The Mia1 and Mia2 proteins form the MIA complex. (A) Anti-FAP100 and -FAP73 antibodies detect bands in wild-type axonemes. Both bands are missing or greatly reduced in mia1, whereas only the FAP73 band is missing in mia2. CBB staining of tubulin from each sample is shown as a loading control. (B) Axonemes from HA-tagged rescued strains (mia1R and mia2R) assemble FAP100 (top) and FAP73 (bottom). The expressed proteins have slower migration as a result of the expression of the 3×HA tags. (C) Immunoprecipitations from mia1R extracts using the anti-HA antibody pull down an ∼76-kD protein (FAP100-HA) and an ∼35-kD protein (FAP73; both indicated by red arrows). Plus and minus signs indicate addition of beads with or without the anti-HA antibody. Immunoblots using the specific antibodies also show that these proteins were precipitated only in the mia1R extracts. (D) The Mia1p (FAP100; top) and Mia2p (FAP73; bottom) domain structures were predicted using the SMART and COILS programs. Both proteins show a high probability of forming coiled-coil domains in the middle part of the protein. The color coding in the structure prediction by SMART analysis: green, regions having a high probability of forming coiled-coil structure; pink, regions of low complexity; gray, areas with no detectable domains. The window width in the structure prediction by COILS version 2.2: green, 14 residues; blue, 21 residues; red, 28 residues. wt, wild type.