Coexpression of the cardiac beta subunit with the alpha1 subunit significantly increased the number of channel openings in all four conductance levels without changing the conductance values.
The cloned cardiac L-type Ca2+ channel alpha1 subunit alone can produce four distinct subconductance levels, while the beta subunit increases the frequency of these openings.
Formation of single channel subconductance is one of the unique characteristics of the L-type Ca2+ channel. Although alpha1 subunit exhibits a primary function of the channel, it remains uncertain whether alpha1 subunit alone is able to produce subconductance. We tested this by studying single channel currents of cloned cardiac alpha1 subunit expressed in Chinese hamster fibroblast cells, with/without coexpression of cardiac beta subunit. The alpha1 subunit exhibited four distinct levels of conductance (22.7, 14.3, 6.2 and 3.2 pS). Coexpression of beta subunit significantly increased the number of openings in all four levels of conductance without changing the conductance values.
Gondo et al. (Fri,) reported a other. Coexpression of cardiac beta subunit vs. alpha1 subunit alone was evaluated on Single channel subconductance levels and number of openings. Coexpression of the cardiac beta subunit with the alpha1 subunit significantly increased the number of channel openings in all four conductance levels without changing the conductance values.