Abstract
Gephyrin is a bi-functional modular protein involved in molybdenum cofactor biosynthesis and in postsynaptic clustering of inhibitory glycine receptors (GlyRs). Here, we show that full-length gephyrin is a trimer and that its proteolysis in vitro causes the spontaneous dimerization of its C-terminal region (gephyrin-E), which binds a GlyR beta-subunit-derived peptide with high and low affinity. The crystal structure of the tetra-domain gephyrin-E in complex with the beta-peptide bound to domain IV indicates how membrane-embedded GlyRs may interact with subsynaptic gephyrin. In vitro, trimeric full-length gephyrin forms a network upon lowering the pH, and this process can be reversed to produce stable full-length dimeric gephyrin. Our data suggest a mechanism by which induced conformational transitions of trimeric gephyrin may generate a reversible postsynaptic scaffold for GlyR recruitment, which allows for dynamic receptor movement in and out of postsynaptic GlyR clusters, and thus for synaptic plasticity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Binding Sites
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Carrier Proteins / chemistry
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Carrier Proteins / drug effects
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Carrier Proteins / isolation & purification
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Carrier Proteins / metabolism*
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Carrier Proteins / ultrastructure
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Chromatography, Gel
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Coenzymes / metabolism
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Crystallography, X-Ray
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Dimerization
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Hydrogen-Ion Concentration
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Hydrolysis
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Mass Spectrometry
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Membrane Proteins / chemistry
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Membrane Proteins / drug effects
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Membrane Proteins / isolation & purification
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Membrane Proteins / metabolism*
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Membrane Proteins / ultrastructure
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Metalloproteins / metabolism
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Models, Chemical
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Models, Molecular
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Molybdenum Cofactors
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Peptide Fragments / chemistry
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Peptide Fragments / genetics
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Protein Binding
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Protein Conformation
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Protein Structure, Tertiary
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Protein Subunits / metabolism
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Pteridines / metabolism
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Rats
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Receptors, Glycine / chemistry
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Receptors, Glycine / genetics
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Receptors, Glycine / metabolism*
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Solutions
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Sulfates / chemistry
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Surface Plasmon Resonance
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Synapses / metabolism
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Trypsin / pharmacology
Substances
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Carrier Proteins
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Coenzymes
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Membrane Proteins
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Metalloproteins
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Molybdenum Cofactors
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Peptide Fragments
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Protein Subunits
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Pteridines
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Receptors, Glycine
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Solutions
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Sulfates
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gephyrin
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molybdenum cofactor
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Trypsin