BACKGROUND: Prestin (SLC26A5) is responsible for acute sensitivity and frequency 
selectivity in the vertebrate auditory system. Limited knowledge of prestin is 
from experiments using site-directed mutagenesis or domain-swapping techniques 
after the amino acid residues were identified by comparing the sequence of 
prestin to those of its paralogs and orthologs. Frog prestin is the only 
representative in amphibian lineage and the studies of it were quite rare with 
only one species identified.
RESULTS: Here we report a new coding sequence of SLC26A5 for a frog species, 
Rana catesbeiana (the American bullfrog). In our study, the SLC26A5 gene of Rana 
has been mapped, sequenced and cloned successively using RNA-Seq. We measured 
the nonlinear capacitance (NLC) of prestin both in the hair cells of Rana's 
inner ear and HEK293T cells transfected with this new coding gene. HEK293T cells 
expressing Rana prestin showed electrophysiological features similar to that of 
hair cells from its inner ear. Comparative studies of zebrafish, chick, Rana and 
an ancient frog species showed that chick and zebrafish prestin lacked NLC. 
Ancient frog's prestin was functionally different from Rana.
CONCLUSIONS: We mapped and sequenced the SLC26A5 of the Rana catesbeiana from 
its inner ear cDNA using RNA-Seq. The Rana SLC26A5 cDNA was 2292 bp long, 
encoding a polypeptide of 763 amino acid residues, with 40% identity to mammals. 
This new coding gene could encode a functionally active protein conferring NLC 
to both frog HCs and the mammalian cell line. While comparing to its orthologs, 
the amphibian prestin has been evolutionarily changing its function and becomes 
more advanced than avian and teleost prestin.