4 CONDUCTANCE LEVELS OF CLONED CARDIAC L-TYPE CA2+ CHANNEL ALPHA(1) AND ALPHA(1) BETA SUBUNITS/

Formation of single channel subconductance is one of the unique charac teristics of the L-type Ca2+ channel, Although alpha(1) subunit exhibi ts a primary function of the channel, it remains uncertain whether alp ha(1) subunit alone is able to produce subconductance, We tested this by studying single channel currents of cloned cardiac alpha(1) subunit expressed in Chinese hamster fibroblast cells, with/without coexpress ion of cardiac beta subunit, The alpha(1) subunit exhibited four disti nct levels of conductance (22.7, 14.3, 6.2 and 3.2 pS), Coexpression o f beta subunit significantly increased the number of openings in all f our levels of conductance without changing the conductance values. (C) 1998 Federation of European Biochemical Societies.