| Autor: |
Upton BA; Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.; Center for Chronobiology, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.; Molecular & Developmental Biology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio.; Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio., Díaz NM; Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington., Gordon SA; Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington., Van Gelder RN; Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington.; Departments of Biological Structure and Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, Washington., Buhr ED; Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington., Lang RA; Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.; Center for Chronobiology, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.; Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.; Department of Ophthalmology, University of Cincinnati College of Medicine, Cincinnati, Ohio. |
| Abstrakt: |
Animals have evolved light-sensitive G protein-coupled receptors, known as opsins, to detect coherent and ambient light for visual and nonvisual functions. These opsins have evolved to satisfy the particular lighting niches of the organisms that express them. While many unique patterns of evolution have been identified in mammals for rod and cone opsins, far less is known about the atypical mammalian opsins. Using genomic data from over 400 mammalian species from 22 orders, unique patterns of evolution for each mammalian opsins were identified, including photoisomerases, RGR-opsin (RGR) and peropsin (RRH), as well as atypical opsins, encephalopsin (OPN3), melanopsin (OPN4), and neuropsin (OPN5). The results demonstrate that OPN5 and rhodopsin show extreme conservation across all mammalian lineages. The cone opsins, SWS1 and LWS, and the nonvisual opsins, OPN3 and RRH, demonstrate a moderate degree of sequence conservation relative to other opsins, with some instances of lineage-specific gene loss. Finally, the photoisomerase, RGR, and the best-studied atypical opsin, OPN4, have high sequence diversity within mammals. These conservation patterns are maintained in human populations. Importantly, all mammalian opsins retain key amino acid residues important for conjugation to retinal-based chromophores, permitting light sensitivity. These patterns of evolution are discussed along with known functions of each atypical opsin, such as in circadian or metabolic physiology, to provide insight into the observed patterns of evolutionary constraint. |
