| Property | Description |
|---|---|
| Gene names and aliases | **dyf-13** in *Caenorhabditis elegans*; orthologous/alias names include **TTC26**, **IFT56**, and **PIFTC3**. Literature explicitly equates TTC26/DYF13/IFT56 across ciliated organisms, validating that the requested gene identity matches the UniProt entry for the worm dyf-13 protein (pqac-00000000, pqac-00000013, pqac-00000043). |
| Organism | The target gene/protein is from ***Caenorhabditis elegans***, where it functions in sensory cilia of amphid and phasmid neurons; cross-species functional data are available from zebrafish, mouse, mammalian cultured cells, and *Chlamydomonas* ortholog studies (pqac-00000020, pqac-00000029, pqac-00000043). |
| Protein family | DYF-13 belongs to the conserved **IFT56/TTC26 family**, a cilia-associated family present in ciliated organisms and absent from non-ciliated organisms, consistent with a dedicated role in intraflagellar transport and ciliary biology (pqac-00000005, pqac-00000003, pqac-00000043). |
| Domain structure | UniProt annotates DYF-13/Q95QT8 with **TPR-like helical superfamily** features and **TTC26 / TPR_19** domains, consistent with tetratricopeptide repeat-mediated protein interaction/adaptor functions typical of IFT-associated scaffold proteins; this agrees with the experimentally supported role of IFT56/TTC26 as an IFT-B-associated adaptor rather than an enzyme (pqac-00000027, pqac-00000026). |
| IFT-B subcomplex position | IFT56/TTC26/DYF-13 is a component of **IFT complex B**, specifically placed in the **IFT-B1b subgroup** together with IFT46, IFT52, IFT70, and IFT88. Recent assembly work indicates IFT56 is part of the IFT-B1 branch and is linked through the IFT46-IFT52 module to other IFT-B subcomplexes (pqac-00000009, pqac-00000028). |
| Primary function | The best-supported primary function is as a **cargo-selective IFT-B-associated adapter/regulator**, not a catalytic protein. IFT56/TTC26/DYF-13 is dispensable for basic IFT train assembly/motility in some systems but is required for transport of a subset of ciliary cargoes, especially **motility-related proteins** such as inner dynein arm components, dynein regulatory complex proteins, and central pair-associated factors (pqac-00000001, pqac-00000004, pqac-00000026, pqac-00000027). |
| Subcellular localization | IFT56/TTC26/DYF-13 localizes to **cilia/flagella** and **basal body-associated regions**, with a punctate distribution characteristic of IFT proteins. In mammalian cells it undergoes bidirectional IFT; in zebrafish and photoreceptors, Ttc26 was also observed at the **transition zone**. Reported mammalian transport speeds for TTC26-GFP are ~**1.22 ± 0.17 μm/s anterograde** and **0.92 ± 0.24 μm/s retrograde** (pqac-00000011, pqac-00000012, pqac-00000029, pqac-00000033). |
| Key phenotypes in *C. elegans* | dyf-13 is one of the classic **Dyf (dye-filling defective)** genes required for proper amphid/phasmid sensory cilium function. The Dyf class is associated with failed DiI filling of sensory neurons and abnormal ciliary structure. Prior work cited in later studies indicates **shortened cilia** in *C. elegans* dyf-13 mutants, and dyf-13 has been linked to regulation of OSM-3-kinesin/IFT-B behavior in sensory cilia (pqac-00000020, pqac-00000002, pqac-00000000). |
| Key phenotypes in other organisms | In **zebrafish**, ttc26 knockdown causes shortened or missing photoreceptor outer segments, pronephric cilia defects, kidney duct dilation, body curvature, edema, abnormal fluid flow, and reduced cilia length/number in Kupffer’s vesicle. In **mouse/vertebrate systems**, Ift56 loss causes developmental patterning defects, male sterility, gait abnormalities, shortened/abnormal cilia, and disorganized axonemal microtubules (pqac-00000029, pqac-00000030, pqac-00000031, pqac-00000035, pqac-00000043, pqac-00000023). |
| Signaling pathway involvement | IFT56 is implicated in **cilium-dependent Hedgehog signaling**. In mouse Ift56/hop mutants, cilia form but fail to properly accumulate **Gli2** and **Gli3** at ciliary tips, while Smoothened localization can remain relatively normal; this leads to defective Shh-dependent patterning in limb and neural tube development. Thus, IFT56 supports signaling competence by maintaining IFT-B integrity and ciliary architecture needed for Gli trafficking (pqac-00000042, pqac-00000043, pqac-00000044, pqac-00000046, pqac-00000048). |
| Human disease associations | Human **TTC26/IFT56** has been linked to **severe biliary ciliopathy** by biallelic mutation studies, and broader cross-species work places IFT56 among IFT-B components whose dysfunction can contribute to ciliopathy phenotypes. Although the detailed clinical text was not retrievable here, the paper metadata and abstract identify TTC26 as a human disease gene in severe biliary ciliopathy (pqac-00000023). |


*Table: This table condenses the main verified properties of the C. elegans dyf-13 gene product and its orthologs, including molecular function, localization, phenotypes, and pathway relevance. It is useful as a quick-reference functional annotation summary grounded in the retrieved evidence.*