Fig. 4. Phylogenetic relationships of CionaKv4 and CionaKChIP. (A) Phylogenetic relationships of Kv4 channels from different species. Two cnidarian Kv4 channels were used as an out-group to polarize the relationships of the other channels. The two arthropod channels, Fly Shal and Lobster Shal, group together as a sister group to the chordate channels. Shal and Ciona are indicated in bold type. The two tunicate channels, from Halocynthia roretzi and Ciona intestinalis, group together and are basal to the clade containing all three paralogues of the vertebrates. All of the vertebrate channels group within one of three paralogous clades, indicating that the three vertebrate Kv4 paralogues were present in the common ancestor of all vertebrates, but not in the common ancestor of vertebrates and tunicates. (B) Phylogenetic relationships of KChIPs from different species. Two arthropod KChIPs that were found in BLAST searches of the genomes of Drosophila (fly) and Anopheles gambiae (mosquito) were used as an out-group to polarize the relationships of the other KChIPs. Numbers above or below the lines indicate Bayesian posterior probability, calculated with the MrBayes program. Unlabelled nodes have a posterior probability of 1. GenPept. accession numbers of the protein sequences are indicated in parentheses. The scale bars represent a divergence equivalent to an average of a 10% change in amino acids.