Abstract
We studied rhodopsin oligomerization as a function of rhodopsin concentration and lipid composition and related oligomerization to shifts in rhodopsin function. In the rod outer segment disks of the retina, rhodopsin is densely packed in phospholipid bilayers with a high content of polyunsaturated acyl chains. In model membranes, increasing rhodopsin packing density was linked to a shift in the metarhodopsin-I (MI)/metarhodopsin-II (MII) equilibrium towards MI as well as to lower rates of MII formation. We reconstituted rhodopsin into various phosphatidylcholine bilayers at rhodopsin/lipid ratios ranging from 1:1,000 to 1:70 and followed rhodopsin oligomerization by cross linking of rhodopsin and changes in lipid-rhodopsin interactions by 2H NMR. The amount of MII formed after photoactivation was determined by UV/vis spectroscopy and the rate of transducin activation studied with a GTPγS-assay. At low rhodopsin concentrations (1/300 and lower) rhodopsin appears to be predominantly monomeric. At rhodopsin/lipid ratios higher than 1/300, the level of oligomerization increases in a highly cooperative fashion with concentration such that at physiological concentrations rhodopsin is mostly oligomeric. Protein function correlated tightly with rhodopsin oligomerization. Data on the influence of bilayer properties on the monomer - oligomer transition of rhodopsin and the rate of transducin activation will be presented.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
