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| {{STRUCTURE_1ii5| PDB=1ii5 | SCENE= }} | | {{STRUCTURE_1ii5| PDB=1ii5 | SCENE= }} |
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| '''CRYSTAL STRUCTURE OF THE GLUR0 LIGAND BINDING CORE COMPLEX WITH L-GLUTAMATE'''
| | ===CRYSTAL STRUCTURE OF THE GLUR0 LIGAND BINDING CORE COMPLEX WITH L-GLUTAMATE=== |
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| ==Overview==
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| High-resolution structures of the ligand binding core of GluR0, a glutamate receptor ion channel from Synechocystis PCC 6803, have been solved by X-ray diffraction. The GluR0 structures reveal homology with bacterial periplasmic binding proteins and the rat GluR2 AMPA subtype neurotransmitter receptor. The ligand binding site is formed by a cleft between two globular alpha/beta domains. L-Glutamate binds in an extended conformation, similar to that observed for glutamine binding protein (GlnBP). However, the L-glutamate gamma-carboxyl group interacts exclusively with Asn51 in domain 1, different from the interactions of ligand with domain 2 residues observed for GluR2 and GlnBP. To address how neutral amino acids activate GluR0 gating we solved the structure of the binding site complex with L-serine. This revealed solvent molecules acting as surrogate ligand atoms, such that the serine OH group makes solvent-mediated hydrogen bonds with Asn51. The structure of a ligand-free, closed-cleft conformation revealed an extensive hydrogen bond network mediated by solvent molecules. Equilibrium centrifugation analysis revealed dimerization of the GluR0 ligand binding core with a dissociation constant of 0.8 microM. In the crystal, a symmetrical dimer involving residues in domain 1 occurs along a crystallographic 2-fold axis and suggests that tetrameric glutamate receptor ion channels are assembled from dimers of dimers. We propose that ligand-induced conformational changes cause the ion channel to open as a result of an increase in domain 2 separation relative to the dimer interface.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11518533}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11518533 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11518533}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Olson, R.]] | | [[Category: Olson, R.]] |
| [[Category: Membrane protein]] | | [[Category: Membrane protein]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 20:01:49 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 12:14:52 2008'' |