@article{LanglhoferVillmann2016,
  author    = {Langlhofer, Georg and Villmann, Carmen},
  title     = {The Intracellular Loop of the Glycine Receptor: It's not all about the Size},
  series = {Frontiers in Molecular Neuroscience},
  journal   = {Frontiers in Molecular Neuroscience},
  number    = {9},
  doi       = {10.3389/fnmol.2016.00041},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165394},
  pages     = {41},
  year      = {2016},
  abstract  = {The family of Cys-loop receptors (CLRs) shares a high degree of homology and sequence identity. The overall structural elements are highly conserved with a large extracellular domain (ECD) harboring an α-helix and 10 β-sheets. Following the ECD, four transmembrane domains (TMD) are connected by intracellular and extracellular loop structures. Except the TM3-4 loop, their length comprises 7-14 residues. The TM3-4 loop forms the largest part of the intracellular domain (ICD) and exhibits the most variable region between all CLRs. The ICD is defined by the TM3-4 loop together with the TM1-2 loop preceding the ion channel pore. During the last decade, crystallization approaches were successful for some members of the CLR family. To allow crystallization, the intracellular loop was in most structures replaced by a short linker present in prokaryotic CLRs. Therefore, no structural information about the large TM3-4 loop of CLRs including the glycine receptors (GlyRs) is available except for some basic stretches close to TM3 and TM4. The intracellular loop has been intensively studied with regard to functional aspects including desensitization, modulation of channel physiology by pharmacological substances, posttranslational modifications, and motifs important for trafficking. Furthermore, the ICD interacts with scaffold proteins enabling inhibitory synapse formation. This review focuses on attempts to define structural and functional elements within the ICD of GlyRs discussed with the background of protein-protein interactions and functional channel formation in the absence of the TM3-4 loop.},
  language  = {en}
}
@article{AtakLanglhoferSchaeferetal.2015,
  author    = {Atak, Sinem and Langlhofer, Georg and Schaefer, Natascha and Kessler, Denise and Meiselbach, Heike and Delto, Carolyn and Schindelin, Hermann and Villmann, Carmen},
  title     = {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},
  series = {Frontiers in Molecular Neuroscience},
  volume    = {8},
  journal   = {Frontiers in Molecular Neuroscience},
  number    = {79},
  doi       = {10.3389/fnmol.2015.00079},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144818},
  year      = {2015},
  abstract  = {Ligand-binding of Cys-loop receptors is determined by N-terminal extracellular loop structures from the plus as well as from the minus side of two adjacent subunits in the pentameric receptor complex. An aromatic residue in loop B of the glycine receptor (GIyR) undergoes direct interaction with the incoming ligand via a cation-π interaction. Recently, we showed that mutated residues in loop B identified from human patients suffering from hyperekplexia disturb ligand-binding. Here, we exchanged the affected human residues by amino acids found in related members of the Cys-loop receptor family to determine the effects of side chain volume for ion channel properties. GIyR variants were characterized in vitro following transfection into cell lines in order to analyze protein expression, trafficking, degradation and ion channel function. GIyR α1 G160 mutations significantly decrease glycine potency arguing for a positional effect on neighboring aromatic residues and consequently glycine-binding within the ligand-binding pocket. Disturbed glycinergic inhibition due to T162 α1 mutations is an additive effect of affected biogenesis and structural changes within the ligand-binding site. Protein trafficking from the ER toward the ER-Golgi intermediate compartment, the secretory Golgi pathways and finally the cell surface is largely diminished, but still sufficient to deliver ion channels that are functional at least at high glycine concentrations. The majority of T162 mutant protein accumulates in the ER and is delivered to ER-associated proteasomal degradation. Hence, G160 is an important determinant during glycine binding. In contrast, 1162 affects primarily receptor biogenesis whereas exchanges in functionality are secondary effects thereof.},
  language  = {en}
}