The 2-fold axis of the dimer is directed perpendicularly to the paper through the center of each figure. In the vicinity of site 1, a new interprotomer interaction is found between the LB2 domains. Notably, these three residues cannot reach glutamate in the open conformation because of the large spacing between the two domains. Lide D R, editor. Therefore, these direct contacts are not sufficient to discriminate the group III receptors from the others. ireb-4r

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The ureb-4r wedges the protomer to maintain an inactive open form. These findings provide a structural basis to describe the link between ligand binding and the dimer interface.

Nakanishi S, Masu M. Refinement by use of cns 16 provided the converged structure with an R cryst value of 0.


The coloring is the same as in Fig. We are grateful to Dr. Therefore, these direct contacts are not sufficient to discriminate the group III receptors from the others.


Hollmann M, Heinemann S. On agonist binding to mGluR, the population of the open—open dimer decreases, because the agonist induces domain closure. We have recently reported the crystal structures of the extracellular ligand-binding region of the homodimeric mGluR subtype 1 m1-LBR in the complex with glutamate and in the two unliganded forms 4.

The atomic coordinates have been deposited in the Protein Data Bank, www. The structural comparison between the active and resting dimers suggests that glutamate binding tends to induce domain closing and a small shift of jreb-4r helix ireb-4g the dimer interface. Larger open angles caused steric collisions between the two regions, ranging through residues — and —, respectively. Miyashita T, Kubo Y. The electrostatic interactions dielectric constant 4.

The interactions formed by these conserved residues should be common in the mGluRs. This structural feature of the open protomer wedged by this ligand may provide hints for the design of new antagonists. National Center for Biotechnology InformationU.


On the other hand, the interprotomer van der Waals energy is relatively constant. Interprotomer interactions at the LB2 interface ireb4-r differ between the closed—closed Fig. The LB1 interface is approximately parallel to Aand its orthogonal view is on B. Yellow and green represent the closed and open protomers, respectively.

C An equilibrium model proposed for m1-LBR.

Computer Simulations of Biological Systems. The potential energies of the electrostatic Fig. The data were processed with mosflm 13 and were reduced with scala in CCP4 14 with an R merge of 0. Therefore, it appears reasonable that prolonged receptor activation, but not its ignition, explains the physiological role of the metal ion According to the conformational notation of the LB1 interface, which determines the R and A conformations 4this dimer is defined as the A state.

Because the crystal was too sensitive to find adequate conditions for cryoprotection, the diffraction data had to be collected at K. Consequently, radiation damage was so serious that only partial data could be obtained with one crystal. In fact, the receptor is activated by glutamate without extracellular metal cation.


This figure was generated as if the front protomer saturated color in B were viewed from the left. Irreb-4r and green boxes represent residues forming direct and water-mediated interactions, respectively, with the corresponding ligand.

Ireb-4r Zombi

D is replaced with Glu in the other subtypes. Lide D R, editor.

Sunter Tocris Cookson, Ltd. This recognition scheme implies that the role of the antagonist is to wedge the open protomer conformation.


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