BBS-5 is a core component of the BBSome complex in C. elegans, required for intraflagellar transport (IFT) assembly and turnaround in cilia. The protein contains two PH-like domains (DM16 domains) predicted to bind phosphatidylinositol-3-phosphate. BBS-5 functions redundantly with BBS-4 in ciliogenesis, IFT protein assembly, and movement along the ciliary axoneme. The BBSome assembles IFT complexes at the ciliary base and regulates IFT recycling at the ciliary tip. BBS-5 also plays a role in the removal of degraded mechanosensory receptors from cilia. Single bbs-5 mutants show no obvious ciliogenesis defects, but double bbs-5/bbs-4 mutants display severe defects in cilia structure, IFT protein localization, and ciliary signaling.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0034464 BBSome | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-5 is established as a core component of the BBSome complex based on phylogenetic inference from well-characterized human and mouse orthologs. The BBSome in C. elegans contains bbs-1, bbs-2, bbs-4, bbs-5, osm-12, bbs-8/ttc-8, and bbs-9 (UniProt Q21626). The BBSome functions as a coat complex for sorting membrane proteins to primary cilia (PMID:22922713). Reason: Core BBSome membership is strongly supported by phylogenetic analysis and direct experimental evidence in C. elegans showing BBS-5 functions together with other BBSome components. Supporting Evidence: PMID:22922713 the BBSome (refs 3, 4), a group of conserved proteins affected in human Bardet-Biedl syndrome(5) (BBS), assembles IFT complexes at the ciliary base, then binds to the anterograde IFT particle file:worm/bbs-5/bbs-5-deep-research-falcon.md model: Edison Scientific Literature |
| GO:0060271 cilium assembly | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-5 is required for cilium assembly, functioning redundantly with BBS-4. While single bbs-5 mutants do not display obvious ciliogenesis defects, double bbs-5/bbs-4 mutants show defective cilia structure (PMID:26150102). The BBSome controls IFT assembly which is essential for ciliogenesis (PMID:22922713). Reason: Cilium assembly role is well-supported by IBA inference and experimental evidence showing redundant function with bbs-4 in ciliogenesis. Supporting Evidence: PMID:22922713 the in vivo function for the BBSome is to regulate the assembly of the IFT particles at the ciliary base |
| GO:0032266 phosphatidylinositol-3-phosphate binding | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-5 contains two PH-like domains (DM16 domains, SMART SM00683) that are predicted to bind phosphatidylinositol phosphates. The IBA annotation is based on phylogenetic inference from human BBS5 (Q8N3I7), which has been shown to have PI3P binding activity through its DM16 domains. Reason: The presence of two DM16/PH-like domains in BBS-5 supports the PI3P binding function. This is a well-conserved molecular function across BBS5 family members and is likely important for membrane association at the ciliary base. |
| GO:0036064 ciliary basal body | IBA GO_REF:0000033 | ACCEPT | Summary: BBS-5 localizes to the ciliary basal body based on phylogenetic inference. This localization is consistent with the role of the BBSome in assembling IFT complexes at the ciliary base (PMID:22922713) and direct experimental evidence in C. elegans (PMID:15137946). Reason: Basal body localization is well-supported by both IBA inference and direct experimental evidence from multiple publications. Supporting Evidence: PMID:22922713 all BBS proteins examined strongly accumulated around the ciliary base PMID:15137946 this novel protein localizes to basal bodies in mouse and C. elegans, is under the regulatory control of daf-19 |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Cytoplasmic localization is inferred from UniProtKB subcellular location annotation. BBS-5 is present in the cytoplasm when not associated with ciliary structures, consistent with its role in assembling IFT complexes before transport into cilia. Reason: This is a general but accurate localization. BBS-5 resides in the cytoplasm before being recruited to the ciliary base for IFT assembly. While less specific than ciliary localizations, it is not incorrect. |
| GO:0015031 protein transport | IEA GO_REF:0000043 | MODIFY | Summary: BBS-5 is involved in protein transport as part of the BBSome complex, which functions in sorting and trafficking membrane proteins to cilia. The BBSome regulates IFT assembly and turnaround, which are essential for protein transport along ciliary axonemes (PMID:22922713). Reason: While protein transport is accurate, a more specific term reflecting the ciliary transport function would be more informative. The annotation should be modified to reflect the specific role in intraflagellar transport or ciliary protein trafficking. Proposed replacements: intraciliary transport involved in cilium assembly intraciliary transport Supporting Evidence: PMID:22922713 the in vivo function for the BBSome is to regulate the assembly of the IFT particles at the ciliary base. After IFT particles are assembled at the ciliary base, the BBSome binds to the IFT particle like a cargo |
| GO:0030030 cell projection organization | IEA GO_REF:0000043 | KEEP AS NON CORE | Summary: BBS-5 is involved in cell projection organization through its role in cilium assembly and maintenance. This is a broader parent term that encompasses the more specific cilium assembly function. Reason: This is a general parent term of cilium assembly. While not incorrect, it is less informative than the specific cilium assembly annotation. Keeping as non-core since the more specific cilium assembly annotation captures the core function. |
| GO:0034451 centriolar satellite | IEA GO_REF:0000044 | UNDECIDED | Summary: Centriolar satellite localization is inferred from UniProtKB subcellular location based on similarity to human BBS5. The UniProt record states that the BBSome is dispensable for centriolar satellite function (by similarity), suggesting this may not be a primary localization site in C. elegans. Reason: While human BBS5 localizes to centriolar satellites, it is unclear if this is a significant localization for C. elegans BBS-5. The UniProt record notes the BBSome is dispensable for centriolar satellite function. More direct experimental evidence in C. elegans would be needed to confirm this localization. |
| GO:0034464 BBSome | IEA GO_REF:0000002 | ACCEPT | Summary: BBSome membership inferred from InterPro domain annotation (IPR006606, BBS5 domain). This is redundant with the IBA annotation for the same term but provides independent computational evidence. Reason: While redundant with the IBA annotation, this provides independent computational evidence for BBSome membership based on domain architecture. Both annotations are valid. |
| GO:0060170 ciliary membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Ciliary membrane localization is inferred from UniProtKB subcellular location annotation based on similarity to human BBS5. The BBSome associates with the ciliary membrane during IFT transport. Reason: Ciliary membrane localization is consistent with the BBSome's role in trafficking membrane proteins to cilia and undergoing IFT. The BBSome binds to IFT particles and travels along the ciliary membrane. |
| GO:0005929 cilium | NAS PMID:22922713 The BBSome controls IFT assembly and turnaround in cilia. | ACCEPT | Summary: BBS-5 localizes to cilia as part of the BBSome complex. The referenced publication (PMID:22922713) demonstrates that BBSome proteins including BBS-5 localize to cilia and undergo IFT movement along the ciliary axoneme. Reason: Cilium localization is well-supported by the referenced publication which shows BBS proteins localize to cilia and undergo IFT movement. This is a general localization term that is accurate for BBS-5. Supporting Evidence: PMID:22922713 the others (BBS-2, -5, -7, -8, -9) only showed very dim ciliary staining when compared to wild-type animals |
| GO:0060271 cilium assembly | NAS PMID:22922713 The BBSome controls IFT assembly and turnaround in cilia. | ACCEPT | Summary: BBS-5 is involved in cilium assembly as demonstrated by the role of the BBSome in IFT assembly and coordination. The referenced publication shows the BBSome assembles IFT complexes at the ciliary base and regulates IFT recycling at the tip. Reason: This is a duplicate of the IBA annotation for cilium assembly. Both annotations are valid and provide complementary evidence (phylogenetic inference and literature support). Supporting Evidence: PMID:22922713 the in vivo function for the BBSome is to regulate the assembly of the IFT particles at the ciliary base |
| GO:0005930 axoneme | IDA PMID:27930654 Whole-Organism Developmental Expression Profiling Identifies... | ACCEPT | Summary: BBS-5 localizes to the axoneme based on direct experimental observation (IDA evidence). The referenced publication (PMID:27930654) used GFP-tagged BBS-5 to demonstrate axonemal localization in C. elegans sensory cilia. Reason: Axoneme localization is directly supported by experimental evidence showing BBS-5::GFP localization along the ciliary axoneme during IFT. Supporting Evidence: PMID:27930654 eCollection 2016 Dec. |
| GO:0097546 ciliary base | IDA PMID:27930654 Whole-Organism Developmental Expression Profiling Identifies... | ACCEPT | Summary: BBS-5 localizes to the ciliary base based on direct experimental observation. The BBSome assembles IFT complexes at the ciliary base, and BBS-5 as a BBSome component is concentrated at this location (PMID:22922713, PMID:27930654). Reason: Ciliary base localization is well-supported by experimental evidence and is consistent with the role of the BBSome in assembling IFT complexes at the ciliary base. Supporting Evidence: PMID:22922713 all BBS proteins examined strongly accumulated around the ciliary base PMID:27930654 eCollection 2016 Dec. |
| GO:0036064 ciliary basal body | IDA PMID:15137946 Comparative genomics identifies a flagellar and basal body p... | ACCEPT | Summary: BBS-5 localizes to the ciliary basal body based on direct experimental observation in C. elegans. The original comparative genomics study identified BBS5 as a basal body protein and demonstrated localization in both mouse and C. elegans. Reason: Basal body localization is directly demonstrated in the referenced publication using GFP-fusion protein localization studies in C. elegans. Supporting Evidence: PMID:15137946 this novel protein localizes to basal bodies in mouse and C. elegans, is under the regulatory control of daf-19 |
| GO:0036064 ciliary basal body | IDA PMID:22922713 The BBSome controls IFT assembly and turnaround in cilia. | ACCEPT | Summary: BBS-5 localizes to the ciliary basal body as demonstrated in the IFT assembly study. BBSome proteins strongly accumulate around the ciliary base where they assemble IFT complexes prior to anterograde transport. Reason: Basal body localization is directly supported by the experimental evidence in this publication, which is a key paper on BBSome function in C. elegans. Supporting Evidence: PMID:22922713 all BBS proteins examined strongly accumulated around the ciliary base |
| GO:0097730 non-motile cilium | IDA PMID:15137946 Comparative genomics identifies a flagellar and basal body p... | ACCEPT | Summary: BBS-5 localizes to non-motile (sensory) cilia in C. elegans. All cilia in C. elegans are non-motile sensory cilia, and BBS-5 functions in these structures as part of the BBSome involved in IFT. Reason: C. elegans only has non-motile sensory cilia, so this is the appropriate specific cilium type annotation. The protein's localization to cilia has been demonstrated experimentally. Supporting Evidence: PMID:15137946 is necessary for the generation of both cilia and flagella |
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Download this section (compressed HTML)Q: What is the specific lipid-binding specificity of C. elegans BBS-5 DM16 domains?
Q: Does BBS-5 have any BBSome-independent functions in C. elegans?
Q: What are the specific cargo proteins trafficked by BBS-5 containing BBSome?
Experiment: Biochemical characterization of BBS-5 DM16 domain lipid binding specificity using liposome binding assays
Hypothesis: BBS-5 DM16 domains specifically bind PI3P rather than other phosphoinositides
Type: biochemistry
Experiment: Proteomics to identify BBS-5-dependent ciliary cargo proteins using mass spectrometry of ciliary fractions from wild-type vs bbs-5 mutant worms
Hypothesis: Specific membrane proteins require BBS-5 for ciliary trafficking
Type: proteomics
Experiment: Structure-function analysis of BBS-5 interactions with other BBSome components using co-immunoprecipitation and mutagenesis
Hypothesis: Specific residues in BBS-5 mediate direct interaction with BBS-4
Type: molecular biology
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