IONIC CHANNEL ACTIVITY-INDUCED BY FUSION OF RHODOSPIRILLUM-RUBRUM CHROMATOPHORES WITH A PLANAR BILAYER-LIPID MEMBRANE

The present work concerns mechanisms of ionic conductivity of photosyn thetic membranes. It is shown that reconstitution of vesicles of photo synthetic membranes (chromatophores) of purple bacteria Rhodospirillum rubrum into a planar bilayer lipid membrane leads to fluctuations of current showing the existence of a channel with a predominant conducta nce of similar to 230 pS in the presence of 100 mM KCl. Measurements u nder the conditions of KCl gradient prove that this channel is cation selective (R(K)/R(Cl) = 7.2). Voltage inactivation of the channel is d emonstrated which is prevented by treatment with trypsin.