As part of MIA, a complex associated with the outer doublet microtubules of the axoneme, may play a role in ciliary/flagellar motility by regulating the assembly and the activity of axonemal inner dynein arm. Interacts with FAP73; form the modifier of inner arm (MIA) complex. Localizes to the outer doublet microtubules of the axoneme. The mia1-1, mia1-2, mia1-3 and mia1-4 mutants do not express the protein in the axoneme and display slightly jerky, slow swimming phenotypes, reduced flagellar beat frequencies and defective phototaxis. Belongs to the CFAP100 family.