Loss of SPATA7 leads to exclusion of its interacting proteins from the distal region of CC. (a) Retinal cryosections (P15) were costained for SPATA7 (green) and acetylated α-tubulin (red) marking the entire CC of photoreceptors and ∼0.2 µm of the outer segment (OS). Single-cilium image shows localization of SPATA7 throughout the length of the CC. Bar, 10 µm. ONL, outer nuclear layer. (b and d) Immunofluorescence of retinal cryosections (P15) displaying localization of AHI1, NPHP1, NPHP4, RPGRIP1, and RPGR (green) at the CC marked by acetylated α-tubulin (red) in a WT (b) and Spata7 mutant background (d). Representative single-cilium images display localization of the protein signal at the base of CC in the Spata7 mutant (fourth column) in comparison with CC-wide localization in the WT retina (second column). Bars: (main images) 5 µm; (single-cilium images) 1 µm. (c) Model depicting the DCC and PCC within the CC of photoreceptor outer segments. (e) Box plots displaying IQRs of localization signal length for 20 cilia/protein in WT and Spata7 mutant retinae across three repeats (*, P < 0.0001; unpaired t test). The whiskers extend to data points that were <1.5× IQR away from first/third quartiles. (f) Representative 2D STORM reconstruction of the CC displaying AHI1 (green) and acetylated α-tubulin (red) in the WT (top) and Spata7 mutant retina (bottom). The intensity of individual fluorophores was plotted along the length of the CC to determine the length of overlap between AHI1 signal and CC (rightmost panel). Bars, 200 nm.