Figure 2.

Phylogenetical tree of 33 selected NRs. The six subfamilies are shown. Subfamilies are defined by clusters supported by high robustness “bootstrap” values above 90 starting from the base of the tree, which was rooted at mid-length of its longest path. Ancestral segments for subfamilies 1 to 5 have their bootstrap value boxed. Subfamily VI defined by only one member is shown by a small box along its branch. Ligands are indicated when applicable. The two boxed sequences correspond to cDNA clones of early metazoan NRs isolated in this study and corresponding to the PCR products of Fig. 1.