Phylogenetic relationship between GPCRs in Ciona and other genomes. The figure illustrates the presence of representatives of Glutamate, Rhodopsin, Adhesion, Frizzled, and Secretin family members in Ciona. Two sequences that are homologous to cAMP and Methuselah GPCRs are also represented. The position of the Rhodopsin family was established by including 15 receptors from the Rhodopsin family. The divergent, "Other/Unclassified" GPCRs known to lack reliable homologs from other species or which are fast evolving, are excluded from the final representation. For display reasons bootstrap values are not represented in the figure. Instead, the corresponding tree file in standard Newick format is provided [Additional data file 5]. For Figure 2, and Figures 3, 5 and 6, the multiple sequence alignment was built taking into account terminally truncated TM spanning regions, while the consensus phylogenetic tree was calculated using NJ method on 1000 replicas of the dataset. Ciona GPCR taxons are represented in numerals as per numbering in Additional data file 2. Abbreviations for known GPCRs are as described in [5, 6, 8, 9] and based on Swiss-prot IDs. Ciona GPCRs that deviate from the predicted 7TM structure are marked using a '#' symbol.