THE CLONING AND EXPRESSION OF A SODIUM-CHANNEL BETA-1-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 alpha-subunit, the major, pore-forming component. However, alpha-subunits are associated with one or more smaller beta-subunits, which have been implicated in the critical fine tuning of the gating properties of the channel. To investigate the properties of the beta-subunit, we have isolated a cDNA encoding the human brain beta1-subunit and assigned the corresponding gene to chromosome 19. We have also examined the effects of expressing the brain beta1-subunit on the kinetics of a coexpressed muscle sodium channel alpha-subunit. Our results underscore the functional importance of the beta1-subunit and imply a conserved mechanism for the interaction of the beta1-subunit with different alpha-subunits.