpuGr29-report-assessment.md Root PTN000475107 supplies the three neuronal locations. |
| GO:0043025 neuronal cell body | IBA GO_REF:0000033 | ACCEPT | Summary: Retain the ancestral neuronal cell-body localization inference. Reason: PAINT places this localization at PTN000475107 on the chemoreceptor family tree. A divergent ligand repertoire does not itself demonstrate loss of neuronal membrane distribution. The previous rationale required target-specific expression and discounted soma localization for low informativeness; neither challenges the ancestral location inference. The exact tissue distribution remains unmeasured, so this is explicitly accepted as IBA rather than as direct Daphnia microscopy. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000475107 SUPPORTS TRANSFER Exact target lineage is below this positive IBD. Retained as a conserved inference; direct Daphnia expression or behavioral assays are not claimed. Supporting Evidence: file:DAPPU/DpuGr29/DpuGr29-deep-research-falcon.md GRs in Daphnia are expected to localize to membranes of chemosensory neurons file:DAPPU/DpuGr29/DpuGr29-report-assessment.md Root PTN000475107 supplies the three neuronal locations. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: This annotation is based on UniProt subcellular location prediction indicating DpuGr29 is a multi-pass membrane protein localized to the cell membrane. This is consistent with the 7TM architecture of gustatory receptors. Reason: The target is a multipass membrane chemoreceptor with eight Phobius-predicted segments in its current sequence record and a 7TM-chemoreceptor domain assignment. Exact helix counting can differ among prediction models; it does not weaken the family-supported cell-surface localization. This is a conserved inference, not direct target imaging. Supporting Evidence: file:DAPPU/DpuGr29/DpuGr29-deep-research-falcon.md Daphnia GRs are members of the arthropod GR/OR chemoreceptor superfamily with characteristic 7 transmembrane helices and a conserved motif in TM7 (TYhhhhhQF) |
| GO:0016020 membrane | IEA GO_REF:0000002 | ACCEPT | Summary: This annotation is based on InterPro domain IPR013604 (7TM_chemorcpt) indicating membrane localization. This is correct but less specific than GO:0005886 (plasma membrane) which is also annotated. Reason: The annotation is accurate - DpuGr29 contains the 7TM chemoreceptor domain (IPR013604) which is a multi-pass transmembrane domain. While GO:0016020 (membrane) is a more general term than GO:0005886 (plasma membrane), both annotations are appropriate. The IEA annotation based on InterPro domain mapping is well-supported by structural predictions showing 7-8 transmembrane helices. Supporting Evidence: file:DAPPU/DpuGr29/DpuGr29-deep-research-falcon.md D. pulex GR genes typically share a characteristic intron-exon structure with phase-0 introns; this 7TM chemoreceptor architecture aligns with the InterPro 7TM_chemorcpt and Pfam 7tm_7 domain assignments noted for E9FXF3 (PF08395; IPR013604) |
| GO:0050909 sensory perception of taste | IEA GO_REF:0000002 | UNDECIDED | Summary: Aquatic gustation is possible, but the sensory modality of the DpuGr29 clade is unresolved. Reason: GO:0050909 concerns direct chemical detection, usually by contact with chemoreceptor cells; it does not imply terrestrial life. The primary Daphnia paper explicitly discusses both contact taste and detection of dissolved chemicals. DpuGr29 belongs to a lineage-expanded clade without an established ligand or expression site, so the InterPro family mapping cannot presently resolve taste versus another chemical sense. Generalizing solely because Daphnia is aquatic was unjustified. The focused report recommends a generic taste inference but supplies no new evidence resolving contact versus another chemosensory modality, and the inspected PAINT ancestry does not carry a taste assertion. This remains an unresolved family-to-modality mapping, not a demonstrated loss. Supporting Evidence: PMID:19383158 which they do using both a classic "taste" mode involving physical contact with objects, as well as what might be considered a "smell" mode in which they sense dissolved chemicals in the water. file:DAPPU/DpuGr29/DpuGr29-report-assessment.md The report CSV recommends retaining taste as generic, but does not resolve the contact-versus-non-contact sensory modality. PMID:19765987 it includes members that function in both contact [1-3, 6-11] and non-contact chemosensation |
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Download this section (compressed HTML)Q: What is the ligand specificity of DpuGr29 (sugars, bitter compounds, pheromones)?
Q: In which tissues/cells is DpuGr29 expressed in Daphnia?
Q: Does DpuGr29 function as a homomer or heteromer with other Daphnia GRs?
Q: Which ligand, sensory modality and subunit composition does DpuGr29 use? Actual ancestry supports a conserved courtship capacity, but its Daphnia circuit and behavioral direction remain unknown. The retained TYLVILYQF motif and BmGr9 structure support a channel hypothesis without establishing target conductance/selectivity; the prior GO:0099094 NEW remains withdrawn.
Experiment: Heterologous expression of DpuGr29 in Xenopus oocytes or HEK293 cells followed by calcium imaging or electrophysiology to identify ligand specificity
Hypothesis: DpuGr29 responds to specific chemical ligands (sugars, bitter compounds, or environmental cues)
Type: functional assay
Experiment: In situ hybridization or single-cell RNA-seq of Daphnia chemosensory organs to determine DpuGr29 expression pattern
Hypothesis: DpuGr29 is expressed in chemosensory neurons of antennules or feeding appendages
Type: expression analysis
Experiment: AlphaFold2 structure prediction and molecular docking to identify potential ligand-binding residues
Hypothesis: Structural modeling can identify candidate ligands based on binding pocket architecture
Type: computational analysis
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