1K4D

Potassium Channel KcsA-Fab complex in low concentration of K+

Summary for 1K4D

• Entry DOI: 10.2210/pdb1k4d/pdb
• Descriptor: antibody Fab fragment heavy chain, antibody Fab fragment light chain, potassium channel KcsA, ... (8 entities in total)
• Functional Keywords: 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: 60929.02

Authors

Zhou, Y.,Morais-Cabral, J.H.,Kaufman, A.,MacKinnon, R. (deposition date: 2001-10-07, release date: 2001-11-14, Last modification date: 2024-11-13)

Primary citation

Zhou, Y.,Morais-Cabral, J.H.,Kaufman, A.,MacKinnon, R.
Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.
Nature, 414:43-48, 2001

PubMed Abstract: Ion transport proteins must remove an ion's hydration shell to coordinate the ion selectively on the basis of its size and charge. To discover how the K+ channel solves this fundamental aspect of ion conduction, we solved the structure of the KcsA K+ channel in complex with a monoclonal Fab antibody fragment at 2.0 A resolution. Here we show how the K+ channel displaces water molecules around an ion at its extracellular entryway, and how it holds a K+ ion in a square antiprism of water molecules in a cavity near its intracellular entryway. Carbonyl oxygen atoms within the selectivity filter form a very similar square antiprism around each K+ binding site, as if to mimic the waters of hydration. The selectivity filter changes its ion coordination structure in low K+ solutions. This structural change is crucial to the operation of the selectivity filter in the cellular context, where the K+ ion concentration near the selectivity filter varies in response to channel gating.

PubMed: 11689936
DOI: 10.1038/35102009

Experimental method

X-RAY DIFFRACTION (2.3 Å)