Potassium Channel Subunits: The MiRP Family

MinK associates with KCNQ1 to generate I_Ks. The human gene for the α-subunit KCNQ1 can be expressed (here in Xenopus laevis oocytes in whole-cell mode) to generate functional VGK channels (left). Co-expression of MinK is required, however, to generate a current that is like I_Ks in cardiac myocytes (right). Note that MinK greatly augments KCNQ1-mediated currents, and retards current activation. Cells were held at -80 mV and depolarized for 5 s to voltages of -60 (red), -40 (green), -20 (yellow), 0 (purple), 20 (orange), 40 (blue), and 60 (pink) mV.