ARMC9 localizes near the ends of B-tubules. (A) An SR-SIM immunofluorescence image of ARMC9A-mNeon-6xMyc. The cell was labeled with polyG tubulin (green) and anti-Myc (red) antibodies (bars: 20 µm [main], 10 µm [inset]). ARMC9A is associated with the tips of mature full-length cilia; the graph shows the average fluorescence intensity along the cilium length (error bars show standard deviations, n = 3 cilia; A.U., arbitrary units). (B) SR-SIM images of isolated cilia (of cells expressing ARMC9A-mNeon-6xMyc) that have partially splayed microtubules (red, polyG tubulin; green, 6xMyc). (C and D) Immunogold TEM localization of ARMC9A in cilia of wild-type (C) and ARMC9A-mNeon-6xMyc expressing cells (D) using an anti-Myc primary antibody. The red circles mark the gold particles on the axonemes. The red dots on the right side summarize the distribution of gold particles at these approximate positions in a total of 18 cilia per genotype. The blue arrows mark the proximal boundary of distal segment and the As mark the termination points of identifiable A-tubule ends (note that some of these ends could be on the nonimaged side of the axoneme or were lost during preparation (bars, 200 nm). (E) An SR-SIM image of a cell expressing ARMC9-2xmNeon-6xMyc labeled with anti-Myc (red) and polyE (green) antibodies. ARMC9B is associated with the tips of assembling cilia. The box marks growing cilia of the assembling new oral apparatus (bars: 20 µm [main]; 10 µm [inset]). (F) An SR-SIM image of a portion of a Tetrahymena cell coexpressing MTT1-driven GFP-FAP256A (green, GFP) and ARMC9A-mNeon-6xMyc (red, 6xMyc; the brackets connect the FAP256 and ARMC9 signals on the same cilia; bar, 5 µm).