Functions in regulating protein trafficking, retinal maintenance and lipid storage (PubMed:23228091, PubMed:23355467, PubMed:24068974, PubMed:26723017). Protects photoreceptor cells R1 to R6 against light-induced retinal degeneration by stimulating norpA-mediated endocytosis of the rhodopsin ninaE (Rh1) (PubMed:23228091). In the auditory receptor neurons, functions as a cilia trafficking regulator of various transient receptor potential (TRP) channel components including iav and nompC (PubMed:24068974, PubMed:26723017). Likely to deliver pre-ciliary vesicles containing membrane proteins such as iav and nompC to the intraflagellar transport complex (IFT) at the cilia base (PubMed:24068974, PubMed:26723017). Plays a role in the inhibition of fat storage (PubMed:23355467). Detected in the cytoplasm and nucleus of the chordotonal neurons (PubMed:12204260, PubMed:24068974). PtdIns 4,5-P2 binds to and regulates its localization to the ciliary base (PubMed:26723017). In the dark, localizes mainly to the rhabdomere domain of photoreceptor cells R1 to R6 (PubMed:23228091). When dark-reared flies are moved into the light, the protein translocates to the cytoplasm (PubMed:23228091). Under normal conditions (12 hr light/12 hr dark), localized mainly in the nucleus of photoreceptor cells with minor staining in the cytoplasm (PubMed:23228091). Detected in sensory neurons which have a ciliary structure such as the chordotonal neurons, Orco-expressing olfactory receptor neurons, labellar gustatory receptor neurons and in the femoral chordotonal organ (at protein level) (PubMed:24068974, PubMed:26723017). In the chordotonal neurons of the Johnston's organ expressed in the proximal to distal cilia, with lower levels of expression in the distal portion (at protein level) (PubMed:24068974). Also detected in the salivary glands and antenna (at protein level) (PubMed:24068974). Expressed in photoreceptor cells (at protein level) (PubMed:23228091). At stage 9 expression is detected in a subset of neuroblasts (PubMed:12204260). By stage 12 expression is found in both the CNS and PNS (PubMed:12204260). In late-stage embryos, expression persists in the CNS and PNS with more abundant expression in the antennal-maxillary sensory neurons and in bilateral groups of cells in the brain (PubMed:12204260). Most abundant at 2-8 hours of embryonic development. The C-terminus is important for mediating light-induced rhodopsin endocytosis. Viable and fertile however flies display a decreased climbing index and extracellular sound-evoked potentials are completely abolished (PubMed:24068974). This hearing defect is likely due to the abnormal localization of the two transient receptor potential channels iav and nompC, as well as eys within the cilia (PubMed:24068974). There is no localization of iav to the proximal cilia, and nompc which is typically found in the distal cilia, is localized to the proximal cilia (PubMed:24068974). Also eys displays a much broader expression pattern (PubMed:24068974). RNAi-mediated knockdown in the fat body of larvae fed a high sugar diet, results in an increase in body weight, an increase in triglyceride accumulation and a decrease in hemolymph glucose levels (PubMed:23355467). Belongs to the TUB family.