Figure 1

Tetrameric organization and membrane topology of HERG1 channel. a: Orthogonal view from the extracellular side demonstrating the tetrameric organization of HERG1 channel. b: Longitudinal view through the channel, taken from the longitudinal section shown at the top, displaying the membrane topology of only two reciprocal components across the pore of the tetrameric HERG1 channel. The channel exhibits a tetrameric composition of one main alpha-subunit (HERG1 protein, shown as α and in plain gray) and one auxiliary beta-subunit (minK or MiRP1 protein, shown as β and in dotted gray). The alpha-subunit is composed of six transmembrane-spanning domains (labelled S1-S6), S1-S4 being the voltage-sensing domain and S5-S6 the pore-forming domain. The beta-subunit comprises one transmembrane-spanning domain. The NH₂ and COOH termini are also shown. α, alpha-subunit; β, beta-subunit; P, pore.