An intramembrane aromatic network determines pentameric assembly of Cys-loop receptors.

Cys-loop receptors are pentameric ligand-gated ion channels (pLGICs) that mediate fast synaptic transmission. Here functional pentameric assembly of truncated fragments comprising the ligand-binding N-terminal ectodomains and the first three transmembrane helices, M1-M3, of both the inhibitory glycine receptor (GlyR) alpha1 and the 5HT(3)A receptor subunits was found to be rescued by coexpressing the complementary fourth transmembrane helix, M4. Alanine scanning identified multiple aromatic residues in M1, M3 and M4 as key determinants of GlyR assembly.

Practical guidelines for diagnostic use of in vitro chemosensitivity tests.

To date, a multitude of chemotherapy sensitivity and resistance assays (CSRAs) have been developed to examine the efficiency of diverse cytostatic drugs on a patient's tumour material in vitro, and therefore provide the opportunity of customizing the particular treatment strategy in vivo. In an attempt to assess the impact of the hitherto developed CSRAs on routine clinical practice, in 2004, the American Society of Clinical Oncology (ASCO) performed a comparative analysis of previously published studies (1966 until January 2004) referring to the diverse assays and came to the conclusion that none of these assays was suitable for routine clinical practice. As the CSRAs aim to support the clinician in selecting the most efficient regimen to be applied to the individual patient, they must comply with several technical requirements.

Molecular basis of gephyrin clustering at inhibitory synapses: role of G- and E-domain interactions.

Gephyrin is a bifunctional modular protein that, in neurons, clusters glycine receptors and gamma-aminobutyric acid, type A receptors in the postsynaptic membrane of inhibitory synapses. By x-ray crystallography and cross-linking, the N-terminal G-domain of gephyrin has been shown to form trimers and the C-terminal E-domain dimers, respectively. Gephyrin therefore has been proposed to form a hexagonal submembranous lattice onto which inhibitory receptors are anchored.

Molecular determinants for G protein betagamma modulation of ionotropic glycine receptors.

The ligand-gated ion channel superfamily plays a critical role in neuronal excitability. The functions of glycine receptor (GlyR) and nicotinic acetylcholine receptor are modulated by G protein betagamma subunits. The molecular determinants for this functional modulation, however, are still unknown.

The beta subunit determines the ligand binding properties of synaptic glycine receptors.

Inhibitory glycine receptors (GlyRs) regulate motor coordination and sensory signal processing in spinal cord and other brain regions. GlyRs are pentameric proteins composed of membrane-spanning alpha and beta subunits. Here, site-directed mutagenesis combined with homology modeling based on the crystal structure of the acetylcholine binding protein identified key ligand binding residues of recombinant homooligomeric alpha1 and heterooligomeric alpha1beta GlyRs.