Functional heterogeneity of gephyrins.
Postsynaptic clustering of the glycine receptor requires the cytoplasmic protein gephyrin, which interacts with the receptor beta subunit. Several variants of gephyrin are generated by alternative splicing and differ by the presence of short amino acid sequences (cassettes) in the N-terminal half of the molecule. In this work, seven isoforms of gephyrin were cloned from adult rat spinal cord, some of then containing new cassettes. The relationships between gephyrin structure and recognition of glycine receptor beta subunit were analyzed. This was carried out by GST-pulldown assays using the beta subunit cytoplasmic loop and cotransfection experiments of GFP-tagged gephyrins with an alpha1 subunit bearing the gephyrin-binding site of the beta subunit. Data demonstrated that not all gephyrin molecules can bind to the beta subunit. Identified cassettes modulate this interaction. It is thus concluded that the function of gephyrin in synapse formation can rely on a structure acquired through cassette combinations.
Meier
J
J
Laboratoire de Biologie Cellulaire de la Synapse Normale et Pathologique, I.N.S.E.R.M. U497, Ecole Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France.
De Chaldée
M
M
Triller
A
A
Vannier
C
C
D017398:Alternative Splicing / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000502:physiology; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D017930:Genes, Reporter; D018740:Genetic Heterogeneity; D049452:Green Fluorescent Proteins; D007202:Indicators and Reagents / Q000378:metabolism; D007536:Isomerism; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013116:Spinal Cord / Q000737:chemistry; D013329:Structure-Activity Relationship; D013569:Synapses / Q000737:chemistry / Q000378:metabolism*; D014162:Transfection
D002352:Carrier Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C073441:gephyrin; D049452:Green Fluorescent Proteins