Amino acid sequence conservation in the reptilian and avian OR gene repertoires. Sequence logos of intact (A) green anole, (B) chicken and (C) zebra finch OR sequences. The logos were generated from an alignment of 110, 214, and 134 predicted full-length OR sequences from the green anole, chicken and zebra finch using the program WebLogo. Heights of amino acid letters represent the relative frequency at a given position. The overall height at a given position indicates the level of sequence conservation. Bars below amino acids indicate transmembrane regions (TM). Note that the exact number and precise placement of the TMs has not been experimentally verified and should thus be treated with caution. The position of intracellular (IC) and extracellular (EC) domains are also indicated. Black boxes indicate four conserved motifs that are characteristic for vertebrate ORs.