BBS-7 (also known as OSM-12) is a core component of the BBSome complex in C. elegans, required for proper intraflagellar transport (IFT) particle assembly and IFT turnaround at the ciliary tip. The BBSome functions as a scaffold to organize IFT-A and IFT-B subcomplexes, ensuring their coordinated movement along ciliary axonemes. BBS-7 is expressed exclusively in ciliated sensory neurons and localizes to the cilium, ciliary basal body, and axoneme where it undergoes bidirectional IFT movement. Loss of BBS-7 function results in dissociation of IFT-A and IFT-B subcomplexes during anterograde transport, ciliary structural defects, compromised chemotaxis, and impaired localization of ciliary membrane proteins including guanylyl cyclases and mechanosensory receptors.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008104 intracellular protein localization | IBA GO_REF:0000033 | MODIFY | Summary: BBS-7 as part of the BBSome is involved in protein localization, specifically the targeting and transport of ciliary membrane proteins. The BBSome controls IFT assembly and turnaround, regulating protein cargo loading and transport (PMID:22922713). Reason: While the annotation captures BBS-7's role in protein localization, this term is too general. The more specific function is ciliary protein localization, as BBS-7/BBSome specifically regulates the localization of proteins to and within cilia, including IFT components and ciliary membrane receptors (PMID:22922713, PMID:25335890). Proposed replacements: protein localization to cilium Supporting Evidence: PMID:22922713 the BBSome functions as a scaffold to organize IFT-A, IFT-B, ciliary membrane receptors, ciliary signaling molecules, and/or other IFT cargos into an entire unit and prepare it for IFT transport file:worm/bbs-7/bbs-7-deep-research-falcon.md model: Edison Scientific Literature |
| GO:0016020 membrane | IBA GO_REF:0000033 | MODIFY | Summary: BBS-7 as part of the BBSome is associated with membranes, particularly ciliary membranes. The BBSome shares structural features with COPI, COPII, and clathrin coats, functioning as a coat complex for membrane protein sorting (PMID:22922713). Reason: The term 'membrane' is too general for BBS-7 localization. BBS-7 specifically localizes to the ciliary membrane system and is involved in ciliary membrane protein sorting. A more specific cellular component term reflecting ciliary localization would be more appropriate. Proposed replacements: cilium Supporting Evidence: PMID:22922713 The BBSome also shares the common structural features with COPI, COPII, and clathrin coats, and can directly recognize IFT cargos |
| GO:0034464 BBSome | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-7 is a core component of the BBSome complex. This is well-established across species and confirmed in C. elegans (PMID:22922713, PMID:15231740). The BBSome contains BBS-1, BBS-2, BBS-4, BBS-5, BBS-7, BBS-8, and BBS-9. Reason: This is a well-supported core function. BBS-7 is definitively a BBSome component, confirmed by both phylogenetic analysis (IBA) and direct experimental evidence in C. elegans showing physical interaction with other BBSome subunits. Supporting Evidence: PMID:22922713 fluorescence complementation can be observed in BBS-1βBBS-7 and BBS-1βBBS-9 pair, indicative of the coexistence of these three BBS proteins in the same complex PMID:15231740 mutations in the Caenorhabditis elegans bbs-7 and bbs-8 genes cause structural and functional defects in cilia |
| GO:0036064 ciliary basal body | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-7 localizes to the ciliary basal body where it participates in IFT particle assembly before anterograde transport. The BBSome assembles IFT complexes at the ciliary base (PMID:22922713, PMID:15231740). Reason: Well-supported localization. BBS-7 and other BBSome proteins localize predominantly at the base of cilia (basal body) where they function in IFT assembly. This is confirmed by direct experimental observation in C. elegans. Supporting Evidence: PMID:15231740 C. elegans BBS proteins localize predominantly at the base of cilia PMID:22922713 the BBSome is required for assembling IFT particles at both ciliary base and tip |
| GO:0043005 neuron projection | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-7 is expressed in ciliated sensory neurons in C. elegans, localizing to their ciliary projections including amphid, labial, and phasmid neurons (PMID:14520415, PMID:15231740). Reason: Accurate localization. BBS-7 is specifically expressed in ciliated sensory neurons and localizes to their projections (the sensory cilia). However, the more specific term 'cilium' or 'sensory cilium' would be preferred. Supporting Evidence: PMID:14520415 all available Caenorhabditis elegans BBS homologues are expressed exclusively in ciliated neurons |
| GO:0060271 cilium assembly | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-7 is required for proper cilium assembly through its role in IFT. Loss of BBS-7 results in structural ciliary defects including loss of distal segments (PMID:15231740, PMID:17000880). Reason: Core function. BBS-7 is essential for proper cilia biogenesis through its role in IFT particle assembly and maintaining IFT integrity. This is supported by strong experimental evidence showing ciliary structural defects in bbs-7 mutants. Supporting Evidence: PMID:15231740 mutations in the Caenorhabditis elegans bbs-7 and bbs-8 genes cause structural and functional defects in cilia PMID:17000880 the loss of BBS-7 and -8 function in mutant animals leads to the loss of ciliary distal segments and sensory defects |
| GO:0005930 axoneme | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-7 localizes to the ciliary axoneme where it undergoes bidirectional IFT movement (PMID:15231740). The protein moves in anterograde and retrograde directions along the ciliary axonemes. Reason: Well-supported localization. BBS-7 is found in the axoneme where it participates in IFT. UniProt confirms BBS-7 moves bidirectionally along the ciliary axonemes. Supporting Evidence: PMID:15231740 like proteins involved in intraflagellar transport (IFT), a process necessary for cilia biogenesis and maintenance, move bidirectionally along the ciliary axoneme |
| GO:0005929 cilium | IEA GO_REF:0000044 | ACCEPT | Summary: IEA annotation based on UniProt subcellular location. BBS-7 localizes to cilia as part of the BBSome complex, participating in IFT. Reason: Correct annotation, well-supported by multiple experimental studies. BBS-7 is a ciliary protein that functions within cilia. Supporting Evidence: PMID:15231740 C. elegans BBS proteins localize predominantly at the base of cilia |
| GO:0005930 axoneme | IEA GO_REF:0000044 | ACCEPT | Summary: IEA annotation based on UniProt subcellular location. BBS-7 localizes to the axoneme as part of IFT. Reason: Correct annotation consistent with experimental evidence showing BBS-7 moves along the ciliary axoneme during IFT. Supporting Evidence: PMID:15231740 move bidirectionally along the ciliary axoneme |
| GO:0015031 protein transport | IEA GO_REF:0000043 | ACCEPT | Summary: IEA annotation based on UniProt keyword. BBS-7 is involved in protein transport through its role in IFT. Reason: Correct general annotation. BBS-7 participates in ciliary protein transport as part of the IFT machinery. The BBSome loads protein cargos for IFT transport. Supporting Evidence: PMID:22922713 the BBSome functions as a scaffold to organize IFT-A, IFT-B, ciliary membrane receptors, ciliary signaling molecules, and/or other IFT cargos into an entire unit and prepare it for IFT transport |
| GO:0030030 cell projection organization | IEA GO_REF:0000043 | ACCEPT | Summary: IEA annotation based on UniProt keyword. BBS-7 is involved in cilium organization through its role in IFT and cilium biogenesis. Reason: Correct general annotation. BBS-7 is required for proper organization of cilia (a type of cell projection) through its role in IFT. Supporting Evidence: PMID:15231740 mutations in the Caenorhabditis elegans bbs-7 and bbs-8 genes cause structural and functional defects in cilia |
| GO:0034464 BBSome | IEA GO_REF:0000002 | ACCEPT | Summary: IEA annotation based on InterPro domain. BBS-7 is a BBSome component as indicated by its conserved domain structure. Reason: Correct annotation consistent with IBA and experimental evidence. Retaining both IEA and IBA annotations is appropriate as they derive from independent evidence sources. Supporting Evidence: PMID:22922713 fluorescence complementation can be observed in BBS-1βBBS-7 and BBS-1βBBS-9 pair |
| GO:1905515 non-motile cilium assembly | IEA GO_REF:0000002 | ACCEPT | Summary: IEA annotation based on InterPro. C. elegans sensory cilia are non-motile (primary) cilia, and BBS-7 is required for their assembly. Reason: Appropriate annotation. C. elegans sensory neurons have non-motile (primary) cilia, and BBS-7 is required for their proper assembly. This is more specific than the general 'cilium assembly' term. Supporting Evidence: PMID:15231740 mutations in the Caenorhabditis elegans bbs-7 and bbs-8 genes cause structural and functional defects in cilia |
| GO:0005929 cilium | NAS PMID:22922713 The BBSome controls IFT assembly and turnaround in cilia. | ACCEPT | Summary: NAS annotation from ComplexPortal based on Wei et al. 2012 showing BBSome localization and function in cilia. Reason: Correct annotation. PMID:22922713 extensively characterizes BBS-7 and BBSome localization and function in C. elegans cilia. Supporting Evidence: PMID:22922713 the BBSome is required for assembling IFT particles at both ciliary base and tip |
| GO:0060271 cilium assembly | NAS PMID:22922713 The BBSome controls IFT assembly and turnaround in cilia. | ACCEPT | Summary: NAS annotation from ComplexPortal. The BBSome is required for proper cilium assembly through its role in IFT. Reason: Correct annotation supported by the cited publication showing BBSome role in IFT assembly and ciliogenesis. Supporting Evidence: PMID:22922713 the major role for the BBSome in cilia is to efficiently assemble IFT particles at both cilia base and tip |
| GO:1904107 protein localization to microvillus membrane | IMP PMID:25335890 Ciliopathy proteins establish a bipartite signaling compartm... | KEEP AS NON CORE | Summary: This annotation refers to BBS-7's role in localizing guanylyl cyclases to the 'finger compartment' of AFD thermosensory neurons, which contains microvillus-like structures (PMID:25335890). Reason: This is a specialized function in AFD thermosensory neurons rather than a core function. While experimentally validated, it represents a specific neuronal context. The finger compartment of AFD neurons contains microvillus-like structures where guanylyl cyclases localize. BBS-7 mutants show impaired localization of GCY-8, GCY-18, and GCY-23 to this region. Supporting Evidence: PMID:25335890 requires BBS-8 and DAF-25 (known as Ankmy2 in mammals) for correct localization of guanylyl cyclases needed for thermosensation |
| GO:0097730 non-motile cilium | IDA PMID:22342749 Endocytosis genes facilitate protein and membrane transport ... | ACCEPT | Summary: IDA annotation showing BBS-7 localization to non-motile (sensory) cilia in C. elegans based on imaging studies. Reason: Correct and specific localization annotation. C. elegans sensory cilia are non-motile primary cilia, and BBS-7 localizes to these structures. Supporting Evidence: PMID:15231740 C. elegans BBS proteins localize predominantly at the base of cilia |
| GO:0036064 ciliary basal body | IDA PMID:22922713 The BBSome controls IFT assembly and turnaround in cilia. | ACCEPT | Summary: IDA annotation showing BBS-7 localization to the ciliary basal body. Wei et al. 2012 showed BBSome proteins accumulate around the ciliary base. Reason: Well-supported localization. The BBSome assembles IFT complexes at the ciliary base (basal body region) before anterograde transport begins. Supporting Evidence: PMID:22922713 Like in dyf-2(jhu616) animals, all BBSome proteins strongly accumulate around the ciliary base PMID:15231740 C. elegans BBS proteins localize predominantly at the base of cilia |
| GO:0042073 intraciliary transport | IMP PMID:17000880 Mechanism of transport of IFT particles in C. elegans cilia ... | ACCEPT | Summary: IMP annotation based on mutant phenotype showing BBS-7 role in IFT. Loss of BBS-7 causes IFT-A and IFT-B subcomplexes to dissociate and move at different rates (PMID:17000880, PMID:22922713). Reason: Core function. BBS-7 is essential for proper IFT through its role in maintaining IFT particle integrity and regulating IFT assembly and turnaround. Supporting Evidence: PMID:17000880 in bbs-7/-8 mutants, kinesin-II and IFT-A move together at 0.5 ΞΌm/s, but OSM-3βkinesin and IFT-B move as a distinct complex at 1.3 ΞΌm/s PMID:22922713 the BBSome is required for assembling IFT particles at both ciliary base and tip |
| GO:0043005 neuron projection | IDA PMID:14520415 Basal body dysfunction is a likely cause of pleiotropic Bard... | ACCEPT | Summary: IDA annotation showing BBS-7 expression in ciliated sensory neuron projections (PMID:14520415). Reason: Correct localization. BBS-7 is expressed in ciliated sensory neurons and localizes to their ciliary projections. Supporting Evidence: PMID:14520415 all available Caenorhabditis elegans BBS homologues are expressed exclusively in ciliated neurons, and contain regulatory elements for RFX, a transcription factor that modulates the expression of genes associated with ciliogenesis and intraflagellar transport |
| GO:1905515 non-motile cilium assembly | IEP PMID:14520415 Basal body dysfunction is a likely cause of pleiotropic Bard... | ACCEPT | Summary: IEP annotation based on expression pattern. BBS-7 is expressed in ciliated neurons suggesting role in cilium assembly. Reason: Appropriate annotation. Expression in ciliated neurons combined with ciliopathy phenotypes in mutants supports a role in non-motile cilium assembly. Supporting Evidence: PMID:14520415 all available Caenorhabditis elegans BBS homologues are expressed exclusively in ciliated neurons, and contain regulatory elements for RFX, a transcription factor that modulates the expression of genes associated with ciliogenesis and intraflagellar transport |
| GO:0060271 cilium assembly | IMP PMID:15231740 Loss of C. elegans BBS-7 and BBS-8 protein function results ... | ACCEPT | Summary: IMP annotation based on mutant phenotype. bbs-7 mutants have structural ciliary defects including loss of distal segments (PMID:15231740). Reason: Core function with strong experimental support. Loss of BBS-7 causes structural and functional ciliary defects demonstrating its requirement for proper cilium assembly. Supporting Evidence: PMID:15231740 mutations in the Caenorhabditis elegans bbs-7 and bbs-8 genes cause structural and functional defects in cilia |
| GO:0006935 chemotaxis | IMP PMID:15231740 Loss of C. elegans BBS-7 and BBS-8 protein function results ... | KEEP AS NON CORE | Summary: IMP annotation based on mutant phenotype. bbs-7 mutants exhibit defective chemotaxis behavior (PMID:15231740). Reason: Secondary phenotype. Chemotaxis defects are a consequence of ciliary dysfunction rather than a direct molecular function of BBS-7. BBS-7's core function is in IFT/BBSome, and chemotaxis defects result from impaired sensory cilium function. Supporting Evidence: PMID:15231740 mutations in the Caenorhabditis elegans bbs-7 and bbs-8 genes cause structural and functional defects in cilia |
| GO:0042073 intraciliary transport | IMP PMID:15231740 Loss of C. elegans BBS-7 and BBS-8 protein function results ... | ACCEPT | Summary: IMP annotation based on mutant phenotype. bbs-7 mutants have compromised IFT with dissociation of IFT-A and IFT-B subcomplexes (PMID:15231740). Reason: Core function. BBS-7 is required for proper IFT including maintenance of IFT particle integrity during transport. Loss of BBS-7 causes IFT-A and IFT-B to move separately. Supporting Evidence: PMID:15231740 BBS-7 and BBS-8 are required for the normal localization/motility of the IFT proteins OSM-5/Polaris and CHE-11, and to a notably lesser extent, CHE-2 |
| GO:0005198 structural molecule activity | NAS | NEW | Summary: Added to align core_functions with existing annotations. Reason: Core function term not present in existing_annotations. |
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Q: Does BBS-7 have BBSome-independent functions?
Q: How does BBS-7 interact with specific cargo proteins?
Experiment: Structure determination of the C. elegans BBSome complex to understand BBS-7's position
Experiment: Cargo-specific binding assays to identify direct BBS-7 interacting partners
Experiment: Tissue-specific rescue experiments to identify neuron-specific BBS-7 functions
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