Cloning of the rhodopsin-encoding gene from the rod-less lizard Anolis carolinensis.

The rhodopsin (Rh) of the lizard Anolis carolinensis has only been detected in the pineal gland which controls circadian rhythms [Foster et al., J. Comp. Physiol. (1993) 33-45]. In the present study, we isolated and sequenced a genomic DNA clone for the A. carolinensis Rh gene. The deduced amino acid (aa) sequence revealed six A. carolinensis-specific replacements in conserved aa residues among vertebrate Rhs. Four out of these six replacements (S22N, N199H, E232A and T319M) reside outside the transmembrane (TM) domains. Some of these replacements might have been required for Rh to function solely in the pineal gland.