Characterization of newly cloned variant of rat glycine receptor α1 subunit

Responses to glycine, a major inhibitory neurotransmitter within the nervous system, are mediated by glycine receptors (GlyRs). Here, we report the cloning and analysis of a novel splicing variant of the GlyRα1 subunit. This variant, named GlyRα1del, has a truncated cytoplasmic region between transmembrane domains (TM)3 and TM4, and compared to other variants, the truncation is contributed by a different acceptor site in exon 9. We transfected GlyRα1 or GlyRα1del into HEK293 cells, and then examined the glycine-activated currents using a whole-cell patch-clamp recording technique. Maximal currents and current-voltage relationships showed no clear difference between GlyRα1del and GlyRα1. Moreover, dose-response curves indicated that the EC50 values for glycine differed significantly between the two GlyRα1 derivatives, although their Hill coefficients were similar. When present with other isoforms, GlyRα1del might alter the response to glycine or to other agonists, as this variant expands the potential heterogeneity among glycine receptors.