Potassium Channel Subunits: The MiRP Family

MiRP1 associates with HERG to generate I_Kr. The human gene for the α-subunit HERG can be expressed (here in Xenopus laevis oocytes in whole-cell mode) to generate functional VGK channels. Co-expression of MiRP1 is required, however, to generate a current that is typical of I_Kr in cardiac myocytes. Note that MiRP1 greatly decreases HERG-mediated currents and accelerates channel deactivation. Cells were held at -80 mV and depolarized for 3 s to voltages of -60 (red), -40 (green), -20 (yellow), 0 (purple), 20 (orange), and 40 (blue) mV, and were subsequently repolarized to –100 mV.