The cloning and expression of a sodium channel β1-subunit cDNA from human brain

Electrical excitability of neurons and muscle cells is mediated largely through the actions of the voltage-gated sodium channel. Initiation and propagation of the action potential is a direct result of the precisely controlled inward flux of sodium through these channels. Much attention has been paid to the sodium channel α-subunit, the major, pore-forming component. However, α-subunits are associated with one or more smaller β-subunits, which have been implicated in the critical fine tuning of the gating properties of the channel. To investigate the properties of the β-subunit, we have isolated a cDNA encoding the human brain β1-subunit and assigned the corresponding gene to chromosome 19. We have also examined the effects of expressing the brain β1-subunit on the kinetics of a coexpressed muscle sodium channel α-subunit. Our results underscore the functional importance of the β1-subunit and imply a conserved mechanism for the interaction of the β1-subunit with different α-subunits.