PDBsum entry 1u12

Membrane protein

PDB id: 1u12

Contents

Protein chains

131 a.a.

Ligands

SO4 ×2

Metals

__K ×4

IOD ×31

Waters ×11

References listed in PDB file

Key reference

Title

Structural basis of ligand activation in a cyclic nucleotide regulated potassium channel.

Authors

G.M.Clayton, W.R.Silverman, L.Heginbotham, J.H.Morais-Cabral.

Ref.

Cell, 2004, 119, 615-627. [DOI no: 10.1016/j.cell.2004.10.030]

PubMed id

15550244

Abstract

Here we describe the initial functional characterization of a cyclic nucleotide regulated ion channel from the bacterium Mesorhizobium loti and present two structures of its cyclic nucleotide binding domain, with and without cAMP. The domains are organized as dimers with the interface formed by the linker regions that connect the nucleotide binding pocket to the pore domain. Together, structural and functional data suggest the domains form two dimers on the cytoplasmic face of the channel. We propose a model for gating in which ligand binding alters the structural relationship within a dimer, directly affecting the position of the adjacent transmembrane helices.

Figure 5.
Figure 5. Dimer Interface(A) Ribbon representation of the R348A mutant dimer, with ions bound in the ligand binding sites. Side chains of some residues on the interface are shown.(B) Stereoviews of the dimer interface from the wild-type (top) and mutant (bottom) domain structures. The αC of Gly221 is shown as a purple sphere. TM, transmembrane helix.

Figure 7.
Figure 7. Schematic of Gating ModelTwo of the four CNB domains are shown attached to the last transmembrane helices. The open and closed states correspond to liganded and unliganded structures, respectively. Arrows indicate the direction of movement to attain the structure shown, from the alternate conformation. The orientation of the domains relative to the transmembrane helices is arbitrary.

The above figures are reprinted by permission from Cell Press: Cell (2004, 119, 615-627) copyright 2004.