Single expressed glycine receptor domains reconstitute functional ion channels without subunit-specific desensitization behavior.

ABSTRACT: 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, nonfunctional subunit domains, as shown previously for GlyR?1 receptors. Here, we demonstrate that this reconstitution is not restricted to ?1 but can be transferred to other members of the Cys loop receptor family. A nonfunctional 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 with ?1 subunits, rescue by domain complementation was less efficient when GlyR?3 or the GABAA/C subunit ?1 was used. If truncation disrupted an alternative splicing cassette within the intracellular TM3-4 loop of ?3 subunits, which also regulates receptor desensitization, functional rescue was not possible. When ?3 receptors were restored by complementation using domains with and without the spliced insert, no difference in desensitization was found. In contrast, desensitization properties could even be transferred between ?1/?3 receptor chimeras harboring or lacking the ?3 splice cassette proving that functional rescue depends on the integrity of the alternative splicing cassette in ?3. Thus, an intact ?3 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.

SUBMITTER: Meiselbach H 

PROVIDER: S-EPMC4200267 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature