This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.061812v1 89/3/1833    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Niu, S.-L. Articles by Mitchell, D. C. Search for Related Content PubMed PubMed Citation Articles by Niu, S.-L. Articles by Mitchell, D. C.

Effect of Packing Density on Rhodopsin Stability and Function in Polyunsaturated Membranes

Section of Fluorescence Studies, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland

Correspondence: Address reprint requests to Shui-Lin Niu, PhD, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rm. 3N-07, Bethesda, MD 20892-9410. Tel.: 301-435-6728; Fax: 301-594-0035; E-mail: sniu{at}niaaa.nih.gov.

Rod outer segment disk membranes are densely packed with rhodopsin. The recent notion of raft or microdomain structures in disk membranes suggests that the local density of rhodopsin in disk membranes could be much higher than the average density corresponding to the lipid/protein ratio. Little is known about the effect of high packing density of rhodopsin on the structure and function of rhodopsin and lipid membranes. Here we examined the role of rhodopsin packing density on membrane dynamic properties, membrane acyl chain packing, and the structural stability and function of rhodopsin using a combination of biophysical and biochemical techniques. We reconstituted rhodopsin into large unilamellar vesicles consisting of polyunsaturated 18:0,22:6n3PC, which approximates the polyunsaturated nature of phospholipids in disk membranes, with rhodopsin/lipid ratios ranging from 1:422 to 1:40. Our results showed that increased rhodopsin packing density led to reduced membrane dynamics revealed by the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene, increased phospholipid acyl chain packing, and reduced rhodopsin activation, yet it had minimal impact on the structural stability of rhodopsin. These observations imply that densely packed rhodopsin may impede the diffusion and conformational changes of rhodopsin, which could reduce the speed of visual transduction.

This article has been cited by other articles:

				M. P. Bennett and D. C. Mitchell Regulation of Membrane Proteins by Dietary Lipids: Effects of Cholesterol and Docosahexaenoic Acid Acyl Chain-Containing Phospholipids on Rhodopsin Stability and Function Biophys. J., August 1, 2008; 95(3): 1206 - 1216. [Abstract] [Full Text] [PDF]

				K. Boesze-Battaglia, M. Damek-Poprawa, D. C. Mitchell, L. Greeley, R. S. Brush, R. E. Anderson, M. J. Richards, and S. J. Fliesler Alteration of retinal rod outer segment membrane fluidity in a rat model of Smith-Lemli-Opitz syndrome J. Lipid Res., July 1, 2008; 49(7): 1488 - 1499. [Abstract] [Full Text] [PDF]

				A. V. Botelho, T. Huber, T. P. Sakmar, and M. F. Brown Curvature and Hydrophobic Forces Drive Oligomerization and Modulate Activity of Rhodopsin in Membranes Biophys. J., December 15, 2006; 91(12): 4464 - 4477. [Abstract] [Full Text] [PDF]