| Functional category | Role of BBS-9/BBSome in *C. elegans* | Mechanistic summary | Key evidence source |
|---|---|---|---|
| IFT assembly at ciliary base | BBS-9 functions as part of the BBSome that assembles IFT machinery at the ciliary base | The BBSome organizes IFT-A, IFT-B, and kinesin motors into a functional anterograde transport complex at the ciliary base; structural work places BBS9 as a central hub subunit that helps stabilize BBSome architecture needed for this assembly function (pqac-00000020, pqac-00000023, pqac-00000001, pqac-00000003) | Wei et al. 2012; Singh et al. 2020; Nakayama and Katoh 2018 |
| IFT turnaround regulation at ciliary tip | BBS-9/BBSome is required for proper IFT particle remodeling and recycling at the ciliary tip | In BBSome-defective worms, IFT-B accumulates at the tip while IFT-A can continue moving, indicating failure of tip reorganization and retrograde turnaround; the BBSome works with DYF-2 to reassemble transport complexes after anterograde arrival (pqac-00000023, pqac-00000024, pqac-00000025, pqac-00000026) | Wei et al. 2012 |
| Ciliary membrane protein trafficking/removal | BBS-9 participates in the BBSome’s adaptor role for ciliary membrane protein export/removal | The BBSome rides with IFT trains and acts mainly as a cargo adaptor for removing selected membrane-associated proteins from cilia; ARL6/BBS3-GTP recruits and activates the BBSome for membrane engagement and cargo recognition (pqac-00000008, pqac-00000022, pqac-00000027, pqac-00000028, pqac-00000031) | Akella et al. 2020; Wingfield et al. 2018; Singh et al. 2020 |
| Degradative sorting of sensory receptors | BBS-9/BBSome supports lysosome-directed removal of ciliary sensory receptors | Work in worms shows the BBSome promotes degradative sorting of receptors such as PKD-2, ODR-10, and OSM-9; when BBSome function is compromised, these receptors accumulate abnormally in cilia and near the ciliary base, indicating defective lysosomal routing rather than defective entry (pqac-00000009, pqac-00000011, pqac-00000013) | Xu et al. 2015 |
| Extracellular vesicle regulation | BBS-9/BBSome negatively regulates EV shedding from sensory cilia | In BBSome mutants, EVs accumulate ectopically at the ciliary base/lumen and sensory compartments become enlarged, indicating that the BBSome normally restrains ciliary EV production or release and helps maintain sensory organ morphology, partly with RAB-28 (pqac-00000006, pqac-00000008, pqac-00000010, pqac-00000012) | Akella et al. 2020 |
| Sensory neuron function | BBS-9/BBSome is required for normal sensory cilium integrity and signaling outputs | Loss of BBSome function causes shortened or structurally abnormal cilia, dye-filling defects, and impaired chemosensory/osmosensory behaviors; receptor mislocalization and defective IFT likely underlie these sensory phenotypes (pqac-00000007, pqac-00000011, pqac-00000014, pqac-00000015, pqac-00000016) | Wingfield et al. 2018; Xu et al. 2015; Veleri et al. 2012 |


*Table: This table summarizes the main experimentally supported functions of BBS-9 as a core BBSome component relevant to ciliary transport and sensory signaling in *C. elegans*. It is useful for linking molecular mechanism to cellular phenotypes across the best-supported functional categories.*