| Functional aspect | Finding | Evidence type | Reference |
|---|---|---|---|
| Molecular function | XBX-1 is the light intermediate chain of the IFT-dynein (dynein-2) complex and is essential for retrograde intraflagellar transport in *C. elegans* sensory cilia. (pqac-00000001, pqac-00000002, pqac-00000003) | Genetic/biochemical | Hao et al. 2011 |
| Expression pattern | *xbx-1* is expressed in most or all ciliated sensory neurons and is an X-box-regulated ciliome gene under DAF-19/RFX control; more recent work supports cooperative regulation with FKH-8. (pqac-00000005, pqac-00000015, pqac-00000025, pqac-00000027) | Reporter assays, transcription factor analysis | Perrone et al. 2003; Chu et al. 2012; Brocal-Ruiz et al. 2023 |
| Subcellular localization | XBX-1 localizes to ciliary axonemes of amphid and phasmid neurons, visualized with XBX-1::YFP/RFP/tdTomato reporters and knock-ins. (pqac-00000007, pqac-00000008) | XBX-1::YFP/tdTomato imaging | Hao et al. 2011; Scheidel et al. 2018 |
| Transport properties | XBX-1 is transported anterogradely at ~0.776 ± 0.08 µm/s in the middle segment and ~1.30 ± 0.18 µm/s in the distal segment; its movement is largely independent of IFT particle/BBSome coupling. (pqac-00000004, pqac-00000016) | IFT velocity measurements | Hao et al. 2011 |
| Loss-of-function phenotype | *xbx-1(ok279)* and related loss-of-function conditions cause highly abnormal phasmid cilia, dye-filling defects, and short/swollen cilia that accumulate IFT material, consistent with retrograde IFT failure. (pqac-00000002, pqac-00000005, pqac-00000017) | Mutant phenotyping, dye-fill assays, cilia morphology analysis | Hao et al. 2011; Perrone et al. 2003; Williams et al. 2008 |
| Complex membership | XBX-1/DYNC2LI1 forms the DYNC2H1-DYNC2LI1 core dynein-2 subcomplex and bridges the heavy chain tail to intermediate-chain modules in the holocomplex. (pqac-00000009, pqac-00000010, pqac-00000033, pqac-00000034, pqac-00000035) | Structural analysis, cryo-EM, biochemical complex mapping | Qiu et al. 2022; Tsurumi et al. 2019; Hiyamizu et al. 2023 |
| Transcriptional regulation | *xbx-1* is co-regulated by FKH-8 and DAF-19/RFX through nearby FKH-binding and X-box regulatory elements, supporting a cooperative ciliome transcription program. (pqac-00000025, pqac-00000028, pqac-00000031, pqac-00000032) | ChIP-seq, reporter assays, cis-regulatory analysis | Brocal-Ruiz et al. 2023 |
| Human disease relevance | The human ortholog **DYNC2LI1** is implicated in skeletal ciliopathies, including short-rib thoracic dysplasia, and pathogenic variants can impair dynein-2 assembly and ciliary function. (pqac-00000024, pqac-00000000) | Human genetics, cell-based functional studies | Qiu et al. 2022; Open Targets context |


*Table: This table summarizes the main experimentally supported functional findings for *C. elegans xbx-1*, including molecular role, localization, transport behavior, regulation, phenotype, and human ortholog relevance. It is useful as a compact evidence map for the gene’s annotation.*