BCHM 210 Midterm: Potassium Channel Structure
Document Summary
The bacterial k+ channel consist of 4 identical subunits each having two membrane spanning helices. The k1 channel, composed of four identical subunits, is cone shaped, with the larger opening facing the inside of the cell (center). A view down the pore, looking toward the outside of the cell, shows the relations of the individual subunits (left). One of the four identical subunits of the pore is illustrated at the right, with the pore-forming region shown in gray: 1. The channel on the inside of the cell is 10 in diameter: 2. The channel is filled with water so that hydrated k+ moves into the channel a distance of 22 : 3. The water filled region narrows to 8 at one point: 4. The channel then narrows to 3 and the k+ ion must shed its water molecules: 5. From this point on the k+ interacts with carbonyl groups of pore amino acids.
