The HOOK region of β subunits controls gating of voltage-gated Ca 2+ channels by electrostatically interacting with plasma membrane.

Recently, we showed that the HOOK region of the β2 subunit electrostatically interacts with the plasma membrane and regulates the current inactivation and phosphatidylinositol 4,5-bisphosphate (PIP ₂ ) sensitivity of voltage-gated Ca ²⁺ (Ca _V ) 2.2 channels. Here, we report that voltage-dependent gating and current density of the Ca _V 2.2 channels are also regulated by the HOOK region of the β2 subunit. The HOOK region can be divided into 3 domains: S (polyserine), A (polyacidic), and B (polybasic). We found that the A domain shifted the voltage-dependent inactivation and activation of Ca _V 2.2 channels to more hyperpolarized and depolarized voltages, respectively, whereas the B domain evoked these responses in the opposite directions. In addition, the A domain decreased the current density of the Ca _V 2.2 channels, while the B domain increased it. Together, our data demonstrate that the flexible HOOK region of the β2 subunit plays an important role in determining the overall Ca _V channel gating properties.