Component of the intraflagellar transport (IFT) complex B: together with IFT81, forms a tubulin-binding module that specifically mediates transport of tubulin within the cilium. Binds beta-tubulin via its basic region. Required for ciliogenesis. 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 IFT81; the interaction is direct: within the IFT complex B, IFT74 and IFT81 mediate the transport of tubulin within the cilium. Interacts (via basic region) with beta-tubulin (via acidic region); interaction is direct. Belongs to the IFT74 family.