Module 3: Figure K+ channel structure
The structural organization of Ca2+-sensitive K+ channels.
This figure illustrates the molecular organization of two apposing subunits (shown in blue and green). Of key importance is transmembrane (TM) domain 6, which is organized in the form of an inverted tepee. At the top, it forms a cradle that supports the pore-forming loop (P), whose helix is orientated with the negative (carbonyl) end of its dipole (shaded in red) facing inwards towards the pore. At the other end (facing the cytoplasm), the TM6 domains of the different subunits converge on each other to form the gated pore. The three-dimensional organization is best appreciated by looking at stereo views of the channel (Module 3: Figure K+ channel stereo views). An important part of this gate region is a kink in TM6, where it connects to the regulator of K+ conductance domain.