1BL8

POTASSIUM CHANNEL (KCSA) FROM STREPTOMYCES LIVIDANS

Summary for 1BL8

• Entry DOI: 10.2210/pdb1bl8/pdb
• Descriptor: PROTEIN (POTASSIUM CHANNEL PROTEIN), POTASSIUM ION (3 entities in total)
• Functional Keywords: potassium channel, integral membrane protein, membrane protein
• Biological source: Streptomyces lividans
• Cellular location: Cell membrane; Multi-pass membrane protein: P0A334
• Total number of polymer chains: 4
• Total formula weight: 41129.13

Authors

Doyle, D.A.,Cabral, J.M.,Pfuetzner, R.A.,Kuo, A.,Gulbis, J.M.,Cohen, S.L.,Chait, B.T.,Mackinnon, R. (deposition date: 1998-07-23, release date: 1998-07-29, Last modification date: 2024-02-07)

Primary citation

Doyle, D.A.,Morais Cabral, J.,Pfuetzner, R.A.,Kuo, A.,Gulbis, J.M.,Cohen, S.L.,Chait, B.T.,MacKinnon, R.
The structure of the potassium channel: molecular basis of K+ conduction and selectivity.
Science, 280:69-77, 1998

PubMed Abstract: The potassium channel from Streptomyces lividans is an integral membrane protein with sequence similarity to all known K+ channels, particularly in the pore region. X-ray analysis with data to 3.2 angstroms reveals that four identical subunits create an inverted teepee, or cone, cradling the selectivity filter of the pore in its outer end. The narrow selectivity filter is only 12 angstroms long, whereas the remainder of the pore is wider and lined with hydrophobic amino acids. A large water-filled cavity and helix dipoles are positioned so as to overcome electrostatic destabilization of an ion in the pore at the center of the bilayer. Main chain carbonyl oxygen atoms from the K+ channel signature sequence line the selectivity filter, which is held open by structural constraints to coordinate K+ ions but not smaller Na+ ions. The selectivity filter contains two K+ ions about 7.5 angstroms apart. This configuration promotes ion conduction by exploiting electrostatic repulsive forces to overcome attractive forces between K+ ions and the selectivity filter. The architecture of the pore establishes the physical principles underlying selective K+ conduction.

PubMed: 9525859
DOI: 10.1126/science.280.5360.69

Experimental method

X-RAY DIFFRACTION (3.2 Å)