Coexpression and characterization of the human large-conductance Ca2+-activated K+ channel α + β1 subunits in HEK293 cells

Large-conductance Ca2+-activated K+ channel is formed by a tetramer of the pore-forming α-subunit and distinct accessory β-subunits (β1–β4) which contribute to BKCa channel molecular diversity. Accumulative evidences indicate that not only α-subunit alone but also the α + β subunit complex and/or β-subunit might play an important role in modulating various physiological functions in most mammalian cells. To evaluate the detailed pharmacological and biophysical properties of α + β1 subunit complex or β1-subunit in BKCa channel, we established an expression system that reliably coexpress hSloα + β1 subunit complex in HEK293 cells. The coexpression of hSloα + β1 subunit complex was evaluated by western blotting and immunolocalization, and then the single-channel kinetics and pharmacological properties of expressed hSloα + β1 subunit complex were investigated by cell-attached and outside-out patches, respectively. The results in this study showed that the expressed hSloα + β1 subunit complex demonstrated to be fully functional for its typical single-channel traces, Ca2+-sensitivity, voltage-dependency, high conductance (151 ± 7 pS), and its pharmacological activation and inhibition.