[Molecular mechanisms of photoreception. V. Reconstitution of a sodium channel on an artificial lipid membrane modified by bovine rod outer segment components].
An attempt is made to reconstitute the Na+-conductivity elements of rod outer segment (ROS) plasma membrane on the artificial lipid membrane (ALM). ALM were modified by preparation with bovine ROS plasma membrane fragments. Discrete fluctuations of the ALM conductivity were observed at addition of this preparation to the ALM bathing solutions to a final concentration of 0.1--1.0 microgram/ml. The magnitude of these fluctuations was about 25 pS at 140 mM NaCl. The modified ALM possessed preferentially the Na+-conductivity, which was at least five times as great as that for K+ or Li+. The modified ALM showed practically no conductivity for Cl-. The Na+-channels were voltage-dependent. The Na+-channels were "sensitive to visible light" at some experimental conditions. The optimal conditions were obtained for reconstitution of Na+-channel on the ALM. The temporal and termal stabilities of the modified preparation were investigated. It was shown that the frequency of the modified ALM conductivity fluctuations are dependent on temperature and on lipids composition of ALM. The data obtained in our work are in a good agreement with the results of electrophysiological studies of photoreceptor cells. It may be indicated, that the investigated ALM contains the Na+-channel of the ROS plasma membranes. It is suggested that the reconstituted system will be useful for studying the principles of regulation of ROS plasma membrane sodium conductivity and the nature of a mediator in a photoreceptor transduction mechanism.
D000818:Animals; D002414:Cations, Monovalent; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes; D010786:Photoreceptor Cells / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D002414:Cations, Monovalent; D002712:Chlorides; D007473:Ion Channels; D008081:Liposomes; D012964:Sodium
Molikuliarnye mekhanizmy fotoretseptsii. V. Popytka modelirovaniia tsitoplazmaticheskoĭ membrany fotoretseptora na iskusstvennoĭ lipidnoĭ membrane, modifitsirovannoĭ komponentami naruzhnykh segmentov palochek setchatki byka.