Biomaterial Database

Rhodopsin-cholesterol interactions in bovine rod outer segment disk membranes. 1996

A D Albert, and J E Young, and P L Yeagle

Department of Biochemistry, University at Buffalo School of Medicine and Biomedical Sciences, NY 14214, USA.

Cholesterol modulates the function of rhodopsin in the retinal rod outer segment (ROS) disk membranes. One mechanism for such modulation is cholesterol modulation of the properties of the membrane bilayer. This has been explored previously. Another possible mechanism is an interaction between the sterol and the protein, which has not been previously explored. In this study, the fluorescent sterol, cholestatrienol, was used to probe interactions between cholesterol and rhodopsin in bovine ROS disk membranes. Cholestatrienol was incorporated into the disk membranes by exchange from donor phospholipid vesicles. Fluorescence energy transfer from protein tryptophans to cholestatrienol was observed indicating close approach of this fluorescent sterol to the tryptophan. The effectiveness of the energy transfer was measured by the quenching of tryptophan fluorescence by cholestatrienol. The quenching of tryptophan fluorescence was directly related to the cholestatrienol content of the membranes. Cholesterol was incorporated into the disk membranes by exchange from donor phospholipid vesicles. The effect of increasing membrane cholesterol on the ability of cholestatrienol to quench rhodopsin tryptophan fluorescence was determined. This quenching was inversely proportional to the membrane cholesterol content. Furthermore the observed quenching was greater than could be explained by a simple dilution of the cholestatrienol by the addition of cholesterol to the membrane. These data suggest an interaction between the sterol and the protein. The specificity of this interaction was explored by the addition of ergosterol, instead of cholesterol, to the disk membranes. Ergosterol was not able to inhibit the quenching of protein trytophans beyond that due to dilution of the cholestatrienol by addition of ergosterol to the membrane. The ability of cholesterol to compete with cholestatrienol for that interaction suggests a 'site' at which cholesterol contacts rhodopsin. The inability of ergosterol to compete with cholestatrienol for this 'site' suggested that the site was specific for the structure of cholesterol.

UI	MeSH Term	Description	Entries
D007425	Intracellular Membranes	Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.	Membranes, Intracellular,Intracellular Membrane,Membrane, Intracellular
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002474	Cell-Free System	A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)	Cellfree System,Cell Free System,Cell-Free Systems,Cellfree Systems,System, Cell-Free,System, Cellfree,Systems, Cell-Free,Systems, Cellfree
D002782	Cholestenes	Steroids with methyl groups at C-10 and C-13 and a branched 8-carbon chain at C-17. Members include compounds with any degree of unsaturation; however, CHOLESTADIENES is available for derivatives containing two double bonds.
D002784	Cholesterol	The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.	Epicholesterol
D004735	Energy Transfer	The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER.	Transfer, Energy
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012243	Rhodopsin	A purplish-red, light-sensitive pigment found in RETINAL ROD CELLS of most vertebrates. It is a complex consisting of a molecule of ROD OPSIN and a molecule of 11-cis retinal (RETINALDEHYDE). Rhodopsin exhibits peak absorption wavelength at about 500 nm.	Visual Purple
D012374	Rod Cell Outer Segment	The portion of a retinal rod cell situated between the ROD INNER SEGMENT and the RETINAL PIGMENT EPITHELIUM. It contains a stack of photosensitive disk membranes laden with RHODOPSIN.	Rod Outer Segment,Rod Outer Segments,Outer Segment, Rod,Outer Segments, Rod
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence