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Allison Whited, Jessalee Detweiler, Paul Park; Structural characterization of mouse and human rhodopsin in native membranes. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2481.
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© ARVO (1962-2015); The Authors (2016-present)
Rhodopsin is the light receptor located in the rod outer segments of photoreceptor cells in the retina. There are over 100 point mutations identified in rhodopsin that cause retinitis pigmentosa (RP). Characterization of the structure and function of rhodopsin is important to understanding the mechanism by which single amino acid changes cause human retinal disease. Much of the information available about rhodopsin and its role in disease has been obtained from non-human species including mice and cows. To understand human disease we must validate the use of these animal models and ensure that the structural properties of human rhodopsin are similar to rhodopsins from other species. In the current study, we compared the structural properties of human and murine rhodopsin using atomic force microscopy (AFM) and single molecule force spectroscopy (SMFS).
Rhodopsin embedded in native rod outer segment disc membranes was isolated from the retina of human and mouse eyes. Preparations of rhodopsin in native disc membranes were investigated by AFM and SMFS, which are nanotechnologies that offer insights into fundamental questions related to visual macromolecules. AFM was used to image rhodopsin within its native context of the rod outer segment disc membranes. SMFS was used to investigate the intramolecular interactions stabilizing the structure of rhodopsin.
AFM revealed that rhodopsin from both human and murine origin is densely packed in the membrane and organized into microdomains. No appreciable difference was observed in the organization of rhodopsin within human or murine rod outer segment disc membranes. SMFS studies were used to mechanically unfold single rhodopsin molecules. Force traces recorded the mechanical unfolding events of rhodopsin. SMFS on mouse rhodopsin revealed that the structure is organized into several regions exhibiting intrinsic stability. Preliminary force traces have also been collected for human rhodopsin and exhibit similar unfolding events as those observed in force traces of mouse rhodopsin.
We have applied AFM and SMFS to compare the quaternary organization and stabilizing intramolecular interactions of human and mouse rhodopsin. Preliminary studies indicate similarities in these structural properties between rhodopsin from human and murine origins.
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