Modification of the Na⁺ current conducted by the rat skeletal muscle α subunit by coexpression with a human brain β subunit

Sodium channels are multimeric structures composed of α and β subunits. Oocytes injected with RNA encoding only the α subunit express voltage-gated Na⁺ currents. The kinetics of inactivation, however, are abnormal. Co-injection of rat brain α and β subunits modifies inactivation of I_Na such that it closely resembles endogenous currents [1]. Here we show that a β subunit derived from human brain directs the same functional modification of I_Na expressed by a rat skeletal muscle α subunit. This implies that functional domains for the interaction of α and β subunits are highly conserved across both tissues and species.