| | |
Summary: Crystal structure and mechanism of a
calcium-gated potassium channel
Youxing Jiang, Alice Lee, Jiayun Chen, Martine Cadene, Brian T. Chait & Roderick MacKinnon
Howard Hughes Medical Institute, Laboratory of Molecular Neurobiology and Biophysics and Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller
University, 1230 York Avenue, New York, New York 10021, USA
...........................................................................................................................................................................................................................
Ion channels exhibit two essential biophysical properties; that is, selective ion conduction, and the ability to gate-open in response
to an appropriate stimulus. Two general categories of ion channel gating are defined by the initiating stimulus: ligand binding
(neurotransmitter- or second-messenger-gated channels) or membrane voltage (voltage-gated channels). Here we present
the structural basis of ligand gating in a K1
channel that opens in response to intracellular Ca21
. We have cloned, expressed,
analysed electrical properties, and determined the crystal structure of a K1
channel (MthK) from Methanobacterium thermo-
autotrophicum in the Ca21
-bound, opened state. Eight RCK domains (regulators of K1
conductance) form a gating ring at the
intracellular membrane surface. The gating ring uses the free energy of Ca21
binding in a simple manner to perform mechanical
work to open the pore.
|
