Single Expressed Glycine Receptor Domains Reconstitute Functional Ion Channels without Subunit-Specific Desensitization Behavior [Molecular Bases of Disease]

August 20th, 2014 by Meiselbach, H., Vogel, N., Langlhofer, G., Stangl, S., Schleyer, B., Bahnassawy, L., Sticht, H., Breitinger, H.-G., Becker, C.-M., Villmann, C.

Cys-loop receptors are pentameric arrangements of independent subunits that assemble into functional ion channels. Each subunit shows a domain architecture. Functional ion channels can be reconstituted even from independent, non-functional subunit domains, as previously shown for GlyRα1 receptors. Here, we demonstrate that this reconstitution is not restricted to α1 but can be transferred to other members of the Cys-loop receptor family. A non-functional GlyR subunit, truncated at the intracellular TM3-4 loop by a premature stop codon can be complemented by co-expression of the missing tail portion of the receptor. Compared to α1 subunits, rescue by domain complementation was less efficient when GlyRα3 or the GABAA/C subunit ρ1 were used. If truncation disrupted an alternative splicing cassette within the intracellular TM3-4 loop of α3 subunits, which also regulates receptor desensitization, functional rescue was not possible. When α3 receptors were restored by complementation using domains with and without the spliced insert, no difference in desensitization were found. In contrast, desensitization properties could even be transferred between α1/α3 receptor chimeras harboring or lacking the α3 splice cassette proving that functional rescue depends on the integrity of the alternative splicing cassette in α3. Thus, an intact α3 splicing cassette in the TM3-4 loop environment is indispensable for functional rescue and the quality of receptor restoration can be assessed from desensitization properties.
  • Posted in Journal of Biological Chemistry, Publications
  • Comments Off on Single Expressed Glycine Receptor Domains Reconstitute Functional Ion Channels without Subunit-Specific Desensitization Behavior [Molecular Bases of Disease]