Keeping an Eye on Vision: Molecular Genetics and Evolution of Visual Pigment Proteins

Benedict Darren, Belinda Chang

Abstract


Vision is intimately related to the ability and means with which an organism interacts with its environment. On a molecular level, the absorption of photons by visual pigment complexes in the retina, known as opsins, initiates a downstream cascade which culminates in the sensory impulse signaling the perception of light. Resolution of the rhodopsin crystal structure and subsequent biochemical assays have revealed key residues essential to the basic function of these light-sensitive proteins. In recent years, a body of research has surmounted to fully catalog the range of spectral sensitivities observed in opsins across a variety of vertebrate taxa. This review addresses the fundamental molecular mechanisms of spectral tuning which have been uncovered by sequence analyses and mutagenesis studies. Moreover, the upstream forces which drive these shifts in sensitivity are considered, particularly spectral heterogeneity across space, and developmental changes across time. These insights into the molecular genetics and evolution of visual pigments constitute an improved understanding of a protein’s capacity to develop novel and specialized functions.

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© University of Toronto Journal of Undergraduate Life Sciences.