Cytoplasmic protein involved in the delivery of the dynein machinery to the motile cilium. It is required for the assembly of the axonemal dynein inner and outer arms, two structures attached to the peripheral outer doublet A microtubule of the axoneme, that play a crucial role in cilium motility. Interacts with DNAI2; probably involved in outer arm dynein assembly. Observed only in the cytoplasm of ciliated cells and absent from cilia. Belongs to the DNAAF5 family.