Potassium Channel KcsA

Ion channels, such as potassium channels, are essential to the way our nerves work. This is a model of the potassium channel KcsA, from _Streptomyces lividans_. KcsA is a tetrameric protein composed of four identical subunits.

"Potassium channels are designed to allow the flow of potassium ions across the membrane, but to block the flow of other ions--in particular, sodium ions."
--http://www.rcsb.org/pdb/101/motm.do?momID=38

Four copies of 1K4C-surf_fixed.stl must be printed to make the