Fig. 5.

Molecular phylogenetic analysis of PDE6 catalytic units. Phylogenetic tree for PDE6 catalytic sequences shows four distinct vertebrate clades, PDE6A, PDE6B, PDE6C, and a new group denoted PDE6X that was detected only in agnathan species. The tree was rooted using human PDE5A (NP_001074) and PDE11A (NP_058649); not shown. Analysis details (see Materials and Methods for explanation): Maximum likelihood; 1000 replicates; 35 sequences; partial deletion 90%, leaving 824 residues; JTT model; nearest neighbor interchange, with branch swap filter set to moderate. The vertical bar within the B group indicates the sequences for cartilaginous fish (see text). supplementary fig. S7, Supplementary Material online, shows the tree recalculated after omitting these three sequences.