Rhodopsin is a photoreceptor protein found in retinal rods. It is a
complex formed by the binding of retinaldehyde, the oxidized form of retinol, to the protein opsin
and undergoes a series of complex reactions in response to visible light resulting in the
transmission of nerve impulses to the brain. Mutation of the rhodopsin gene is a major
contributor to various retinopathies such as retinitis pigmentosa. The disease-causing protein
generally aggregates with ubiquitin in inclusion bodies, disrupts the intermediate filament
network and impairs the ability of the cell to degrade non-functioning proteins which leads to
photoreceptor apoptosis (Berson et al., 1991). Other mutations on rhodopsin lead to X-linked
congenital stationary night blindness, mainly due to
constitutive activation, when the mutations
occur around the chromophore binding pocket of rhodopsin (Dryja et al.,1993). Several other
pathological states relating to rhodopsin have been discovered including poor post-Golgi
trafficking, dysregulative activation, rod outer segment instability and arrestin binding.
