Summary

The β subunit is a cytoplasmic component that normal-izes the current amplitude, kinetics, and voltage depen-dence of voltage-gated Ca2+ channels. Here, we identify a 30 amino acid domain of the β subunit that is sufficient to induce a stimulation and shift in the voltage depen-dence of activation of the Ca2+ channel currents. This domain is located at the amino terminus of the second region of high conservation among all β subunit gene products. Single point mutations within this region on the β1b subunit modified or abolished the stimulation of Ca2+ channel currents and the binding of the β subunit to the α1A subunit. The binding of this domain is also required for the observed changes in kinetics and voltage dependence of steady-state inactivation induced by β subunits