Deciphering the structural framework of glycine receptor anchoring by gephyrin.
Glycine is the major inhibitory neurotransmitter in the spinal cord and brain stem. Gephyrin is required to achieve a high concentration of glycine receptors (GlyRs) in the postsynaptic membrane, which is crucial for efficient glycinergic signal transduction. The interaction between gephyrin and the GlyR involves the E-domain of gephyrin and a cytoplasmic loop located between transmembrane segments three and four of the GlyR beta subunit. Here, we present crystal structures of the gephyrin E-domain with and without the GlyR beta-loop at 2.4 and 2.7 A resolutions, respectively. The GlyR beta-loop is bound in a symmetric 'key and lock' fashion to each E-domain monomer in a pocket adjacent to the dimer interface. Structure-guided mutagenesis followed by in vitro binding and in vivo colocalization assays demonstrate that a hydrophobic interaction formed by Phe 330 of gephyrin and Phe 398 and Ile 400 of the GlyR beta-loop is crucial for binding.
Kim
Eun Young
EY
Department of Biochemistry, Center for Structural Biology, State University of New York, Stony Brook, NY 11794-5115, USA.
Schrader
Nils
N
Smolinsky
Birthe
B
Bedet
Cécile
C
Vannier
Christian
C
Schwarz
Günter
G
Schindelin
Hermann
H
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018009:Receptors, Glycine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013569:Synapses
D002352:Carrier Proteins; D008565:Membrane Proteins; D018009:Receptors, Glycine; D011994:Recombinant Proteins; C073441:gephyrin