2NLJ

Potassium Channel KcsA(M96V)-Fab complex in KCl

Summary for 2NLJ

• Entry DOI: 10.2210/pdb2nlj/pdb
• Related: 2itc 2itd
• Descriptor: antibody Fab fragment light chain, antibody Fab fragment heavy chain, Voltage-gated potassium channel, ... (6 entities in total)
• Functional Keywords: voltage-gated channel, transmembrane, ionic channel, ion transport, k channel, protein-antibody fab complex, membrane protein
• Biological source: Streptomyces lividans; More
• Cellular location: Cell membrane; Multi-pass membrane protein: P0A334
• Total number of polymer chains: 3
• Total formula weight: 60768.81

Authors

Lockless, S.W.,Zhou, M.,MacKinnon, R. (deposition date: 2006-10-20, release date: 2007-05-15, Last modification date: 2024-10-16)

Primary citation

Lockless, S.W.,Zhou, M.,Mackinnon, R.
Structural and Thermodynamic Properties of Selective Ion Binding in a K(+) Channel.
Plos Biol., 5:e121-e121, 2007

PubMed Abstract: Thermodynamic measurements of ion binding to the Streptomyces lividans K(+) channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray crystallography. Here we use these assays to show that the ion radius dependence of selectivity stems from the channel's recognition of ion size (i.e., volume) rather than charge density. Ion size recognition is a function of the channel's ability to adopt a very specific conductive structure with larger ions (K(+), Rb(+), Cs(+), and Ba(2+)) bound and not with smaller ions (Na(+), Mg(2+), and Ca(2+)). The formation of the conductive structure involves selectivity filter atoms that are in direct contact with bound ions as well as protein atoms surrounding the selectivity filter up to a distance of 15 A from the ions. We conclude that ion selectivity in a K(+) channel is a property of size-matched ion binding sites created by the protein structure.

PubMed: 17472437
DOI: 10.1371/journal.pbio.0050121

Experimental method

X-RAY DIFFRACTION (2.52 Å)