Localization of POC1B in Human hTERT-RPE1 Cells
To investigate the effect of the identified POC1B mutations on the subcellular localization of the encoded protein, we synthesized wild-type and variant recombinant POC1B proteins, fused to mRFP, in ciliated hTERT-RPE1 cells. Wild-type POC1B localization was concentrated at the ciliary basal body, as indicated by costaining with the anti-polyglutamylated tubulin antibody GT335, although some diffuse cytoplasmic localization was also observed (Figure 3A; Figure S2A). This confirms previous results of Venoux et al.20 In contrast, variant POC1B proteins, carrying either the p.Gln67del (Figure 3B; Figure S2B) or the p.Arg106Pro (Figure 3C; Figure S2C) amino acid change, completely lost their ciliary localization.