Disturbances of Ligand Potency and Enhanced Degradation of the Human Glycine Receptor at Affected Positions G160 and T162 Originally Identified in Patients Suffering from Hyperekplexia

摘要: Ligand-binding of Cys-loop receptors is determined by N-terminal extracellular loop structures from the plus as well minus side two adjacent subunits in pentameric receptor complex. An aromatic residue B glycine (GlyR) undergoes direct interaction with incoming ligand via cation-π interactions. Recently we showed that mutated residues identified human patients suffering hyperekplexia disturb ligand-binding. Here, exchanged affected amino acids found related members family to determine effects chain volume for ion channel properties. GlyR variants were characterized vitro following transfection into cell lines order analyze protein expression, trafficking, degradation and function. α1 G160 mutations significantly decrease potency arguing a positional effect on neighboring consequently glycine-binding within ligand-binding pocket. Disturbed glycinergic inhibition due T162 an additive biogenesis structural changes site. Protein trafficking ER towards ER-Golgi intermediate compartment, secretory Golgi pathways finally surface largely diminished, but still sufficient deliver channels are functional at least high concentrations. The majority mutant accumulates conducted ER-associated proteasomal degradation. Hence, important determinant during binding. In contrast, assigns primarily whereas exchanges functionality secondary thereof.