3kxd
From Proteopedia
Crystal structure of the mthk rck in complex with cadmium
Structural highlights
FunctionMTHK_METTH Calcium-gated potassium channel. Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedRCK is a cytoplasmic regulatory domain of calcium-gated potassium channels. Binding of Ca(2+) by RCK leads to channel activation through a series of yet unknown conformational changes. Structures of the K(+) channel, MthK, and its cytoplasmic RCK domain revealed two binding sites for Ca(2+) per dimer. We determined the crystal structure of RCK in complex with Cd(2+) at 2.2A resolution. Cd(2+) activates MthK more efficiently, and binds at the same binding sites for Ca(2+) but with reduced coordination number. Two additional binding sites for Cd(2+) are found per dimer; one on the main Rossman-fold lobe, and the other on the small lobe of RCK. Using patch-clamp experiments, we demonstrate that Cd(2+) binding to these novel sites enhances activation by Cd(2+) and not by Ca(2+). The structure reveals a large negatively charged surface patch in the proximity of the Ca(2+)/Cd(2+) binding sites, charge neutralization of which appears to promote the channel open state. Structure of the MthK RCK in complex with cadmium.,Dvir H, Valera E, Choe S J Struct Biol. 2010 Aug;171(2):231-7. Epub 2010 Apr 4. PMID:20371380[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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