FUNCTIONAL RECONSTITUTION OF ION CHANNELS FROM PARAMECIUM CORTEX INTOARTIFICIAL LIPOSOMES

Toward isolating channel proteins from Paramecium, we have explored th e possibility of functionally reconstituting ion channels in an artifi cial system. Proteins from Paramecium cortex reconstituted with soybea n azolectin retained several channels whose activities were readily re gistered under patch clamp. The most commonly encountered activities w ere three: (i) a 71-pS cation channel that opens at all voltages unles s di-or trivalent cations were added to close them, (ii) a 40 pS monov alent cation channel, and (iii) a large-conductance channel that prefe rs anions and exhibits many subconductance states. These channels surv ived mild detergent treatments without observable functional alteratio ns. The possible origin of these channels from internal membranes, the possible role of 71-pS channel in internal Ca2+ release, and the pros pects of their purification are discussed.