Fig. 6. PAR-3 protein localizes to the CAB. (A) Sequence recognized by the PAR-3 antibody. The hatched rectangle represents the region of Drosophila PAR-3 protein (Bazooka) used to raise the PAR-3 antibody (Wodarz et al., 1999). The alignment shows high homology between the first 87 amino acids of this domain and an open reading frame in the Ciona genome. (B) Structure of PAR-3 gene in Ciona genome. The gene covers 20 kb and consists of at least 20 exons, as deduced by comparing conserved coding regions between Ciona intestinalis and Ciona savigny genomes using Vista software. The first three exons (beginning at position 109598) encode the conserved sequence shown in A. The Ciona PAR-3 DNA sequence previously described, which encodes the three PDZ domains (Sasakura et al., 2003) begins 5 kb downstream of the N-terminal homology and reads in the same direction. Numbers below the horizontal line indicate base position on scaffold 159 from version 1.0 of the genome (scaffold 148 in version 1.95). (C) Immunoblot using PAR-3 antibody on protein extract from Phallusia eggs. (D,E) Immunolabelling of Phallusia embryos with PAR-3 antibody. Arrowhead indicates position of the pair of CABs.