Component of the intraflagellar transport (IFT) complex B required for transport of proteins in the motile cilium. Required for transport of specific ciliary cargo proteins related to motility, while it is neither required for IFT complex B assembly or motion nor for cilium assembly. Plays a key role in maintaining the integrity of the IFT complex B and the proper ciliary localization of the IFT complex B components. Essential for maintaining proper microtubule organization within the ciliary axoneme (By similarity). Component of the IFT complex B. Defective cilia (PubMed:22718903, PubMed:24596149). Morpholino knockdown of the protein results in cilia defects in the pronephric kidney at 27 hpf and distension/dilation of pronephros at 5 dpf. In the eyes, the outer segments of photoreceptor cells appear shortened or absent, whereas cellular lamination seems normal in retinas at 5 dpf (PubMed:22718903). Left-right asymmetry defects with abnormal heart looping, hydrocephalus, pronephric cysts, abnormal ear otolith formation and curly body axis (PubMed:24596149). Belongs to the IFT56 family.