Title: Structure of the RCK domain from the E. coli K+ channel and demonstration of its presence in the human BK channel.

Authors: Y Jiang, A Pico, M Cadene, B T Chait, R MacKinnon

Journal, date & volume: Neuron, 2001 Mar , 29, 593-601

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11301020

Abstract
The intracellular C-terminal domain structure of a six-transmembrane K+ channel from Escherichia coli has been solved by X-ray crystallography at 2.4 A resolution. The structure is representative of a broad class of domains/proteins that regulate the conductance of K+ (here referred to as RCK domains) in prokaryotic K+ transporters and K+ channels. The RCK domain has a Rossmann-fold topology with unique positions, not commonly conserved among Rossmann-fold proteins, composing a well-conserved salt bridge and a hydrophobic dimer interface. Structure-based amino acid sequence alignments and mutational analysis are used to demonstrate that an RCK domain is also present and is an important component of the gating machinery in eukaryotic large-conductance Ca2+ activated K+ channels.