Alligator rhodopsin: sequence and biochemical properties.

We sequenced selected peptides of alligator rhodopsin that accounted for about half of the total protein. These sequences were confirmed when the total primary structure of alligator rhodopsin was deduced from the cDNA sequence. Differences in the amino-terminal region, compared to that of bovine rhodopsin, account for failure of cross-reactivity of several anti-bovine rhodopsin monoclonal antibodies. Differences in the carboxyl-terminal region give rise to limited antibody cross-reactivity and may also account for a slightly reduced ability of alligator rhodopsin to be phosphorylated by bovine rhodopsin kinase. Alligator rhodopsin regenerates much faster than bovine rhodopsin. The pseudo-first-order rate constant for alligator rhodopsin regeneration is approximately 25 times that of bovine. Phylogenetic analysis of 17 rhodopsin sequences indicates that the alligator is more closely related to the chicken than to the other species examined.