Sequences and Structures of Retinal Proteins

The past few years have been an exciting period in the field of the structure of retinal proteins, especially the visual pigments. A significant achievement is the 9 A projection map of bovine rhodopsin. This not only provides knowledge of the three-dimensional structure of visual pigments, but also establishes a more reliable basis for the structural modeling of all the G-protein-coupled receptors. The modeling of such three-dimensional structures will eventually lead to a better understanding of the function of visual pigments and other G-protein-coupled receptors. Our goal in this article is to draw attention to recent developments in the structure of retinal proteins, with special emphasis on visual pigments. By combining a wide range of existing experimental data with the results of theoretical calculations, a new three-dimensional structure of visual pigments, which differs from the models which have so far been reported, is proposed.