Component of the intraflagellar transport (IFT) complex B. Forms a subcomplex within the IFT complex B with IFT27. Component of the IFT complex B, the core composed of IFT25, IFT27, IFT46, IFT52, IFT74, IFT81 and IFT88 as well as associated subunits IFT20, IFT57, IFT80 and IFT172. Interacts with IFT27; the interaction is direct. Colocalizes with IFT27 at the distal-most portion of basal bodies, probably the transition zones, and concentrates in the basal body region. Phosphorylated. Belongs to the IFT25 family. Was initially classified as a member of the small heat shock family protein. However, it was later shown that it is not the case (PubMed:21505417).