Biochemistry I   Spring & Fall Terms

Potassium Channel

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  Highlight Outer Pore
  K+ ion #1
  K+ ion #2
  K+ ion #3

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  Highlight Inner Pore
  Surface Residues
  (Chains A, B, & C)

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Potassium Channel from Streptomyces lividans, an Integral Membrane Protein
The initial view of the potassium channel* tetramer is from the extracellular side. Each subunit is colored separately and contains three a-helices. The inner and outer helices span the bilayer membrane. The K+ ions are shown spacefill, colored dark green (Fig. 3A).
  View perpendicular to the initial image (Fig. 3B).
  The aromatic residues at the membrane-facing interface are spacefill, colored yellow. The distance (Å) between membrane-spanning segments is shown. (Fig. 3C).
  "Inverted teepee" architecture of the tetramer. (Fig. 3D).
  Close-up of the mainchain atoms ( in residues 77 & 78) that complex the K+ ion #1.

For Problem Set #8, Fall Term 2001, the three "Highlight Outer Pore" buttons show a close-up view of each K+ ion. The protein is thin Ribbons, colored Chain; each highlighted K+ ion is Spacefill, colored green; nearby residues are Ball & Stick, colored CPK. All three K+ ions and a water molecule ("HOH1") are labeled.
The "Highlight Inner Pore" button displays the residues on the inner surface of three subunits as Spacefill. (Look at these residues "through Chain D".)
Schematic diagram of the K+ Channel in a pop-up window.
Part of a "Perspective" summary that accompanied the Science article by Doyle et al.

*The structure of the potassium channel from Streptomyces lividans (KcsA K+ channel) is described by Doyle et al. (1998) Science 280 69-77. The coordinate file is 1BL8.pdb. (References to Figs. above are to those of Doyle et al.)

Four more membrane protein structures:
 Bacteriorhodopsin       K+-Channel       Maltoporin       a-Hemolysin       Reaction Center

Back to the Protein Structure List.

smBack Return to Home Page Fall 2004 -or- Home Page Spring 2004.

8.21.04