The P2X receptor binding domain: structure, conformational changes and coupling to the ion channel

• Applicant: Professorin Dr. Annette Nicke, since 4/2010
• Subject Area: Clinical Neurology; Neurosurgery and Neuroradiology
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 22935240

P2X receptors (P2XRs) are non-selective cation channels which are activated upon binding of extracellular ATP. They have an unusual trimeric structure which is unique among the ion channel families known so far. P2XRs show no sequence homology to any other known ion channel or ATP-binding protein. Thus, the information about their structure and location of the ATP binding site(s) as well as the structural rearrangements that lead to channel opening are still very limited and mainly derived from mutagenesis studies. In this study, we propose to use detailed single channel analysis and photoaffinity labeling to determine the minimum number of ATP molecules required to open the channel, investigate the cooperativity between their binding and identify protein domains which are involved in agonist binding. Further we plan to identify and analyze structural rearrangements leading to channel opening and subsequent desensitization. Therefore, we will expand the electrophysiological analysis of mutated receptors by the simultaneous use of fluorescence techniques such as time-resolved voltage-clamp fluorometry and fluorescence-resonance measurements after site directed fluorescence labeling or binding of fluorescent ligands.

• DFG Programme: Research Units
• Subproject of: FOR 748: Neuronal and Glial P2 Receptors; Molecular Basis and Functional Significance
• Ehemalige Antragsteller: Professor Dr. Ernst Bamberg, from 1/2009 until 4/2010; Dr. Jürgen Rettinger, until 1/2009